With some luck we stumbled onto a shale pit near Martinsburg, West Virginia, but it was raining too hard to check out the rocks plus we did not have permission to access the pit. Not to be filling empty, I put my resources to work and by going through the County Planning Commission in the West Virginia, we tracked down the owner, contacted them and gained permission to check the site out.  And yes, the shale had fossils!  Enough for 40 hearty collectors?  Well, I wasn’t sure but I do know that 80 eyes are better than 2 sets of eyes.  I used the one visit to this shale pit in Berkley County for an opportunity for a young lad from Mercersburg, PA area that wanted to shadow a geologist for several hours.  The student joined me, had the opportunity while driving the Interstate 81 corridor to talk and then show him how a geologist maps a shale pit to gain the understanding of the rock and its fossils.

As a game plan started to develop for the May field trip, I decided to include several stops on the northern part of the Skyline Drive.  How could you go wrong with that, several nice overlooks to the east and west and a look at some of the oldest volcanic rocks on the East Coast.  Even the time for lunch worked right in for a stop at a visitors center on the Skyline Drive.  With my preparation work, I learned on a niffy book “Geologic Guide to the Skyline Drive” written by Robert Badger.  What a great resource this publication provided.  The book is sold by Shenandoah National Park or sold at one of their Visitors Center.  I had several email conversations with Dr. Badger before I could purchase the book on his recommendations for trip stops on the Skyline Drive.

Another story about planning this trip is related to a “now abandoned” roadcut of a colorful rock known as unakite (an igneous rock composed of epidote (green) and orthoclase (pink).  Not only is the rock pretty but is one of the oldest rocks on the East Coast, being dated as 1.1 billion years old (bya).  How could you host a field trip into an area where a 1.1 bya rock occurs and not collect a sample?  I read about the location in a geologic report of the Front Royal area written in the 1960’s.  The authors talked about this unakite rock cut, but upon us visiting the area, we learned that a new road was built later and the “published” roadcut was now in the woods (although the old bridge still existed).  Ok, so we found some unakite and now to find the property owner.  That took another later visit when I was just about ready to give up on that site and thought I would ask some neighbors who owns the property.  I approached a kind gentleman at his mailbox and asked who owned the property down the road on the right.  His response was “That is me.”  I believe my eyes about popped out of my head and I felt like a superpower had guided me here at this exact moment.  I had a nice talk with this German-raised citizen and he had lots of questions about geology.  He allowed us access to the property, lined up parking for our coach bus and even met us there on the day of the trip.  I managed to collect him a fairly large unakite sample which I placed in his vehicle.  He ended our conversation by wanting a group shot of us by the bus, which he took.  I believe we thought we were celebrities in a parade!!

So with all of the planning complete and writing of the guidebook for the trip, my wife and I boarded the coach bus in Hanover, PA, rode to Waynesboro and picked up our participants.  The trip turned out to be wonderful and actually the weather was quite pleasant.  O yes, our fossil site near Martinsburg.  It turned out as I hoped, 80 eyes found more than our 4 did and nearly everyone ended the day with some nice shells, crinoids and bryozoan samples.

Below I included several of the stops that might be on interest.  Stop 1 is located just south of Front Royal along Rte. 522 for the volcanic rock known as metabasalt.  Watch for police here as they sometimes will ask you to move on although the shoulder along the road is quite wide.  Stop 2 is the unakite site; Stop 3 is the first major overlook on the Skyline Drive with an interesting rock cut; Stop 4 is the famous metabasalt columnar jointing roadcut and Stop 5 is a classic limestone cut with fossils south of Strasburg, VA.

STOP 1.  VA ROUTE 522 CATOCTIN METABASALT

Keywords:  metabaslt, metamorphism, chrysotile, epidote, joints, vesicles

Ready to go find some geology?  Our first stop involves a rock that once was lava approximately 540-600 mya during the Proterozoic and Early Cambrian periods.  Some of the earliest research on the dating of this rock had its age up to 820 mya but revisions of the dating techniques, overlying stratigraphy and fossils has refined the dates.  The rock is now called a “meta” basalt since it was affected by heat and pressure (metamorphism) at least one time and probably twice in its history.  The rock is dark-green in color due to its mineral content.  Minerals such as chlorite, actinolite and epidote are present.  Larger pods of epidote can occasionally be seen in this roadcut.  Also veinlets and pockets of whitish chrysotile (fibrous serpentine) is frequently seen,  The rock weathers to a greenish-brown color.  The vertical cracks seen in the bedrock are known as joints, a structure formed as a result of movement after the lava became lava, during a mountain-building episode (known as an orogeny).  You will notice how dense the rock is when struck with a hammer.  Be careful of flying pieces or how close you are to someone when striking the rock.  Often it is better to search out a piece of metabasalt that has already been displaced from the roadcut to crack.  Make sure when collecting a sample, you get a piece exhibiting the dark green fresh color.  You will also encounter in this roadcut some small quartz veins cutting through the metabasalt. Also look for small cavities in the rock.  These are known as vesicles and were formed as gas escaped from the rock leaving a cavity and never filled in with mineralization. The thickness of the Catoctin Formation is 1,500-2,500 feet in this area (Rader and Biggs, 1976).

If the Catoctin Formation metabasalts sound familiar, we have visited this rock closer to home on past fieldtrips.  Since the metabasalts are found only in the Blue Ridge Province, South Mountain in Pennsylvania contains a rock that looks fairly identical to the rocks here in Front Royal.  Locations in Pennsylvania where we have visited this rock include Jacks Mountain tunnel, The PennDot shed on Pa. Rte. 16 near Carroll Valley and at the Specialty Granules quarry in Charmain.

Also, interestingly, its twin brother rock known as rhyolite which is found in the northern part of the Blue Ridge Province is absent in this area.  Matter of fact, rhyolite is seen as far south as near Frederick, Maryland in the Blue Ridge but not any further south.

The metabasalt represents a period of rifting associated with the early opening of the Iapetus Ocean.  Approximately 600 mya ago, a supercontinent known as Rodinia was breaking apart.  The basalt formed as a result of oceanic rifting similar to what is occurring along the Mid-Atlantic Ridge in the Atlantic Ocean.  The rhyolite reflects a period of rifting related to the continental crust being torn apart, but as indicated above, this rock is not seen in this part of the Blue Ridge province.  You will see several classic outcrops of the metabasalt later at Stops 3 and 4.

STOP 2.  VIRGINIA  RTE  649 BASEMENT ROCK EXPOSURE

Keywods: Unakite, orthoclase feldspar, , metasomatism, Rodinia, Middle Proterozoic

            So you want more excitement?  We move to this more remote area at the base of the Blue Ridge Mountains to allow you to collect a rather rare rock, or at least in the Pennsylvania-Maryland  area it is rare.  Known as basement rock, this is the oldest rock known within the Blue Ridge Mountains and one of the oldest rocks known on the East Coast.  The rock varies in composition from location to location, but is generally classified as a granite, grandodiorite, granitic gneiss or in this case for Stop 2 known as unakite.  Along an abandoned road, examples of unakite can be found.  Don’t expect to find much outcrop of the rock as weathering has taken its toll on the unakite.  The best collecting is near or in the small stream at the concrete bridge or in the bank to the east of the bridge.  Also, if you are careful, walk further north on Browntown Road pass the dirt driveway on the right to a small embankment on the right.  There are some pieces of the unakite exposed here.

If you are going to collect along the abandoned roadbed in the woods, take notice to the terrain here.  Look at the hillside as it drops in elevation from right to left.  You can see two distinct drop-offs here.  The higher portion to the right (or in the direction of where the bus is parked) is actually underlain by the Catoctin metabasalt (similar to what you saw at Stop 1).  It is the lower portion of the elevation that contains the unakite (Raqder and Biggs, 1975).  Weathering has taken a toll of the rock and you will have to break some pieces to find a fresh surface.

So what is unakite?   First discovered in the United States in the Unakas mountains of North Carolina from which it gets its name, unakite is an altered granite composed of pink orthoclase feldspar, green epidote, and generally colorless quartz. It exists in various shades of green and pink and is usually mottled in appearance. A good quality unakite is considered a semiprecious stone; it will take a good polish and is often used in jewelry as beads or cabochons and other lapidary work such as eggs, spheres and animal carvings. It is also referred to as epidotized or epidote granite. In some of the Blue Ridge occurrences, an epidotized augen gneiss is present exhibiting foliation structures (http://en.wikipedia.org/wiki/Unakite).

Granite is an intrusive igneous rock.  The rock formed from magma buried deep within the Earth.  The magma never reached the surface, solidifying into a rock probably 4-5 miles deep.  The fact that the crystals in the rock can be seen with your eye tells us that the rock cooled slowly, such as a granite.  You might remember that the metabasalt contains small microscopic crystals indicating that the rock cooled faster compared to the unakite.  Later chemical alteration of plagioclase feldspar by heated water or other solutions created the epidote (metasomatism).

Famous unakite sites exist further south in Augusta and Roanoke counties, Virginia have yielded fine lapidary specimens and can be seen for specimens for sale at area mineral shows or swaps.  A site near Vesuvius can still be collected and yields some fine colorful specimens.

What also makes this rock important to collect is its age.  The unakite is believed to be 1.1 bya and represents an ancient mountain range formed as a result of a continental collision (such as today’s example of the Himalayan Mountain).   This mountain range extended from Texas to Newfoundland.  Some geologists believe the mountain range extended into Mexico (Badger, 2012).  This rock was the crust on a part of Rodinia.  Several larger exposures of the basement are visible along the Skyline Drive between miles 21-33 (Davis and others, 1958; Badger, 2012).

This basement rock is assigned to the Pedlar Formation which is assigned a Middle Proterozoic age on the geologic time scale.  The Pedlar Formation appears to be diminishing out of the more recent works describing the older rocks and only being referred to as the “basement” rock.

STOP 3.  SIGNAL KNOB OVERLOOK – SKYLINE DRIVE MILE 5.3

Keywords:  Massanutten Mountain, Signal Knob, erosion, sandstone, conglomeratic sandstone

            Welcome to the Skyline Drive, a 109-mile long stretch of roadway that runs on the top of the Blue Ridge Mountains from Front Royal to Waynesboro, Virginia.  Along the way, many exposures of sedimentary, igneous and metamorphic rocks are found, which tell the story of the evolution of this famous mountain range, at least in Virginia.  Should you want to learn more about the geology of the Skyline Drive, check out a publication “Geology along the Skyline Drive – A Self-Guided Tour for Motorists” written by Robert Badger (2012).  The book is for sale in the gift shop at the Dickey Ridge Visitor Center (lunch stop).  If you enjoy hiking and are in shape, there is an excellent 7.1-mile round trip hike on Old Rag Mountain north of Syria within the Shenandoah National Park.  “A Hiker’s Guide to the Geology of Old Rag Mountain” written by Paul Hackley (2006) is also available at the gift shop.  Ok, now that the commercial break is over let’s go and see some geology.

As a reminder, while on the Skyline Drive, we need to keep all hammers inside the bus. Collecting of samples are not permitted within Shenandoah National Park.  In a way, that is good as the two exposures we picked out for this trip are good outcrops to look at and photograph but not for rock collecting.  Anyway, you already have a sample of this rock in your possession.

