Mineral resources of South Mountain and Frederick Valley, Pennsylvania and Maryland

Stop 1. Specialty Granules Corporation, Charmain Road, Blue Ridge Summit, Blue Ridge Summit, PA Geologic Formation: Catoctin of Precambrian age Rock type(s): Metabasalt (greenish) and metarhyolite (reddish) (volcanic) We are grateful and excited about presenting this stop to you. Thank you goes out to Greg Oliver and Charlie Poulson of Specialty Granules for all of the pre-fieldtrip planning and our tour today. They have volunteered to come to the operation to host our tour and their assistance is greatly appreciated. It is hoped that you will see how valuable quarries are, appreciate how technology is used in producing their finished products and realize how many regulations such an operation as Specialty Granules has to follow from the local to federal levels of government. Below are highlights of this operation: Acreage Owned: Over 700 acres Duration: Have been here for 90 years Crushing and screening: Metabasalt is screened from 1.5” to granules Products Producing: Roofing granules in 16 different colors for mostly GAF, Tamaco and Elk Process: Granules are colored and fired. Also produced are unfired, uncolored granules that do not specs. Amount: 600,000 tons shipped of metabasalt granules Transportation: 80% of products are moved by trucks; 20% by railroad Employees: 140 with an average length of service of 17 years Quarry Depth: Current quarry is permitted to 8 levels (approximately 400 feet) Old quarry was down 7 levels (350 feet) but has been back-filled about 250 feet Conveyors: Have 0.75 miles of conveyors to transport rock to different plants and processes Undersized: Have about 50% of the material (600,000-700,000 tons) which is recycled and reclaimed back into quarry Blasting: Once every 7 – 10 days. Have 2 portable seismographs that are deployed out to closest Residences to monitor ground shaking. Problems: The operation often encounters the metarhyolite which no use for is known as this time. Groundwater: No issues since the bedrock is non-permeable and had no porosity Property Border: A beam surrounds the entire border, plainly marking a “Do Not Enter” area. Wildlife: Actual the property can be viewed as a wildlife refuge. Whitetail deer, turkey, bear, coyote, fox, raccoons and birds love this habitat. Other: Have a pond to settle out sediment before entering back into the watershed. Water re-entering watershed is probably cleaner than stream water. Have a on-site weather station to monitor conditions, i.e. for blasting. Geology: Metabasalt and metarhyolite are both igneous rocks that originated from lava. The word” meta” has been placed in front of each rock name because the rocks have undergone metamorphism through crustal plate collisions. Rhyolite forms from volcanic activity on continental crust and basalt is the major component of oceanic crust. These rocks originated as a result of the breakup of an ancient supercontinent known as Rodinia that split apart starting about 700 million years ago. Later, a collision with a chain of volcanic islands and the coming together of Africa and North America caused heat and pressure, slightly altering the rocks. On the tour, we will try to show an example of folding and faulting in the rock.

Specialty Granules quarry

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

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

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

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

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

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

Portal of the Catoctin Furnace

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Samuel S. Haldeman

Regular readers of this blog will remember my many references to Chickies Rock in Lancaster County.   This 110-foot high quartzitic rock  is located north of Columbia and can easily seen crossing the Susquehanna River.  The rock is arch-shaped being folded up by the giant collision between Africa and North America that occurred during the construction of Pangaea some 350 million years ago.  At Chickies Rock, trained eyes will find ripple marks, cross–bedding and a fossil that actually has made this location a famous site.  It is the finding of this fossil and the story behind Scolithus linerais that composes this blog.

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.

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

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

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 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.

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.

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A trip into adventure

In my business of geological education, I meet a lot of people in different geographic areas.  That is probably one of my most favorite things about doing what I do, you hear various stories related to the area’s geology, see new faces and share your interest with them.  Sometimes, during one of our visits to a town to do a program, we luck out and learn something very interesting about the area, probably something I never heard before and the folks have the evidence to proof what they are talking about.

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

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

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

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

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.

Milky quartz crystals from the abandoned quarry.