Before crossing the road to examine the exposure, let us take a look at the overlook.  It is hoped while writing this guidebook that Mother Nature is on our side and presents us with a great day to see the landscapes.  Our elevation here is 2,085 feet above sea level (asl).  From here, the next prominent ridge to the west about 8 miles away is Massanutten Mountain, located within the George Washington National Forest.   The mountain bisects the Shenandoah Valley just east of Strasburg in Shenandoah County in the north, to its highest peak east of Harrisonburg in Rockingham County in the south.  The geology of the Massanutten Mountains is dominated by Silurian Massanutten Sandstone, a lateral equivalent of the Tuscarora Formation in the Appalachian Mountains to the west, overlying the Ordovician Martinsburg shale. Erosion of the Martinsburg shale in some areas of the mountain caused the sandstone to break and slide to form talus slopes. The Massanutten Sandstone is folded in a synclinorium, and it outcrops at the ridge tops (http://en.wikipedia.org/wiki/Massanutten_Mountain).

At the north end of Massanutten Mountain is Signal Knob, a location of Confederate lookout and signaling post during the Civil War.

The valley between us and Massanutten Mountain and the large valley west of Massanutten Mountain belong to the Great Valley Section of the Ridge and Valley Province.  This area is underlain with Early Paleozoic-aged limestone, sandstone and shale.  These rocks are softer in composition, allowing weathering and erosion to be accelerated compared to the harder rocks on the ridges.  To the west, further out, is the first ridge of the Appalachian Mountain Section, another member of the Ridge and Valley Province.  From here the ridge is 22 miles in distance.

Let’s cross the road to observe the bedrock!.  Be careful crossing the road and watch for traffic while visiting the site.  This stop is dedicated to our tour participants.  Up to this point you have learned about metabasalt and unakite and some other interesting tidbits of geology.  Here is your time to shine.  Take a look at the exposure and try to theorize what you are seeing.  We love to hear theories, as that is what makes science so interesting.  It is not unusual to have 10 geologists looking at the same outcrop and you get 10 different stories.  We will allow you to investigate and then share your ideas.  There may be prizes involved here.

PLEASE DO NOT READ ANY FURTHER UNTIL OUR DISCUSSION IS HELD.

So here is the dirt on this stop’s rocks.  Um, there is a hint, I used the word “rocks,” meaning more than one rock type.  When you walked over to the exposure and stepped onto rock, you are standing on the top of a metabasaltic flow (Catoctin). Notice at about knee level, there is a different rock appearing.  This rock has a gritty feel to it and looks different when weathered. This is a shaly sandstone and notice as you look upwards through the rock, the rock contains increasingly larger rounded rock fragments.  At the top of the layer, about 15-25 inches thick, there are fragments of quartzite (metamorphosed sandstone).  This is called a conglomeratic sandstone.  In which part of this layer of sedimentary rock was a stronger water current involved?  This part of the exposure tells us that following a period of volcanism, a period where a stream flowed on top of the basaltic lava occurred, probably lasting for several hundred to perhaps several thousand years carrying the sediment.

Above the sedimentary layer, we have another metabasaltic flow (Catoctin).  This layer is several tens of feet thick and would have covered several square miles of area.  Within both volcanic flows look for the cavities in the rock known as vesicles (Badger, 2012).  These were gas pockets that broke leaving a cavity and not yet filled in with any minerals.  You saw a similar structure at Stop 1.

STOP 4.  INDIAN RUN OVERLOOK – SKYLINE DRIVE MILE 10.7

Keywords: Piedmont, columnar jointing

            Moving to our southern-most point on this trip along the Skyline Drive, we visit an overlook that allows you to see to the east.  If weather permits, you can look southeast and east to see out past the Blue Ridge Province which is the Piedmont physiographic province.  Looking east-southeast at a distance of about 23 miles is Warrenton, Virginia.  The Warrenton area is underlain by sedimentary and igneous rocks belonging to the Mesozoic Era.  The valley in front of you is the location of Va. Rte. 522.  The white water tower in the valley to the southeast is at Flnit Hill, a distance of about 5.5 miles.

We are going to walk north from this overlook a short distance and examine the rock on the west side of the road.  We brought you here because this is another (yes, another) exposure of the Catoctin Formation metabasalt.  But there is a special reason to visit this site!!  At this locality you can see the best example of columnar jointing found on the Skyline Drive.  Yes, there are several other nicer examples of columnar jointing in Shenandoah National Park, but they are along hiking trails.

What is columnar jointing?  It is caused by the contraction of cooling magma.  Upon cooling, the surface of a lava flow gradually contracts due to a decrease in volume as the liquid changes to a solid.  As the magma contracts, cracks propagate outward from regularly spaced points; the angles between cracks are also fairly regular.  This process is similar to the formation of mudcracks on a baseball field as water evaporates and the mud dries. The basalt continue to crack, and grow below the surface as the magma cools and crystallizes at depth.  The result is the formation of five-to-six vertical columns that extend from the top to the bottom of the flow.  Most often columnar jointing occurs in thin basaltic flows.  Here the columns are 6-8 inches across, but have been observed within the park as wide as 30 inches (Badger, 2012).

If the lava flow is horizontal, the cracks will be vertical in appearance.  However, if the underlying surface is not flat, then the two cooling surfaces – one on top and the other on the bottom, will not be parallel and the columns may curve.  Columns may also curve due to slight forward movement of the flow during cooling.

A rather famous site, Devil’s Tower National Monument in Wyoming has fabulous columnar jointing.  In Pennsylvania, the only example known by your leader is at the Carbaugh Run Reservoir in Michaux State Forest, southeast of Caledonia State Park.

STOP 5. VA RTE 601 ROADCUT NEAR STRASBURG

Keywords:  Bedding, dip, limestone, micrite, metabentonite, fossils, contact, Taconic Orogeny

            We return back to the valley for our next venture.  After a short drive from Front Royal westward to Strasburg, we will spend the remainder of the day in the Great Valley Section of the Ridge and Valley Province.  The valley is predominantly composed of limestone (a sedimentary rock containing mostly calcium carbonate), dolomite (a sedimentary rock containing mostly magnesium carbonate) with minor amounts of shale and sandstone.  These rocks in this area are Cambrian and Ordovician in age and reflect the building of a continental shelf off of the east coast of an ancient North America known as Laurentia.

This site is a classic site to study carbonate geology.  Within this roadcut which measures about 900 feet long, are layer upon layer of limestone, a small amount of shale and several thin layers of metabentonite.  You will be presented the chance to study the outcrop for a moment and answer these questions:

1. In which direction is the rock dipping into the surface?  Rocks are generally formed on a horizontal or near-horizontal angle.  If the dip is steeper than that, this tells a geologists that some form of tectonic event has occurred to cause this.
2. What is your estimate on the angle of dip?  A vertical dip (90°) would be where the layers go up and down.
3. At what end of the roadcut would the oldest rocks be found?  A law of superposition states that the rocks on the bottom are the oldest, UNLESS  the beds have been turned upside down due to tectonic movement.
4. One last challenge.  There are 3 different formations in this roadcut.  These formations are all mostly limestone and can be generally divided by several small differences within the appearance of the rock.  Below are several characteristics about each formation.  Upon your inspection of the roadcut can you determine where one formation stops and another begins?  From oldest to youngest, the formations are:

New Market Formation: Middle Ordovician in age

Composed of micrite.    Micrite is a limestone constituent formed of calcareous particles ranging in diameter up to 4 μm formed by the recrystallization of lime mud (http://en.wikipedia.org/wiki/Micrite).

The rock is a medium gray, dense rock with medium bedding.

Thickness is about 55 feet with the base exposed in stream bed beneath the bridge.

Fossils present include bryzoan, ostracods, brachiopods and gastropods.

Lincolnshire Formation: Middle Ordovician in age

Thin-bedded dark gray limestone,

Limestone containing black chert,

Light gray cherty limestone and thin (up to 12 inches thick) layers of a buff-colored metabentonite (interpreted as volcanic ash).

Fossils include bryzoan, gastropods, ostracods, trilobite (Homotelus), brachiopods, and algae (Girvanella).

Thickness here is about 590 feet.

Edinburg Formation: Middle Ordovician in age

Cobbly, buff gray limestone,

Slabby to cobbly limestone,

Shaly,cobbly limestone,

Nodular to cobbly limestone,

Dense, black slabby limestone,

Chert,

Irregularly bedded medium-to coarse-grained limestone.

Fossils include cystoid (Echinosphaerites), algae and brachiopods.

Thickness is about 630 feet (Cooper and Cooper, 1946; Edmundson, 1945; Rader and Biggs, 1976).

Your guide will place yellow tape at the contact between the New Market/Lincolnshire formation contact and the Lincolnshire/Edinburg formation contact.

The best fossil collecting in your leader’s opinion is south of a dry wash filled with limestone about two-thirds of the way south.  Several loose rocks with chalky weathering exhibits some darker impressions of fossils.

A little more detail can be told from these rocks.  The New Market and Lincolnshire formations were deposited on a continental shelf during a rather quiet time off of the coast of Laurentia in the Iapetus Ocean.  This continental shelf became well established by the Middle Ordovician Period.   Shortly after the deposition of the Lincolnshire material, a mountain-building event known as the Taconic Orogeny was beginning to occur as a chain of volcanic islands were colliding along the East Coast.  The orogeny is so named as the Taconic Mountains in New England were uplifted during this time.  The Edinburg Formation exhibits some chemistry in the rock that tells us that the ocean was becoming muddy and more fine-to medium sized sediment was being introduced onto the continental shelf.  The overlying Martinsburg Formation, which we don’t see here, formed from sediment that was being deposited within a subduction zone related to the volcanic islands

With some luck we stumbled onto a shale pit near Martinsburg, West Virginia, but it was raining too hard to check out the rocks plus we did not have permission to access the pit. Not to be filling empty, I put my resources to work and by going through the County Planning Commission in the West Virginia, we tracked down the owner, contacted them and gained permission to check the site out.  And yes, the shale had fossils!  Enough for 40 hearty collectors?  Well, I wasn’t sure but I do know that 80 eyes are better than 2 sets of eyes.  I used the one visit to this shale pit in Berkley County for an opportunity for a young lad from Mercersburg, PA area that wanted to shadow a geologist for several hours.  The student joined me, had the opportunity while driving the Interstate 81 corridor to talk and then show him how a geologist maps a shale pit to gain the understanding of the rock and its fossils.

As a game plan started to develop for the May field trip, I decided to include several stops on the northern part of the Skyline Drive.  How could you go wrong with that, several nice overlooks to the east and west and a look at some of the oldest volcanic rocks on the East Coast.  Even the time for lunch worked right in for a stop at a visitors center on the Skyline Drive.  With my preparation work, I learned on a niffy book “Geologic Guide to the Skyline Drive” written by Robert Badger.  What a great resource this publication provided.  The book is sold by Shenandoah National Park or sold at one of their Visitors Center.  I had several email conversations with Dr. Badger before I could purchase the book on his recommendations for trip stops on the Skyline Drive.

Another story about planning this trip is related to a “now abandoned” roadcut of a colorful rock known as unakite (an igneous rock composed of epidote (green) and orthoclase (pink).  Not only is the rock pretty but is one of the oldest rocks on the East Coast, being dated as 1.1 billion years old (bya).  How could you host a field trip into an area where a 1.1 bya rock occurs and not collect a sample?  I read about the location in a geologic report of the Front Royal area written in the 1960’s.  The authors talked about this unakite rock cut, but upon us visiting the area, we learned that a new road was built later and the “published” roadcut was now in the woods (although the old bridge still existed).  Ok, so we found some unakite and now to find the property owner.  That took another later visit when I was just about ready to give up on that site and thought I would ask some neighbors who owns the property.  I approached a kind gentleman at his mailbox and asked who owned the property down the road on the right.  His response was “That is me.”  I believe my eyes about popped out of my head and I felt like a superpower had guided me here at this exact moment.  I had a nice talk with this German-raised citizen and he had lots of questions about geology.  He allowed us access to the property, lined up parking for our coach bus and even met us there on the day of the trip.  I managed to collect him a fairly large unakite sample which I placed in his vehicle.  He ended our conversation by wanting a group shot of us by the bus, which he took.  I believe we thought we were celebrities in a parade!!

So with all of the planning complete and writing of the guidebook for the trip, my wife and I boarded the coach bus in Hanover, PA, rode to Waynesboro and picked up our participants.  The trip turned out to be wonderful and actually the weather was quite pleasant.  O yes, our fossil site near Martinsburg.  It turned out as I hoped, 80 eyes found more than our 4 did and nearly everyone ended the day with some nice shells, crinoids and bryozoan samples.

Below I included several of the stops that might be on interest.  Stop 1 is located just south of Front Royal along Rte. 522 for the volcanic rock known as metabasalt.  Watch for police here as they sometimes will ask you to move on although the shoulder along the road is quite wide.  Stop 2 is the unakite site; Stop 3 is the first major overlook on the Skyline Drive with an interesting rock cut; Stop 4 is the famous metabasalt columnar jointing roadcut and Stop 5 is a classic limestone cut with fossils south of Strasburg, VA.

STOP 1.  VA ROUTE 522 CATOCTIN METABASALT

Keywords:  metabaslt, metamorphism, chrysotile, epidote, joints, vesicles

Ready to go find some geology?  Our first stop involves a rock that once was lava approximately 540-600 mya during the Proterozoic and Early Cambrian periods.  Some of the earliest research on the dating of this rock had its age up to 820 mya but revisions of the dating techniques, overlying stratigraphy and fossils has refined the dates.  The rock is now called a “meta” basalt since it was affected by heat and pressure (metamorphism) at least one time and probably twice in its history.  The rock is dark-green in color due to its mineral content.  Minerals such as chlorite, actinolite and epidote are present.  Larger pods of epidote can occasionally be seen in this roadcut.  Also veinlets and pockets of whitish chrysotile (fibrous serpentine) is frequently seen,  The rock weathers to a greenish-brown color.  The vertical cracks seen in the bedrock are known as joints, a structure formed as a result of movement after the lava became lava, during a mountain-building episode (known as an orogeny).  You will notice how dense the rock is when struck with a hammer.  Be careful of flying pieces or how close you are to someone when striking the rock.  Often it is better to search out a piece of metabasalt that has already been displaced from the roadcut to crack.  Make sure when collecting a sample, you get a piece exhibiting the dark green fresh color.  You will also encounter in this roadcut some small quartz veins cutting through the metabasalt. Also look for small cavities in the rock.  These are known as vesicles and were formed as gas escaped from the rock leaving a cavity and never filled in with mineralization. The thickness of the Catoctin Formation is 1,500-2,500 feet in this area (Rader and Biggs, 1976).

If the Catoctin Formation metabasalts sound familiar, we have visited this rock closer to home on past fieldtrips.  Since the metabasalts are found only in the Blue Ridge Province, South Mountain in Pennsylvania contains a rock that looks fairly identical to the rocks here in Front Royal.  Locations in Pennsylvania where we have visited this rock include Jacks Mountain tunnel, The PennDot shed on Pa. Rte. 16 near Carroll Valley and at the Specialty Granules quarry in Charmain.

Also, interestingly, its twin brother rock known as rhyolite which is found in the northern part of the Blue Ridge Province is absent in this area.  Matter of fact, rhyolite is seen as far south as near Frederick, Maryland in the Blue Ridge but not any further south.

The metabasalt represents a period of rifting associated with the early opening of the Iapetus Ocean.  Approximately 600 mya ago, a supercontinent known as Rodinia was breaking apart.  The basalt formed as a result of oceanic rifting similar to what is occurring along the Mid-Atlantic Ridge in the Atlantic Ocean.  The rhyolite reflects a period of rifting related to the continental crust being torn apart, but as indicated above, this rock is not seen in this part of the Blue Ridge province.  You will see several classic outcrops of the metabasalt later at Stops 3 and 4.

STOP 2.  VIRGINIA  RTE  649 BASEMENT ROCK EXPOSURE

Keywods: Unakite, orthoclase feldspar, , metasomatism, Rodinia, Middle Proterozoic

            So you want more excitement?  We move to this more remote area at the base of the Blue Ridge Mountains to allow you to collect a rather rare rock, or at least in the Pennsylvania-Maryland  area it is rare.  Known as basement rock, this is the oldest rock known within the Blue Ridge Mountains and one of the oldest rocks known on the East Coast.  The rock varies in composition from location to location, but is generally classified as a granite, grandodiorite, granitic gneiss or in this case for Stop 2 known as unakite.  Along an abandoned road, examples of unakite can be found.  Don’t expect to find much outcrop of the rock as weathering has taken its toll on the unakite.  The best collecting is near or in the small stream at the concrete bridge or in the bank to the east of the bridge.  Also, if you are careful, walk further north on Browntown Road pass the dirt driveway on the right to a small embankment on the right.  There are some pieces of the unakite exposed here.

If you are going to collect along the abandoned roadbed in the woods, take notice to the terrain here.  Look at the hillside as it drops in elevation from right to left.  You can see two distinct drop-offs here.  The higher portion to the right (or in the direction of where the bus is parked) is actually underlain by the Catoctin metabasalt (similar to what you saw at Stop 1).  It is the lower portion of the elevation that contains the unakite (Raqder and Biggs, 1975).  Weathering has taken a toll of the rock and you will have to break some pieces to find a fresh surface.

So what is unakite?   First discovered in the United States in the Unakas mountains of North Carolina from which it gets its name, unakite is an altered granite composed of pink orthoclase feldspar, green epidote, and generally colorless quartz. It exists in various shades of green and pink and is usually mottled in appearance. A good quality unakite is considered a semiprecious stone; it will take a good polish and is often used in jewelry as beads or cabochons and other lapidary work such as eggs, spheres and animal carvings. It is also referred to as epidotized or epidote granite. In some of the Blue Ridge occurrences, an epidotized augen gneiss is present exhibiting foliation structures (http://en.wikipedia.org/wiki/Unakite).

Granite is an intrusive igneous rock.  The rock formed from magma buried deep within the Earth.  The magma never reached the surface, solidifying into a rock probably 4-5 miles deep.  The fact that the crystals in the rock can be seen with your eye tells us that the rock cooled slowly, such as a granite.  You might remember that the metabasalt contains small microscopic crystals indicating that the rock cooled faster compared to the unakite.  Later chemical alteration of plagioclase feldspar by heated water or other solutions created the epidote (metasomatism).

Famous unakite sites exist further south in Augusta and Roanoke counties, Virginia have yielded fine lapidary specimens and can be seen for specimens for sale at area mineral shows or swaps.  A site near Vesuvius can still be collected and yields some fine colorful specimens.

What also makes this rock important to collect is its age.  The unakite is believed to be 1.1 bya and represents an ancient mountain range formed as a result of a continental collision (such as today’s example of the Himalayan Mountain).   This mountain range extended from Texas to Newfoundland.  Some geologists believe the mountain range extended into Mexico (Badger, 2012).  This rock was the crust on a part of Rodinia.  Several larger exposures of the basement are visible along the Skyline Drive between miles 21-33 (Davis and others, 1958; Badger, 2012).

This basement rock is assigned to the Pedlar Formation which is assigned a Middle Proterozoic age on the geologic time scale.  The Pedlar Formation appears to be diminishing out of the more recent works describing the older rocks and only being referred to as the “basement” rock.

STOP 3.  SIGNAL KNOB OVERLOOK – SKYLINE DRIVE MILE 5.3

Keywords:  Massanutten Mountain, Signal Knob, erosion, sandstone, conglomeratic sandstone

            Welcome to the Skyline Drive, a 109-mile long stretch of roadway that runs on the top of the Blue Ridge Mountains from Front Royal to Waynesboro, Virginia.  Along the way, many exposures of sedimentary, igneous and metamorphic rocks are found, which tell the story of the evolution of this famous mountain range, at least in Virginia.  Should you want to learn more about the geology of the Skyline Drive, check out a publication “Geology along the Skyline Drive – A Self-Guided Tour for Motorists” written by Robert Badger (2012).  The book is for sale in the gift shop at the Dickey Ridge Visitor Center (lunch stop).  If you enjoy hiking and are in shape, there is an excellent 7.1-mile round trip hike on Old Rag Mountain north of Syria within the Shenandoah National Park.  “A Hiker’s Guide to the Geology of Old Rag Mountain” written by Paul Hackley (2006) is also available at the gift shop.  Ok, now that the commercial break is over let’s go and see some geology.

As a reminder, while on the Skyline Drive, we need to keep all hammers inside the bus. Collecting of samples are not permitted within Shenandoah National Park.  In a way, that is good as the two exposures we picked out for this trip are good outcrops to look at and photograph but not for rock collecting.  Anyway, you already have a sample of this rock in your possession.

Before crossing the road to examine the exposure, let us take a look at the overlook.  It is hoped while writing this guidebook that Mother Nature is on our side and presents us with a great day to see the landscapes.  Our elevation here is 2,085 feet above sea level (asl).  From here, the next prominent ridge to the west about 8 miles away is Massanutten Mountain, located within the George Washington National Forest.   The mountain bisects the Shenandoah Valley just east of Strasburg in Shenandoah County in the north, to its highest peak east of Harrisonburg in Rockingham County in the south.  The geology of the Massanutten Mountains is dominated by Silurian Massanutten Sandstone, a lateral equivalent of the Tuscarora Formation in the Appalachian Mountains to the west, overlying the Ordovician Martinsburg shale. Erosion of the Martinsburg shale in some areas of the mountain caused the sandstone to break and slide to form talus slopes. The Massanutten Sandstone is folded in a synclinorium, and it outcrops at the ridge tops (http://en.wikipedia.org/wiki/Massanutten_Mountain).

At the north end of Massanutten Mountain is Signal Knob, a location of Confederate lookout and signaling post during the Civil War.

The valley between us and Massanutten Mountain and the large valley west of Massanutten Mountain belong to the Great Valley Section of the Ridge and Valley Province.  This area is underlain with Early Paleozoic-aged limestone, sandstone and shale.  These rocks are softer in composition, allowing weathering and erosion to be accelerated compared to the harder rocks on the ridges.  To the west, further out, is the first ridge of the Appalachian Mountain Section, another member of the Ridge and Valley Province.  From here the ridge is 22 miles in distance.