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Short guide to the geology of central and northern York County

STOP 1.  Hyde Heritage Rail Trail County Park Exposure

Harpers Formation phyllite and quartzite

Located between Hyde and INdian Rock Dam Rock, Spreing Garden Township

  1. Harpers Formation derived from Harpers Ferry, WV
  2. Southern 33% of YorkCounty is composed of metamorphic rocks
  3. This ridge (Country Club Ridge) is just south of the dividing line between the Piedmont Lowlands Section (PLS) and the Piedmont Uplands Section (PUS).
  4. Walk a portion of the exposure and notice what appears to be layering.  Actually this rock has undergone heat and pressure where bedding has become obscure.
  5. What you believe is layering is known as foliation – a feature only found in metamorphic rocks where platy minerals in the rock align themselves to produce a flat plane.
  6. Notice any folding in the exposure?
  7. We are situated very close to a north-south fault.  Although most of the rocks in the PUS are folded, these rocks have been more tightly folded with the influence of the fault.
  8. Find isolated beds of quartzite.  Quartztite is thicker “bedded” than the phyllite and more resistant to erosion.
  9. There are small quartz veins also found here.
  10. Notice how some of the tree roots anchor themselves into the bedrock and are accelerators in weathering of the rock.

 

 

Folding in the metamorphic rocks at Hyde

Folding in the metamorphic rocks at Hyde

 

STOP 2.  Stoney Brook Diabase Dike

Diabase and Conestoga Formation limestone

Along the Railroad just west of the Pleasant Acres Road, Springettysbury Township

  1. Diabase is an intrusive igneous rock giving the rock a coarse-grained appearance.
  2. All diabase in Pennsylvania is Jurassic in age.
  3. A dike is a narrow intrusion of magma in this case only measuring about 20 feet wide, but is about 35 miles in length
  4. This magma was believed to be about 1100º C. and baked the surrounding rock into a metamorphic rock named as a hornfels.
  5. Larger intrusions have formed mineral resources in southeastern Pennsylvania such as the Cornwall Iron Mines, LebanonCounty and Dillsburg magnetite deposit, York       County.
  6. The magma intruded the Conestoga Formation composed of limestone.
  7. Ripple marks have been found in this thinly-bedded limestone.
  8. What is the direction and angle of dip of the limestone?
  9. The Conestoga Formation is one of several limestone/dolomite units in the YorkValley, all forming on a continental shelf off the coast of ancient North America known as        Laurentia.
  10. This limestone is now considered Cambro-Ordovician in age.
Stoney Brook Dike just west of Pleasant Acres Road

Stoney Brook Dike just west of Pleasant Acres Road

STOP 3.  Accomac Metabasalt

Catoctin Formation

Located along the south side of Accomac Road just west of the intersection with River Road, Hellam Township

  1. Formed as a result of rifting of the supercontinent Rodinia about 620 mya.
  2. Basalt forms on an oceanic crust (i.e. mid-oceanic ridge)
  3. Look for quartz pods (filled-in gas bubbles) sometimes showing a trace of copper
  4. Grass-green mineral is epidote and darker green mineral is chlorite
  5. Notice crystal size – extrusive meaning it cooled quickly and is fine-grained
  6. Fractures in the rock are known as joints (fractures where no movement has taken place)  Geologists can take measurements of joints and calculate direction of pressures
  7. Notice one area where bedrock is missing with a small drainage ditch – a possible fault?
  8. Across the road notice the erosion taking place as the stream crosses over the bedrock
  9. The rock has gone at least one period of heat and pressure – metamorphism (meta)
  10. Potholes are well developed in the metabasalt

 

 

Accomac road cut exposing the Catoctin metabasalt

Accomac road cut exposing the Catoctin metabasalt

 

STOP 4. Rocky RidgeCountyPark

Chickies Formation – Hellam Member

Located at the end of Deininger Road, Spring Gettysbury Township.  Proceed to the Oak Timbers North Overlook