Let’s cross the road to observe the bedrock!.  Be careful crossing the road and watch for traffic while visiting the site.  This stop is dedicated to our tour participants.  Up to this point you have learned about metabasalt and unakite and some other interesting tidbits of geology.  Here is your time to shine.  Take a look at the exposure and try to theorize what you are seeing.  We love to hear theories, as that is what makes science so interesting.  It is not unusual to have 10 geologists looking at the same outcrop and you get 10 different stories.  We will allow you to investigate and then share your ideas.  There may be prizes involved here.

So here is the dirt on this stop’s rocks.  Um, there is a hint, I used the word “rocks,” meaning more than one rock type.  When you walked over to the exposure and stepped onto rock, you are standing on the top of a metabasaltic flow (Catoctin). Notice at about knee level, there is a different rock appearing.  This rock has a gritty feel to it and looks different when weathered. This is a shaly sandstone and notice as you look upwards through the rock, the rock contains increasingly larger rounded rock fragments.  At the top of the layer, about 15-25 inches thick, there are fragments of quartzite (metamorphosed sandstone).  This is called a conglomeratic sandstone.  In which part of this layer of sedimentary rock was a stronger water current involved?  This part of the exposure tells us that following a period of volcanism, a period where a stream flowed on top of the basaltic lava occurred, probably lasting for several hundred to perhaps several thousand years carrying the sediment.

Above the sedimentary layer, we have another metabasaltic flow (Catoctin).  This layer is several tens of feet thick and would have covered several square miles of area.  Within both volcanic flows look for the cavities in the rock known as vesicles (Badger, 2012).  These were gas pockets that broke leaving a cavity and not yet filled in with any minerals.  You saw a similar structure at Stop 1.

STOP 4.  INDIAN RUN OVERLOOK – SKYLINE DRIVE MILE 10.7

Keywords: Piedmont, columnar jointing

            Moving to our southern-most point on this trip along the Skyline Drive, we visit an overlook that allows you to see to the east.  If weather permits, you can look southeast and east to see out past the Blue Ridge Province which is the Piedmont physiographic province.  Looking east-southeast at a distance of about 23 miles is Warrenton, Virginia.  The Warrenton area is underlain by sedimentary and igneous rocks belonging to the Mesozoic Era.  The valley in front of you is the location of Va. Rte. 522.  The white water tower in the valley to the southeast is at Flnit Hill, a distance of about 5.5 miles.

We are going to walk north from this overlook a short distance and examine the rock on the west side of the road.  We brought you here because this is another (yes, another) exposure of the Catoctin Formation metabasalt.  But there is a special reason to visit this site!!  At this locality you can see the best example of columnar jointing found on the Skyline Drive.  Yes, there are several other nicer examples of columnar jointing in Shenandoah National Park, but they are along hiking trails.

What is columnar jointing?  It is caused by the contraction of cooling magma.  Upon cooling, the surface of a lava flow gradually contracts due to a decrease in volume as the liquid changes to a solid.  As the magma contracts, cracks propagate outward from regularly spaced points; the angles between cracks are also fairly regular.  This process is similar to the formation of mudcracks on a baseball field as water evaporates and the mud dries. The basalt continue to crack, and grow below the surface as the magma cools and crystallizes at depth.  The result is the formation of five-to-six vertical columns that extend from the top to the bottom of the flow.  Most often columnar jointing occurs in thin basaltic flows.  Here the columns are 6-8 inches across, but have been observed within the park as wide as 30 inches (Badger, 2012).

If the lava flow is horizontal, the cracks will be vertical in appearance.  However, if the underlying surface is not flat, then the two cooling surfaces – one on top and the other on the bottom, will not be parallel and the columns may curve.  Columns may also curve due to slight forward movement of the flow during cooling.

A rather famous site, Devil’s Tower National Monument in Wyoming has fabulous columnar jointing.  In Pennsylvania, the only example known by your leader is at the Carbaugh Run Reservoir in Michaux State Forest, southeast of Caledonia State Park.

STOP 5. VA RTE 601 ROADCUT NEAR STRASBURG

Keywords:  Bedding, dip, limestone, micrite, metabentonite, fossils, contact, Taconic Orogeny

            We return back to the valley for our next venture.  After a short drive from Front Royal westward to Strasburg, we will spend the remainder of the day in the Great Valley Section of the Ridge and Valley Province.  The valley is predominantly composed of limestone (a sedimentary rock containing mostly calcium carbonate), dolomite (a sedimentary rock containing mostly magnesium carbonate) with minor amounts of shale and sandstone.  These rocks in this area are Cambrian and Ordovician in age and reflect the building of a continental shelf off of the east coast of an ancient North America known as Laurentia.

This site is a classic site to study carbonate geology.  Within this roadcut which measures about 900 feet long, are layer upon layer of limestone, a small amount of shale and several thin layers of metabentonite.  You will be presented the chance to study the outcrop for a moment and answer these questions:

1. In which direction is the rock dipping into the surface?  Rocks are generally formed on a horizontal or near-horizontal angle.  If the dip is steeper than that, this tells a geologists that some form of tectonic event has occurred to cause this.
2. What is your estimate on the angle of dip?  A vertical dip (90°) would be where the layers go up and down.
3. At what end of the roadcut would the oldest rocks be found?  A law of superposition states that the rocks on the bottom are the oldest, UNLESS  the beds have been turned upside down due to tectonic movement.
4. One last challenge.  There are 3 different formations in this roadcut.  These formations are all mostly limestone and can be generally divided by several small differences within the appearance of the rock.  Below are several characteristics about each formation.  Upon your inspection of the roadcut can you determine where one formation stops and another begins?  From oldest to youngest, the formations are:

New Market Formation: Middle Ordovician in age

Composed of micrite.    Micrite is a limestone constituent formed of calcareous particles ranging in diameter up to 4 μm formed by the recrystallization of lime mud (http://en.wikipedia.org/wiki/Micrite).

The rock is a medium gray, dense rock with medium bedding.

Thickness is about 55 feet with the base exposed in stream bed beneath the bridge.

Fossils present include bryzoan, ostracods, brachiopods and gastropods.

Lincolnshire Formation: Middle Ordovician in age

Thin-bedded dark gray limestone,

Limestone containing black chert,

Light gray cherty limestone and thin (up to 12 inches thick) layers of a buff-colored metabentonite (interpreted as volcanic ash).

Fossils include bryzoan, gastropods, ostracods, trilobite (Homotelus), brachiopods, and algae (Girvanella).

Thickness here is about 590 feet.

Edinburg Formation: Middle Ordovician in age

Cobbly, buff gray limestone,

Slabby to cobbly limestone,

Shaly,cobbly limestone,

Nodular to cobbly limestone,

Dense, black slabby limestone,

Chert,

Irregularly bedded medium-to coarse-grained limestone.

Fossils include cystoid (Echinosphaerites), algae and brachiopods.

Thickness is about 630 feet (Cooper and Cooper, 1946; Edmundson, 1945; Rader and Biggs, 1976).

Your guide will place yellow tape at the contact between the New Market/Lincolnshire formation contact and the Lincolnshire/Edinburg formation contact.

The best fossil collecting in your leader’s opinion is south of a dry wash filled with limestone about two-thirds of the way south.  Several loose rocks with chalky weathering exhibits some darker impressions of fossils.

A little more detail can be told from these rocks.  The New Market and Lincolnshire formations were deposited on a continental shelf during a rather quiet time off of the coast of Laurentia in the Iapetus Ocean.  This continental shelf became well established by the Middle Ordovician Period.   Shortly after the deposition of the Lincolnshire material, a mountain-building event known as the Taconic Orogeny was beginning to occur as a chain of volcanic islands were colliding along the East Coast.  The orogeny is so named as the Taconic Mountains in New England were uplifted during this time.  The Edinburg Formation exhibits some chemistry in the rock that tells us that the ocean was becoming muddy and more fine-to medium sized sediment was being introduced onto the continental shelf.  The overlying Martinsburg Formation, which we don’t see here, formed from sediment that was being deposited within a subduction zone related to the volcanic islands

The Moon only has 1.6^th of the gravity as we have on Earth so meteors or asteroids falling toward the Moon are not burned up in the atmosphere as here on Earth.  Although we have not observed any new craters formed on the Moon, impact crater history is well established.  If you take a look at a crater, you will see the crater with a ridge around the outside of the rim.  You may also see a central peak in the middle, caused by a rebound of material splashing up after the impact.  With many craters, you may be able to also observe material thrown outward of the crater known as ejecta.  Not observed unless you were able to visit the area and explore the material in and around the crater would be brecciated (broken and later rehealed) rock and shocked quartz.

Ok, let’s put the above paragraph into perspective to an event that we all have witnessed or created.  How many of us have thrown a rock into a lake or pond?  What a treat to see how far we could throw it or perhaps how many times could we skip the rock across the water.  But, did you observe the reaction with the water as the rock hit the surface.  A “crater” forms in the water at the instant the rock hits the surface; water is   rebounded outward next to the “crater” and a small dimple of water is shot into the air where the rock entered the water.  The size of the rock would influence how high and far the ripple marks went across the water (shock waves).  Perhaps the angle that the rock entered the water influenced some of the above features.  This principle also pertains to impact craters on any planetary body including the Earth.

As geologists began to recognize the present-day features of earthly impact craters, more of these structures began to be identified.  Scientists began to realize that these events left more scars on our landscape more than earlier thought.  Suddenly there were a somewhat lengthy list of confirmed crater and another list that have yet to be confirmed.  Any yes, how those impact crater that are yet to be discovered.  At least on the East Coast, any craters that were formed  more than 350 million years ago may have been altered or destroyed by later continental collisions or riftings.

A list of known and unconfirmed craters in North America is listed at http://en.wikipedia.org/wiki/List_of_impact_craters_in_North_America.  Links to the individual crater with more information can be followed by clicking on the crater name.

I would like to highlight several of the confirmed craters.  Tennessee actually has two craters.  The most famous is lynnCreek Crater located near Gainesboro.  The crater was created about 360 million years ago (mya).  The  crater is a shallow saucer-shaped depression measuring 3.8 km in diameter.  Depth is 150 m with  a large central cone.  The limestone and dolomite laying in the center of the crater have been thrown upward about 300 m.  It is estimated that the body striking the crust here was traveling 11.2 – 72 km/second.  The Geological Society of America has published a report about this crater.

The second impact crater in Tennessee is the Wells Creek Crater.  The crater is 12 km in diameter and formed during the Jurassic Period (200 mya or another surrounding geologic period.  What this crater is known for is the shatter cones found in the rocks within the crater.  The finest examples of these in the world have been identified from here.  These cones as they appear in the rock were created by the shock waves passing through the bedrock, fracturing the rock in a patterned “cone” shape.

Moving to Ohio, the Serpent Mountain Crater is located in Adams, Highlands and Pike counties.  The crater is about 8 km in diameter and the best date it was formed is placed less than 320 mya.  There is a central peak, transition zone and a trough-shaped rim present.  The bedrock has been brecciated and rehealed with minerals due to the impact.

The closest impact crater to us is known as the Chesapeake Bay Crater.  Located in the southern reaches of the Chesapeake Bay in Virginia, this crater was formed 35.5 mya.  The crater is 90 km in diameter and 1.3 km deep.  The crater was discovered in  1983 when ejecta material was observed in well borings off the coast of Atlantic   City.  In 1993, oil exploration in the area of the crater confirmed its presence.  Presently, researchers are drilling into the center to establish if the cosmic body is still present or if it vaporized upon contact.  Certainly if you were in York County 35.5 mya, that would have been the leading  headlines in the newspaper the following day.

Finally, the leading theory to why the dinosaurs became extinct was a asteroid collision.  It is believed that the 170 km diameter Chicxulub Crater in the Yucatan was the main focus of the extinction.

Sometimes, the body striking the Earth is referred to as bolides.  There are several different definitions of bolides in both astronomy and geology.  In astronomy, a bolide is a meteor that breaks into smaller fragments.  In geology, a bolide is a body that strikes the Earth (a meteorite).

Watch out for a future blog on a local cosmic body known as the Shrewsbury Meteorite.

My first topic is probably one of the most popular subjects where readers have responded.  It is on gold in the area and this was one of my first ever blogs I wrote.  I spilled the beans in that blog with locations where gold is best to be found in York and Lancaster counties.  Several weeks ago one recreational prospector named Chris Martz sent me a picture of a gold nugget he found in PetersCreek in LancasterCounty.  PetersCreek in southern portion of the county is regarded by myself as the best gold-producing stream in southeastern Pennsylvania.  Recreational panners from the region descend on that area asking property owners to access the stream.  The nugget was analyzed by a jeweler and weighed in at 22 grams.  Nice find  Chris and it was the first nugget that I have seen come out of this area.  I still recommend to folks wanting to learn the art of panning to join a chapter of the Gold Prospectors Association of America.  By being a member, you have access to a number of claims across the country, proper insurance and around those folks who have knowledge on panning and gold.  Locally, the Delaware Valley Chapter has several claims in southeastern Pennsylvania and meet in the Reading area.  Check their website out for details.

In relation to gold panning, the York County Parks  popular Panning for Gold day in Spring Valley County Parks is coming up on Saturday, July 27^th from 9am – 2 pm.  This is always a fun time for everyone and you can actually find gold in the East Branch of the Codorus Creek should luck be on your side.  The program is free and no registration is requited – just show and go.  Some pans will be available or you can purchase a pan there from the East Coast Gold Panners and Treasures Hunters Association.  Expert gold pannres also come into the park since they know that the last Saturday in July is the only day throughout the year that gold may be removed from the stream (due to Park regulations).

A common question I receive from new folks into this hobby is where can they go panning.  Unfortunately, there is no public land in the state where panning is allowed.  Property owners have to be consulted for permission and I know to new folks that is hard to do, especially if you are from outside the area.  I feel bad for these folks that there isn’t any public lands where they can become educated.  This is the big advantage on joining a gold panning organization.

Another update is the groundwater survey of CarrollTownship in northern YorkCounty.  Jones Geological Services and the United States Geological Survey have teamed to conduct this study as a result of the 2008-2010 earthquake swarm that occurred there.  A theory that perhaps groundwater was involved in these tremors was proposed and we are attempting to look for any hints with that.  The survey is still in  progress with several monitors installed in abandoned wells measuring the water levels.  Results will eventually be posted on my website at jonesgeo.com.  We are grateful to a number of property owners, CarrollTownship and the Dillsburg Area Authority in making this project possible.  I had one report of a small tremor felt west of U.S. Rte. 15 in mid March.  Not large enough to be recorded by any seismographs, a report like this from residents is beneficial in our record keeping.

Speaking of earthquakes, I just saw a short article in the July issue of Earth magazine about very small seismic activity associated with Superstorm Sandy.  Apparently as a result of waves crashing on the bottom of the ocean, into the shore and particularly into each other, this was enough to be detected by seismographs as far west as Seattle, Washington.  The strongest seismic activity was recorded on October 29, 2012.  Much of the seismic activity was recorded by the EarthScope instruments, a temporary array of seismographs that is being set up across the country from west to east.  Not to advertise, but if you would like to read up-to-date information about our Earth and interesting articles subscribe to Earth magazine (www.earthmagazine.org).  Now that is some cool stuff reported about Superstorm Sandy.

My last update is concerning our freshly started tour of the YorkCounty libraries in connection with their Summer Reading Program.  What better  theme for this popular summer activity is Digging into Reading and we have designed a fun child-participation program called “Tracking Dinosaurs.”  I have to admit, I am not a vertebrate paleontologist nor expert on the dinosaurs.  Yes, I know about the dinosaurs and related animals that lived in our area during the early part of the Mesozoic, but when it comes to the more popular dinosaurs like T-rex and Triceratops, the children know more than myself.

We have fun allowing the children demonstrate how dinosaurs walked, trace trackways and make up their own theories about what happened.  The faces you see on some of these children is worth the trip to that library, especially when they find out they are receiving a fossil to take home.  The best reaction of or participants occur after they learned that they have just licked a coprolite to identify it (with the persuasion of myself since I pretend to forget what it is).  Now don’t ruin the experience if you plan to attend one of these library programs, we love to the see the youngster’s reactions.

I admit that science is boring.  Jones Geological Services believes in including some humor into the program to keep the audience attentive.  I think that the humor will help them retain some information or something that may be unlocked later in school when they hear a term that is recalled from such a program as ours.  Every child has their own special expression when they come over to you to say Thank You.

Finally, if you are planning to go on a vacation this summer, drop me an email or through the blog to ask me for some geologic information about your destination.  Remember, geology is everywhere, no matter if it is Disney World, Myrtle Beach, Pennsylvania Grand Canyon, Watkins Glen or Boston. 

Believe me, I spend a couple of hours researching the geology of a destination so I can gain just alittle more out of the experience.  On the other hand, maybe I am half crazy!!

For this blog I have decided to highlight those in YorkTownship.  Although not having many mines (or called banks in the 19^th century), these operations were important and also lead to the naming of a small community in the area.  Five iron mines have been identified in YorkTownship.  The best documentation of these banks comes from Persifor Frazer,  Jr. when he completed a report in 1874 on all of the iron mines in York and Adams counties.  During his survey for the Pennsylvania Geological Survey, Persifor visited each site and reported its status.  The report was published in 1876. All information below in italics is information taken from Frazer.   In his book “History of York County”, published in 1886, Gibson also presented some details regarding the OreValley area mines.

The Moser’s (new) Bank is located in a wooded area east of the intersection of Cape Horn Road and Ruppert Road.  Kreutz Creek is found just to the east of the wooded area.  Although this bank is situated just outside of the township boundaries, it is still noteworthy and several banks existed near this operation within the township.

“It was opened in 1865 and leased by Mr. Myers of Marietta, but has not been worked fro some years.  The clay banks and bottoms are much covered by vegetation.  The engine house is still standing, although the machinery has been all taken away.  The exposure is very poor, but the ore is seen in places in the sides of the pit.  The specimen obtained from this bank was a pale buff limonite, containing the other hydrated oxides of iron and much clay.”

Presently, the visible pit measures about 150 feet in length with much underbrush.  Some tailing piles are found on several sides of the pit.  During the winter months, a foundation of the probable engine house can be seen on the eastern side toward Kreutz Creek.

Ensminger’s Openings were reportedly about 1,700 feet southwest of the Moser’s new bank.  Remnants of this bank are found in a wooden area in Bellview Acres, immediately south of FitzPark.  Several tailings piles and shallow depressions still exist.

“The east bank was opened in 1866 by K. H. Storm and Price.  It was reopened last fall, 1873, by Mr. Powell of York.  It has never been properly worked.  Some of the ore has been sold to Myers and Hess.  It is thought to be a “vein” by Mrs. S. Ensminger, by which is to be understood that the ore is tolerably regular and continuous.”

The Moser’s (old) Bank is located just north of the intersection of Springwood Road and Camp Betty Washington Road in what is known as “OreValley.”  Can you guess where this term came from?  This is obviously the largest iron operation located in YorkTownship and today the best preserved.  The Schaefer family owns the property on which the mine stands.  The bank is now water-filled and used by the family as a recreational spot.  The Schaefer house actually is built on a large tailings pile.

Mr. Schaefer stated that the bank filled up with water very suddenly while the workers were relaxing under a cluster of apple trees.  It was reported that the carts and mules were still in the hole when the flooding occurred.  Mr. Schaefer also remembers hearing that the operation goes as far as the OreValleyElementary School.

“The excavation, which is very great in size, has almost entirely fallen shut, and the sides are obscured by the wash from above, while there is considerable water in the bottom.”

“The bottom is strewed with lumps, of which much is compact and lean. The length of the bank is about 250 yards, and the deepest part being at the northeast end. The amounts of lump and wash ore obtained from this bank were about equal.”

This bank was originally opened about 1824 and worked first by the York Furnace Company; second by John A. Wright & Company; third by Schonberger, Musselman & Company; fourth by Musselman and Watts, and fifth by Musselman & Sons.  The total yield from the time Schonberger, Musselman & Company purchased the bank in 1850 was 42,090 tons.”

“The ore was hauled to York at about $1.00 to $1.25 per ton.  The load weighed 3 to 5 tons.  The hauling was done by john Strine, who owned an interest in the bank.  IT was taken out of the bank both by carts and inclined railroad.  It was used by Musselman in his furnace in Matietta.”

Frazer reported finding a sample containing lepidocrocite and stalactite limonite and turgite.  Another specimen collected had rounded crystals and covered with black glassy turgite.

“A partial analysis furnished by the Messrs. Watts was as follows:

Metallic iron                40%

Silica                           32.7%

Sulphur                        Trace

Phosphorus                  1.1%

Water                          8.1%

Sum                             81.94%

Undetermined             18.1%

Moser’s (oldest) opening was located across Springwood   Road from the previous bank.  Today, only a wooded grove shows evidence of a possible location of a bank.  No evidence of any excavations, structures or tailings were observed.  This opening, as described by the name, was the oldest of these openings.  Frazer suggests that this small pit was part of the Musselman & Company operation.

The final bank is not associated with OreValley and in fact nearly along the western fringe of the township.  Located on the north side of LakeWilliams and owned by the York Water Company, a pit measuring 60 feet by 90 feet and several small tailings are still visible, better in the winter months.  The site is about 0.25 mile east of Water Street.  Frazer reported this operation to be on Leader’s Hill.  Several threaded pins with nuts on top were also spotted in the vicinity.  Several specimens of pyrite within the phyllitic rock were also seen.  Frazer reports this bank as “an old opening with no ore showing.”  No definite time frame could be found for this small operation but one would suspect the 1860-1865 period might be a good window.

Probably the most asked question or misunderstanding is where were glaciers located in Pennsylvania? Well, the ice line was south of Scranton and actually located well within the anthracite coal belt of northeastern Pennsylvania.  In central Pennsylvania the great wall of ice made it as far south as about Shamokin Dam north of Selingsgrove.  Northwestern Pennsylvania was also covered with glacial ice.  That means that there was never any glacial ice covering a section of our region.  Because of their appearance, many folks think the conglomerate exposed on the top of the Hellam Hills, such as RockyRidgeCountyPark in SpringettsburyTownship and Chimney Rock in HellamTownship are great examples.  This is actually one of the oldest sedimentary rocks in the state anf not involved in any Ice Age formation.  I wouldn’t say that our area was never affected by the Ice Age.  When the ice was melting about 10,000 years ago, much water was sent down the Susquehanna River, doing rapid downcutting into the landscape and laying the foundation for our topography in the River Hills.  Should you want to read about a Ice Age sinkhole in YorkCounty, search back into this series and find one written on Bootlegger’s Sinkhole near Emigsville.