  1. Rock containing rounded pebbles is known as a conglomerate
  2. Rock fragments of mostly quartz with occasionally darker fragment of metarhyolite
  3. Can you detect any bedding?
  4. Notice how the fragments are more resistant to erosion – standing higher than rock
  5. Any theories on how this rock formed (include a continental shelf, IapetusOcean and other bodies of water in your thinking)
  6. York, Lancaster, Lebanon and Berks counties can be seen from the overlook
  7. Can you recognize any familiar landmarks?
  8. Harder rocks underlie ridges and softer rocks underlie the valleys, i.e. sandstone and quartzite ridges; limestone and shales in the valleys)
  9. We are at an elevation of about 940 feet above sea level
  10. We can see a distance of 52 miles to the northeast on a clear day

 

 

Hellam Conglomerate exposed at Rocky Ridge County Park.

Hellam Conglomerate exposed at Rocky Ridge County Park.

 

STOP 5. Sheep Bridge Road

Gettysburg Formation shale and sandstone

Located on the west side of Sheep Rock Road just north of the Conowego Creek, Newberry Township

  1. Sandstone has thick bedding and shale has thin bedding. Grain size also varies.
  2. Which of the two rocks is more resistant to erosion?
  3. These rocks were laid down in an “Everglades” environment as Pangaea was rifting apart
  4. Fossils in the area include petrified wood, ferns, dinosaur footprints and reptilian remains
  5. The thickness of the New Oxford and Gettysburg formations are at least 25,000 feet thick
  6. Can you detect the angle of dip and direction?
  7. These rocks are undeformed and positioned nearly the same as when they were deposited
  8. The red color of the rock was created when the sediment was above water level and exposed to the atmosphere
  9. Clam shrimp found in this formation in DauphinCounty indicates fresh water environment
  10. Which layer in this road cut is the oldest?

 

Sheep Bridge road cut exposing Triassic sedimentary rocks

Sheep Bridge road cut exposing Triassic sedimentary rocks

STOP 6. Pinchot State Park Toboggan Run Area

Diabase Exposure

Warrington Township

  1. This is one of the best exposures of diabase in YorkCounty
  2. Compare this diabase with that seen at Stoney Brook
  3. This diabase formed in a sill (a lenticular body of magma) formed at least one mile beneath the surface
  4. In a sill, the magma closest to the outside will cool quicker than the middle
  5. This event was the last stage of the rifting of Pangaea
  6. Igneous rocks weather in a characteristic rounded shape boulders (spheroidal weathering)
  7. Notice the cracks on the rocks – these are believed to be cooling cracks as the magma cooled now magnified by weathering
  8. One could have fun here recreating how the boulders were all connected at one time
  9. The rock develops a reddish-brown weathering rind
  10. How do you think this rock would be for having a good groundwater supply?

 

 

Diabase exposed at Toboggan Run at Pinchot State Park

Diabase exposed at Toboggan Run at Pinchot State Park

 

STOP 7.  Rossville   Road Cut

Diabase and Gettysburg Formation hornfels

Located on the east side of Old York Road, 0.50 and 0.75 miles north of Rossville, Warrington Township

  1. Check the diabase at the lower road cut for grain size – positioned in the middle or on the edge of the sill?
  2. White veins in the diabase of composed of a mineral group known as zeolites.  Heulandite and stilbite are present here in crystals
  3. In the upper road cut, this rock was originally rocks similar to what we saw at Sheep Rock Road but these have been heated by the magma now known as hornfels
  4. Can you detect the direction of the bedding?
  5. A chemical reaction here formed a small amount of native copper to form in the rock
  6. Upon weathering of the rock, native copper will adjust to the new conditions forming azurite (blue and malachite (green)
  7. This rock has no economic value and only occurs on the joint surfaces
  8. Other minerals formed in this method include garnets and opal
  9. Gold is found in area streams, mostly washing out of the diabase
  10. Collect your pieces of samples for the coffee table!
Azurite and malachite exposed in the upper road cut along Old York Road

Azurite and malachite exposed in the upper road cut along Old York Road

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On the road again

March is usually a busy month for my wife and myself.  With Lou Ann as a minister, Lent occurs in March with Wednesday services and other Holy Week activities.  The Geological Society of America Northeastern Section holds their annual gathering also in March.  Not that Lou Ann travels with me, but I was hoping she would have made the trip north to where this blog is being written.  What would you answer if I would ask where is the highest elevation in New England and is the second highest point east of the Mississippi River?  The peak is in the Presidential Range of the White Mountains in New Hampshire and also has a cog railroad that many of you traveled up on a vacation.  The answer is Mount Washington.