Map showing locations of the glaciated areas in Pennsylvania

Another question would be Ski Roundtop.  Many folks in the northern part of the county believe this popular ski resort was a volcano.  I can see where that impression comes from.  From our home, we can see the peak and it looks like a volcano.  Well, was it?   Using present-day evidence of rock exposures there, we do not see any volcanic rocks that point to that evidence.  Yes, there are igneous rocks there known as diabase, but these rocks formed deep within the Earth from magma that never made it to the surface.  Nicknamed “ironstone” this rock is massive and very hard. Diabase is very common in northern YorkCounty located within what we call the Piedmont Gettysburg-Newark Section of Mesozoic Basin.  The same rock is found at Devil’s Den and Little Roundtop on the GettysburgNationalMilitaryPark.  If Ski Roundtop was a volcano, all evidence has been eroded away, which is possible since 4-5 miles of our crust has disappeared since 140 million years ago.

Geologic map of the Ski Roundtop area. Red represents diabase.

What other economic minerals were mined in YorkCounty besides iron?  Another good question and those mostly interested in mining history.  If you are not aware, there were at least 170 different iron operations in YorkCounty between the 1770’s and 1910.  YorkCounty was one of the leading iron ore districts in our state and is often overlooked by historians when they are trying to highlight the important early industries.  Back to the question at hand.  Copper was exactly removed from a shaft in the early 1900’s along Bull Road along the Dover-ConewagoTownship line.  Several friends of mine remembered accessing the shaft in the 1950’s.  Today a depression into a hillside represents the shaft.  No name has been found associated with this small operation.  Another small copper operation was located in ManchesterTownship north of Roundtop.  Known as LeCron’s Prospect, this vertical shaft has fallen in and is located in a heavily overgrown woods.  It was reported in the 1890’s that a tooth of a Triassic-aged reptile was recovered.  Small copper mineralization is occasionally found in the northern YorkCounty area mostly that of malachite.  The famous azurite-malachite hole along Old York Road north of Rossville is such an example.  A small amount of lead in the form of the mineral galena was reported in the 1800’s in Frystown, what is now East Philadelphia Street near Sherman Street.  No mining of the galena has been reported.

The Rossville azurite and malachite hole

There has been a family lore story for many generations regarding gold near Airville.  Supposedly, a father and his two sons were prospecting gold from a nearby stream in the 1820’s.  The one son felt he was not receiving his percentage of profit from the work and murdered his brother and father, spending the rest of his life in prison.  There  has not been a report of gold mining in YorkCounty although about 15% of the streams in the county contain gold.

A pan showing magnetite, a heavy mineral found with gold

Another question is regarding faults.  Are there any faults in the area?  This question is often introduced after a major earthquake somewhere in the world and the faults are discussed.  Yes, faults are actually common in most regions and especially in an area such as ours that contain old rocks and have been through several episodes of continental wrecking and splitting.  The Martic Line that crosses YorkCounty in the southern section is probably the most famous fault.  However, the YorkValley where U.S. Rte. 30 runs probably contains the most faults.  If you have a chance to visit one of the area limestone quarries, you can’t miss faults on the walls.  Now are any of these faults still active?  Based on what we have observed, the answer is no.  Although the area has had several earthquakes, we are not certain that they are a result of the release of energy along one of these faults.

A fault exposed in the York Building Products Westgate quarry.

Finally, did we have any volcanoes in York County?  Well yes and you would know this if you are a faithful follower of the blog.  There are volcanic rocks found in the Hellam Hills (exposed at Accomac), the Pigeon Hills (exposed along Beaver Creek Road), along the York County Heritage Rail Trail between Glen rock and New Freedom and along the shore of the Susquehanna River at Holtwood Dam.  All of these rocks are related and are about 600 million years old and formed as a result of an early supercontinent known as Rodinia rifting apart.  If you are familiar with the mid-oceanic ridge, this is how these rocks were formed.

Metabasalt from southern York County

This was my second year at MessiahCollege.  I only teach this course every spring as the demand for this course isn’t strong enough to teach both semesters.  After my 2012 initial teaching experience, I learned how Messiah worked, the quality of the students going there and a better idea of what works and doesn’t work.  I went into this year with a better idea of what to teach and how to present it.  Most importantly, unlike 2012, I forced the students to purchase a lab book.  Last year,  I copied lab exercises out of other manuals I had which did not always do well.  With a lab manual the labs were more organized and more rewarding to the students.    I do have the freedom to pick and choose the weekly topics that will be covered.  This works well as I found out from last year what topics went over like a lead balloon, as the saying states.  However, the little catch is that my supervisor has asked me to include several weeks of oceanography and meteorology, neither of each I know much about.  So, there I go, learning just like the students and thanks to PowerPoint lectures to guide me.   I don’t pretend to know much about these two subjects and I admit to the class that I am not an expert.  Yes, I like to watch weather and am a daily observer to the sky trying to predict what is coming, but I don’t understand the concepts.

So why do I like to teach all ages about the Earth and space?  I really can’t answer that, but I just like talking to anyone about the fields.  Yes, I know that the Messiah College students are taking the course for a required lab credit, but I hope they retain just a small piece of information about the school year is over.  I even indicated several times in class that some of these themes can be useful in buying a house of property.  How about if you buy undeveloped property and need to drill a well?  Dig out your textbook and lab manual and refresh on some of the basics of groundwater.  Should I be living in an area with metamorphic or sedimentary rocks?  Which rock is better to build on for a durable foundation?

During the semester, the students have three “out-of-the-classroom” experiences.  In late April we spent a hour under the stars.  A good friend of mine, Dick Copper, brought his telescope on campus for viewing Jupiter, the Orion Nebula and a star cluster.  Dick teaches astronomy labs at GettysburgCollege.  Also in late April, we went on a 3 hour field trip throughout northern YorkCounty to visit several roadcuts to show the students some concepts we had talked about in class.  The best way to teach earth science is to spend time outside putting your fingers dirty.  Our last class together we went to a local private-owned cave and ended the semester panning for gold in Stoney Run.  I wish everyone could have seen the caving portion.

I took the group to LisburnCave.  I visited the quarry some time ago and realized just how little I like tight spots.  Much of the cave only  has 2-foot high ceilings and you have to like seeing clay closeup as you navigate through the 150 feet of hallways.  Out of my 16 students only 9 individuals choose to go into the cave.  No problem I could relate to those not wanting to experience true darkness when all of lights were turned off.  Because I had to give all of my flashlights out to those not equipped with lights, I remained just inside the cave opening in case there was a problem.  After 45 minutes, I heard voices as the crew was coming out.  They all came climbing out of the opening with smiles and their  faces and muddy.  They actually worked together as a team conquering what some were fearful of, crawling through water and mud ands squeezing through tight spots.

It is always fun to take families on fieldtrips.  You never know how people will react when they find a fossil.  I still remember when a 12 year old found a worm tube fossil.  The expression on her face was priceless.  You would have thought that she just won $1 million.  That is a quite rewarding feeling to see those reactions.  I have said it before that when you break open a rock and expose a fossil, you are the first person to see that particular specimen.  Now that is cool!!

I worry about the new standards coming out for the secondary school level.  I am uncertain just how much earth and space will be included.  The rapid scientific discovery going on with Mars and the remarkable pictures taken by the Hubble Space Telescope certainly keep astronomy in the headlines.  But what about geology?  Perhaps some people look at geology as a low priority.  Just what can we do on a computer to teach the subject.  That appears to be the theme these days,  No more  field trips looking at rocks, mineral and fossils, but look what a computer can model when working with a theory.  In my book, that doesn’t sound like fun.  Remember, earlier, I said that the best way to teach geology is go out and touch it.  I don’t think you get the same experience when moving your mouse back and forth across the computer screen.  Time will tell where the priorities will be with the new standards.

I teach because I enjoy it.  Even talking to senior citizens is really cool.  If you are senior citizen and looking for some enrichment in education, check out the OLLI program at Penn State York.  What a great program with a wide assortment of classes offered.  If you can’t find anything in their catalog that hits a nerve, you better start reading the catalog from the back to the front.  The fee to belong to OLLI and course registration is only about the same amount as you and a spouse going out to eat at a fancy restaurant.  I teach every fall for several weeks   a geology class of some sort.  This coming fall I will be doing several of my favorite “canned” PowerPoint programs in geology and astronomy.   I will also be teaching an experimental course on  “Geology of Tourist Attractions” in the East.

Specialty Granules quarry

Point of Interest A Native Copper Mines in South Mountain Location: From near Mt. Hope southward to Pa. Rte. 16, mostly associated with Copper Run. Once belonging to the P. H. Glatfelter Company of Spring Grove, PA as one of their tree farms, many of the mines are today situated within the Michaux State Forest. Several mines were known on the property of Specialty Granules as well as near the “Underground Pentagon.” The first copper operation was reportedly opened in 1833 and became one of the country’s leading copper districts in the late 1800’s. The last major mining operations shutdown in the 1920’s. Occasional attempts and rumors to start new mining continued into the 1960’s. The area became known to “rockhounders” after several reports were published by geologists in the early 1900’s. The district was also publicized in the “Mineral Collecting of Pennsylvania” published in 1976 by the Pennsylvania Geological Survey. An assortment of minerals, including native copper, have been found on the mine dumps. It was reported that native copper was found during the construction of the “Underground Pentagon.” Specialty Granules also finds native copper during quarrying. Native copper is common within volcanic rocks. The Keweenawan copper deposits in Michigan is geologically similar to South Mountain. Most of the copper is found within the metabasalt and quartz veins associated with this rock. The green color of the metabasalt is not from the copper, but rather epidote and chlorite. The copper was formed from deep groundwater containing the native element, which leached toward the surface rocks undergoing hydration. Weathering of the surface rock created secondary minerals such as malachite, azurite and cuprite. The quartz veins were formed in similar fashion where silica and copper ions crystallized from hot groundwater caused by metamorphism. The groundwater found it’s way into cracks within the metabasalt, cooled and formed the copper-bearing veins. For a detailed description on the history of this copper district, go to http://www.pennminerals.com/Chronicles2.htm.

Jeri and Roxann at the Reed Hill copper mine near Mt. Hope

Point of Interest B Devil’s Race Course, Fort Richtie Road, Franklin County Location: Parking area is located on the west side of Ritchie Road about 0.75 mile north of the intersection of Md. Rte. 491 (Raven Rock Road). Although there is a similar occurrence with the same name just northwest of Specialty Granules, we are going to drive past this Maryland occurrence. Although time does not permit us to stop, please come back and visit this geologic feature. The Devil’s Race Course is known as a boulder field composed of boulders of the Weverton quartzite. The feature is approximately 0.70 mile long and 80-130 feet wide. The boulder field was formed by intense weathering and erosion during the “Ice Age.” These boulders were once part of large outcrops of the Cambrian-age quartzite (metamorphosed sandstone) which got broken into boulders and brought down the valley. A stream can still be heard running under the boulders.

Stop 2. Panning for Gold East Branch of Antietam Creek (need permission) Washington County Solid Waste and Recycling, Bikle Road in Smithsburg, MD. The art of panning for gold has intrigued humans for many years. Since the discovery of gold near Charlotte, NC in 1803 which led to the first commercial gold mine in the United States to the gold rush at Sutter’s Mill, CA, people always get excited when they hear “gold.” Although the author has never panned for gold in this vicinity, you can still learn the how’s and why’s in this short stop. The East Branch of the Antietam Creek flow off of the west side of South Mountain and actually originates within the Catoctin Formation metabasalt. Gold, like copper, forms within volcanic rocks. However, with my experience as well as other recreational panners, gold within South Mountain in Pennsylvania appears to be almost non-existent. It appears that gold within the Catoctin Formation is not very common. The area of our panning is underlain by the Cambrian Tomstown Formation, composed entirely of limestone. You will be instructed here on how to fill your gold pan with sediment and using the water, have the heavy minerals settle to the bottom of the pan and the other “junk” rock washed out of the pan. Heavy minerals would include magnetite (black sand), garnet and possibly gold. We will supply you with a small container if you would like to take your “heavy” minerals home for a souvenir or closer look. History of Gold in Maryland: The following is taken from “Gold in Maryland written by Karen Kuff (1987) published by the Maryland Geologic Survey. Maps and more information can be obtained at http://www.mgs.md.gov/esic/brochures/gold.html “Although gold was first reported in 1849 on Samuel Ellicott’s farm near Brookville, Montgomery County, no production was recorded. There are numerous versions of the first discovery of gold in the Potomac area. In 1861 during the Civil War, a Private McCleary (or McCarey) of the 71st Pennsylvania Regiment (or “1st California Volunteers”) was stationed outside of Washington, D.C. While encamped in the vicinity of Great Falls, he discovered gold. It is reported that the gold was found while washing skillets in a stream near McCleary’s hilltop camp overlooking the old Anglers Club. By 1867 the first shaft was sunk near the site of the Maryland Mine.” “Gold has been mined, panned or prospected intermittently since that date. Active mining ended prior to World War II in 1940 and the last recorded production from prospecting was 21 ounces found between 1950-51. The accompanying graph shows gold production in Maryland from 1868 to 1940. Prospecting continues even today. There is a surge of gold panning interest every few years, especially following an increase in the price of gold.“ “No great fortunes were made by Maryland gold miners. In 1890, Emmons stated that there was little likelihood of any new ventures that would result in sure riches for the operator.“ “On all of this belt …there is no record of any great mine the product of which can compare with the few enormously productive mines…in the west, and there seems to have been a very large proportion of disastrous failures among the many gold mining enterprises that have been undertaken here. There is some reason to assume that many of these failures have been due to ignorance and bad methods of working…the depth to which the rocks have been rotted and decomposed…has tended to make the surface showing underly rich; and has been an important factor in preventing systematic and successful mining in depth.” “Not all gold was obtained as ore from mine shafts; much was found by prospecting with trenches, or panning in local streams. The area around Great Falls has yielded most of the gold found in Maryland. Individuals hoping to find gold in Maryland are still looking in this area. Gold recovered by panning is mostly very fine grained but can range up to coarse sand size. Rarely, nuggets were found, some weighing as much as 4 ounces.”

Gold on top and magnetite on bottom of pan

Stop 3 George Washington State Park, Alt. Rte. 40 Boonesboro, MD Monument (Milk Bottle) composed of Weverton Quartzite If you have or never visited this first monument constructed in honor of our first President of the United States, it is always worth a visit. Each time you walk the short trail up to the monument you see something different. Closely examine the quartzite that composes the monument and enjoy the scenic view from the top of South Mountain. New landmarks are seen every time. Quartzite is a metamorphic rock, once a sandstone that has undergone heat and pressure associated with crustal collisions. The rock did not change chemically, but only texturally. Quartz is still the dominate mineral in the rock. Quartzite is coarser-grained due to the grains welding themselves together to make a larger quartz grain. The rock is hard (7.0 on the Moh’s Hardness Scale). Walking up the trail, float of quartzite are lying all over the ground. Examining the rock in the monument you can trace some indication of bedding. No fossils are present. Also, use your keen eye to pick up several quartzite blocks that appear to have 2 directions of bedding (layering) in the rock. This is known as cross-bedding which represents two directions of wave action at a beach when the rock was beginning to form as sandstone. The Weverton quartzite was used in many of the area’s historical buildings. Because of its durability and blocky shape, it is considered a long-lasting stone for buildings. Although rather hard to cut, the rock would be pretty polished after being cut. Ever wonder where the rock came from when you view a historic building? Chances are that the rock originated close by and hard by horse and wagon. For example, in the case of the Washington Monument, the rock came from right here. As we exit the park and return to Alt. Rte. 40, check out the church on the left side just before we travel down off of South Mountain. From the overlook, you are able to see at least 38 miles. Sidling Hill located on Interstate 68 west of Hancock appears as a notch in the mountain to the west. This section is known as the Valley and Ridge Providence or also called the Appalachian Mountains. This famous mountain range is composed of sedimentary rocks such as limestone, sandstone and shale ranging in age from Ordovician to Pennsylvanian. The wide valley below us is the Great Valley Section of the Valley and Ridge. The reason it is a valley is because the rock is mostly limestone and dolomite with some shale beds. Limestone and dolomite are rather soft, not holding up to the elements of weathering and erosion well, thus underlying valleys. Check out the framed photographs of the scenery on top of the tower which has landmarks indicated.

View looking west from Washington State Park

Point of Interest C Middletown Gneiss Exposure on MD Rte. 17 east of the Catoctin Creek, south of Middletown, MD With time restraints we are not able to show you this roadcut, but we have supplied enough samples for everyone to take home probably the oldest sample you have collected. This rock is known as gneiss, a metamorphic rock that illustrates to geologists just how intense the heat and pressure can become during a metamorphism event. This rock underlies much of the Middletown Valley, but exposures are rather obscure. The gneiss was originally a piece of a granitic crust making up a part of an ancient supercontinent known as Rodinia. The rock has been dated at about 1 billion years old. The rock was later involved in the pulling apart of Rodinia, the collision of a volcanic island arc to the east and the great African-North American collision to form Pangaea. Only if the rock could talk, what a story it could tell!! Gneiss is the highest grade metamorphic rock known. If the rock would have had more heat and/or pressure added, the material may have returned back into magma. When the rock was undergoing metamorphism, the white-colored minerals grouped themselves in a zone and the dark colored minerals gathered into their own zone, giving the gneiss a banded appearance. This rock is also believed to be the oldest rock found deep within South mountain and Catoctin Mountain in Maryland. Enjoy your gneiss!!

Point of Interest D Limonite (Goethite) from an area iron mine Again, because of time restraints, we will supply you with a sample of limonite, a.k.a. goethite. This ore was removed from a number of 19th century iron mines in this region and used in nearby furnaces to manufacture iron. We will see one of those furnaces at our last stop. Most of the mines were open pit, not requiring deep shafts to extract the ore. Much of the ore was laying loose in the clay which only required it to be washed and not removed from bedrock. Pick and shovel were about the only required tools. Horse and wagon removed the ore to its processing station or transported it to the furnace. Where blasting was required to dig into the bedrock, dynamite was not used commercially until 1890. Black powder was the main way to loosen the rock prior to 1980. Be careful, your hands will get dirty handling the limonite.

Stop 4 “Potomac Marble” exposure on Ballenger Creek Pike near the Substation 1.17 north of Points of Rock Road Rock Type: Breccia (Sedimentary) but known as a Fanglomerate due to its origin Age: Triassic Period With my experience of regional geology in southeastern Pennsylvania and now into Frederick County, Maryland, This is the nicest exposure of this rock that I know of. I read about this exposure in a book on Frederick County and Richard Gottfreid, professor geology at Frederick Community College suggested this stop. I have seen the fanglomerate quarried, sawed and polished from a farm in Lancaster County, Pennsylvania and wow, is it ever a pretty rock? Imagine that, seeing the large limestone angular boulders set in a reddish clay matrix, glued together. Yes, the rock has been used in several locations as an ornamental stone. The most famous is for pillars inside the National Capitol in Washington, D.C. I am sure there are smaller uses for the rock such as coffee table tops, chair molding in a room or around a fireplace. Just how did this rock form? The rock is considered Triassic in age. During this time, the area was located at about the same latitude as Miami, FL. The climate was tropical with abundant rainfall. It was also the time that the supercontinent Pangaea was beginning to split apart into the world as we know it. We are standing in what was a rift valley, similar to today’s example of the Red Sea. Land to our west was trying to go with North America and the crust to the east was going with Africa. The land here was sinking during the rifting and the valley walls were very steep. As streams flowed from the east into the rift valley, the streams had plenty of velocity coming down the valley slope and were able to carry larger rock fragments. Once the stream flowed out onto the valley floor, the stream’s velocity dramatically slowed and was forced to drop all of the boulders of limestone. As boulders were deposited on top of older boulder layers, as viewed from the air, the sediment appeared as a fan shape, thus known as an alluvial fan. In a dictionary, the rock would be classified as a breccia (rock containing angular fragments). Since we know the specific origin of the rock as an alluvial fan, the rock is known as a fanglomerate. Notice how the limestone is slightly more resistant to weathering and erosion than the reddish clay. The boulders are a little higher off of the surface. Let’s see who can find the largest limestone boulder!! It is hard to determine any bedding in the rock since the deposition was massive. The fanglomerate is estimated to be about 200 feet thick and exposures are localized. You will see the rock lying on the surface more often than in actual outcrops. Another factor is that these alluvial fans were not continuous along the end of a rift basin, but were spotty. It was reported by the Fredrick County School District website dealing with a geologic guide of the county that fanglomerate was encountered and dug out when the Pier 1 store along U.S. Route 40 was constructed in the last several years.