No, I am not really on top of the mountain (but I would love to spend a night up there), but the conference is being held at the Mountain Washington Omni Hotel in Bretton Woods.  When they said the resort is at the base of Mount Washington, they weren’t lying.  What a view from the back porch of the hotel!!  Yes, although there wasn’t much snow laying on the ground when we arrived, it is snowing now with several inches expected.  Attending these annual meetings is educational as presenters provide updates on research, talking about the science theories of years past and new technologies.  You get to also see fellow geologists that you only see at these gatherings.

What made me think about writing a blog like this one?  Actually when a fellow geologist friend and myself left the area to head north, I asked him, “If we were to travel in the old days by horse and buggy, I would how long it would have taken to go 545 miles to Bretton Woods?  Yes, alittle exaggerated, but just think about traveling in those days.  One of the papers I heard from a Pennsylvania geologist here was about the first geologic investigation of the Keystone state.  The geologist started in Philadelphia, traveled to Harrisburg, then to Philipsburg and ending in Erie.  Imagine, not only taking a horse and buggy that distance but locating rock exposures, drawing the exposures and staying overnight.  Wow, quite impressive and I don’t think that is for me.

By attending such a meeting as this, you have a chance to compare the field practices of those early explorers to what we use today.  In the early days, they didn’t have topographical maps.  They may have had very crude map showing the mountains, but not much else.  Today we have the use of GPS, 3-D relief maps, highways with a 65 mph speed limit including nice rock exposures and cars.  These pioneering geologists did not have the regional view to correlate rocks, did not really know where the rich coal deposits were nor the important mineral resources or Marcellus gas.

From the 38 themed sessions scheduled at the conference, a lot of information is made available.  Each session lasts up to 3 hours and has presenters every 15 minutes.  Yes, this is what I said!  You have 15 minutes to deliver your information, maybe answer a question.  This meeting occurring in New Hampshire means that many of the papers are centered on New England geology, but you may be able to take some information  back home to use in Pennsylvania.  Finally, the Geological Society is celebrating its 125 years so the conference is running with that theme.  The good news about this annual meeting is that the 2014 meeting will be held in Lancaster, so maybe I will take a horse there to make it feel like old times.

Before I came to New Hampshire, I had several programs to present.  The first program was on the world-famous Peach Bottom Slate for the Harrisburg Area Geological Society.  About 45 geologists attended the program.  You know how they say presenting a program in front of your peers is always the hardest to do.  I find that true also, since everyone has a common interest.  However, you realize shortly into the program that you are in control and let the script roll.  Have fun with the audience as I do.  I judge my audience on how much they laugh at my jokes because science is truly boring unless you spice it up.  The program went well, but during the question period afterwards, I got intimidated.  There was a retired state geologic survey employee in the audience who I knew, but never really talked to him.  He said he had a question and a statement.  I got myself propped thinking that he was going to question something I said.  His question was one about the Susquehanna River which I did not really have a answer for, but told him that.  His statement was that I need a great job presenting the program, so I was relieved.

My other program was a PointPoint program on the Susquehanna River for “Date Night” at Shank’s Mare Outfitters in Long Level.  I have done other programs for this special night over the years and Liz Winand always attracts an interesting group of people for across the region.  This night wasn’t any exception.  There were couples from Lancaster and YorkCounty, some having an interest in geology and others just enjoying the night along the river.  A great group as always with good questions and yes, they laughed at my jokes.

Finally, let me know if there are any topics you would like for me to write about.  I usually write a blog as an educational piece, giving either historic or geologic information for the readers to enjoy.  I have received comments back on numerous blogs with stories of your own or complimentary comments about the blog.  Thank you for those, but do not hesitate to let me know what you would like to see on this page.

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