A pillar inside the National Capitol building in Washington, DC compsed of fanglomerate

Stop 5 Vulcan Materials Quarry – Buckeystown Pike north of Buckeystown (need permission) Frederick formation – limestone – Cambrian age Grove formation – Limestone – Late Cambrian to Early Ordovican Our second quarry of the day is operated by Vulcan Materials Company. According to their website, here is an introduction to Vulcan Materials: “Vulcan Materials Company is the nation’s largest producer of construction aggregates—primarily crushed stone, sand and gravel—and a major producer of aggregates-based construction materials including asphalt and ready-mixed concrete. Our coast-to-coast footprint and strategic distribution network align with and serve the nation’s growth centers. We are headquartered in Birmingham, Alabama.” “Over 300 Vulcan sites produce construction aggregates, and about 200 facilities produce asphalt and/or concrete, which also consume aggregates. All of these are located in the U.S. except for our large quarry and marine terminal on Mexico’s Yucatán Peninsula. The products from this facility are primarily exported by ship to the U.S. Gulf Coast, where quality stone cannot be mined locally For more information on this company go to www.vulcanmaterials.com.” “What we produce is used in nearly all forms of construction. In particular, large quantities of aggregates are used to build and repair valuable infrastructure such as roads, bridges, waterworks and ports, and to construct buildings both residential and nonresidential, such as manufacturing facilities, office buildings, schools, hospitals and churches.” Here the limestone is used primarily for aggregate purposes, for asphalt roads, concrete roads, road base, lightweight block, rip-rap for slope stabilization, stone driveways, construction, etc. The basics of the operation is laying out blasts or shots, blasting rock, loading rock into haul trucks to take to the plant where the various rocks are crushed, screened, and separted into their appropriate sizes. Of course, knowing the geology and having a good mine plan are also important. At one time the rock was mined for use to make cement, however the chemistry is not quite high enough in calcium carbonate as Essroc like so they don’t get rock for that purpose any longer. Some customers use the rock for out of spec AG lime. Two limestone formations occur in this area. The Frederick formation is found within the quarry while the Grove formation lies to the east. Based on stratigraphy of these formations, each limestone unit can be divided further into members. From west to east, they are: Rocky Springs Station member, Adamstown member and Lime Kiln member, all belonging to the Frederick formation. The Grove formation can be divided into the Ceversville member and the Fountain member (west to east). You will be permitted to collect off of a pile of limestone here. Watch for white, yellow or other colors in veins or crystals. This will be calcite, the primary mineral that composed limestone. It has a hardness of 3 on the Moh’s Hardness Scale, has 3 directions or cleavage and forms rhombohedra or dog-tooth shaped crystals. Calcite will react with vinegar with made into a powder or more readily with muriatic acid.

Aerial geologic map of the Buckeystown quarry

Stop 6 Catoctin (Isabella) Furnace in Cunnigham Falls State Park near Thurmont 18th and 19th century iron furnace The historical marker states: ”Catoctin Furnace: An important iron furnace during the Revolution owned by Governor Thomas Johnson and his brothers. Furnished 100 tons of shells used at Yorktowne.” The Johnson Furnace was a cold-blast operation. It operated from 1776 to 1795, and then was idle until 1803. The furnace operated again between 1803 and 1811 with substantial improvements. Early production consisted of household implements, tools, cast iron stoves, etc. The works were purchased by by John Brien in 1831 and modernized. The furnace operated until it was shut down and dismantled in 1880. The site of the Johnson stack was probably in about the middle of the retaining wall behind the existing (Isabella) stack. Another owner built the Isabella Furnace in 1856. Both the Johnson and Isabella stacks were 33 feet high, but the Isabella was supplied with a steam-powered hot blast mechanism. The Isabella operation was a advanced design for a charcoal furnace. It might have been capable to use anthracite or coke, but neither were available. The Isabella is the remaining stack on display. A third stack, the Deborah, was built in 1873 about 140 feet south of the Isabella. It was a water or steam-powered hot-blast furnace which used coke or coal with a daily capacity of 35 tons of pig iron. It operated until 1903 and was then dismantled. In the late 1800’s, when the complex was at its heyday it consisted of: 80 houses for workers, a saw mill, a grist mill, a company store, farms, an ore railroad and 3 furnace stacks. Production was 9,000 tons of pig-iron annually. A magnetite (iron) mine was located on a hill to the southwest and continued to mine until 1912. Today, we should have time to visit the stack area and walk east to see the remains of the ironmaster’s house. Further walking on the trail will take you past slag heaps a raceway and dam for the waterwheel for the Johnson furnace.

Portal of the Catoctin Furnace

The finding of a fossil is always a cool experience.  You are the first person to ever see that particular specimen and you probably know, each specimen is unique in appearance.   Some of you have probably experienced that feeling while fossil hunting.  Just think now if you find a fossil that has never been described before and you know that your find could be very important.

This is the case of Samuel S. Haldeman.  Samuel was born on the homestead just at Locust Grove, now Bainbridge, Lancaster County in 1812.  His father was a  great business man having interests in furnaces, a grist mill and .    He attended a classic school in Harrisburg and then spent two years at DickinsonCollege, although he did not receive a diploma.

The Haldeman homestead at Locust Grove as it appears today.

After his marriage in 1835 to Mary A. Hough of Bainbridge, he moved to a new residence at the base of Chickies Rock, Marietta. Not only did he design the stately home built by his father, he laid out the grounds with native specimens of trees and shrubs gathered from the surrounding woods, and some foreign varieties, all of which were planted with his own hands.

For a time he managed a saw mill. In 1836 Henry D. Rogers, having been appointed state geologist of New Jersey, sent for Haldeman, who had been his pupil at Dickinson, to assist him. A year later, on the reorganization of the  Pennsylvania Geological Survey, Haldeman was transferred to his own state, and was actively engaged on the survey until 1842, preparing five annual reports, and personally surveying the counties of Dauphin and Lancaster.   In 1840 he began the publication of his monograph on the “Fresh-Water Univalve Mollusca of the United States,” in which he described the Scolithus linearis, a new genus and species of animal fossil, the most ancient organic remains in Pennsylvania. During the year 1842/3, he gave a course of lectures on zoology at the Franklin Institute.

Samuel Haldeman circa 1850

In 1852, Haldeman was appointed professor of the natural sciences in the University of Pennsylvania. In 1855 he went to DelawareCollege, where he filled the same position. While there, he also lectured on geology and chemistry in the state agricultural college of Pennsylvania. In 1869, he returned to the University of Pennsylvania as professor of comparative philology. He remained there until his death, which occurred at Chikckies Rock, Pennsylvania.

Scolithus specimen found in the York area

Haldeman was an earnest advocate of spelling reform. He was a member of many scientific societies, was the founder and president of a Philological Society, and one of the early members of the National Academy of Science.

Samuel loved many aspects of the natural sciences.  He built and lived in a mansion at the north end of Chickies Rock.  He studied the plants living there and discovered Scolithus fossils.  Not certain of its origin, Samuel sent a letter to Charles Darwin in an attempt to identify the specimen.  Although I haven’t seen the correspondence or even sure if a letter still exists, historians have stated “that the fossil is Scolithus, a worm borrow of an ancient animal.”  Samuel continued his communication with Charles, helping Charles write the final pages of the classic “The Origins of Species.”  It was determined that Scolithus was a relatively short lived species of only several million years.  The age was placed on the Precambrian and Paleozoic era boundary, on today’s geologic time scale as 545 million years.  Because of its short life span was a species, any rock containing Scolithus can be dated at 545 million years old.  This is known tov a geologist as an index fossil, used as a dating tool.

Samuel Haldeman in his later years

Samuel died in September, 1880 at his mansion.   He left behind 200 publications covered six disciplines he had studied.  Samuel Stehman Haldeman gave his life to his scholarly pursuits, and his influence, though largely unnoticed, is astounding. Many of the most famous and influential scholars of the past were directly influenced by Haldeman both personally and professionally. Haldeman was able to aid in progressive research on many fronts, both scientific and linguistic. The fact that Haldeman was constantly on the cutting edge of every field he studied suggests that he was a man who challenged convention, a man who truly thought for himself. Samuel Haldeman was not only one of the greatest American scholars, but also one of the greatest American thinkers.

Samuel’s mansion he designed and his father built at the north end of Chickies Rock where he died in 1880.

What brought this blog to mind was that I finally visited the HaldemanMansion in Bainbridge this past Sunday.  I was the speaker at the Annual Meeting of the Haldeman Mansion Preservation Society and had a chance to see some of Sanuel’s specimens in his collection.  I even assisted members with identifying several of the artifacts they had questions about.  This society has done much work on the mansion and are still looking for funding to do more, for example, installing a new roof.   This is a great place to visit during the summer when they have open houses and appreciate some of the history of a great person in our local history.

One of those case recently arose.  I had met a gentleman who is very interested in local minerals and has indeed discovered some “cool” stuff on his expeditions in the YorkCounty.  One of his great pieces is petrified wood from Manchester.  Well preserved and rather large for a specimen, I must have looked like a dog waiting for my supper when you showed me that one!!  Certainly one of the best pieces of local petrified wood I have seen from YorkCounty.  Not to get off track, this person had a friend from the Newville, CumberlandCounty area who has done his own research of that area.  With his research he had some questions about items he recovered from the GreatValley region of central Pennsylvania.   So we made arrangements to meet on a Sunday afternoon since that was the only time I had available in the next few weeks and off we go to the Newville area.

I have done very little research in the GreatValley but had time to do some preliminary reading on maybe I should expect to find out there.  I studied the geologic maps since this person gave me an address to check out including Goggle Earth to get a picture of the lay of the land.  With hammer and camera in hand, we met at the designated location (thanks to the GPS) and he gives me some background of what he is doing and has found.  It turns out that much of his research is not geologically related but archaeologically based and certainly I still felt comfortable in that realm.

Float of limestone laying in the field close to the quartz crystals

During the preliminary discussion, I was told what my goal was for the day.  In the rolling hills of the western GreatValley area, this friend uncovered hundreds of small six-sided shaped quartz crystals almost resembling the famous Herkimer diamonds from upper New York state.  Wow, what I had to decide was if these crystals were really transported in from Herkimer for some sort of trading goods from previous residents of the valley or were rthey native to that area?

Again, I did not have much experience of mineral collecting from this portion of CumberlandCounty but I think I would have heard about these clear quartz crystals.  I should have seen some of these crystals for sale at a local rock and mineral show or even a rock swap, but I never did.  After he took me to an area where you has unearthed many of these crystals, I soon drew a conclusion that these crystals were native, weathering out of the limestone.  Wow, so cool and just walking through the freshly dug excavation, these crystals were abundant.  My guide and his friend even have perfected finding these at night using flaahlights at a low angle to the ground to detect their reflection.  Very creative!!!!

Quartz crystals recovered from the Newville area

I wanted to see more of the  immediate area to look at the available rock exposures and loose rocks in the fields.  Upon walking more of the property, I was shown a cave with a vertical entrance which apparently has been known by local cavers for many years.  I knew I was in sinkhole and cavern area knowing the rock formations for which laid under my feet.  Sure enough, with the topography, I located a solution valley that was created when two of more sinkholes combined to make one large sink and later became inactive, forming a narrow, elongated valley.  Other sinkholes were spotted around the edge of this property where residents brought their old metal and disposed of it in the sink.

Anoither sampling of the quartz crystals

Our last stop was at a small inactive quarry where the limestone was well exposed.  A great outcrop to see the structure of the limestone and maybe some more quartz crystals.  Although we didn’t find any of the clear quartz crystals, we did locate a cavity of white quartz crystals.  No other minerals were detected but seeing these clear quartz crystals native to the limestone and having great fellowship with my guides for the day was certainly worth the trip.

Limestone exposed in the abandoned quarry

After I got home and knowing exactly where I was on the trip, I went to my library again to find out if these fine quartz crystals were every reported by a geologist.  Sure enough, when I went to the classic book “Mineralogy of Pennsylvania” by Samuel Gordon in 1922 and I turned to CumberlandCounty, what did I see?  Not one listing of clear quartz crystals but two in the county.  After locating these locations on the CumberlandCounty map and referring to the geologic maps, both of those locations were in the same limestone formation as I visited earlier.  It is hard to believe that among my rockhounding friends that have explored CumberlandCounty, they never said a word about the quartz.

Milky quartz crystals from the abandoned quarry.