A Photographic Record of the Ordovician Carbonate Stratigraphic Column from Germany Valley, West Virginia

By Devin Kouts


Trenton Group: Dolly Ridge Limestone


Trenton Group: Nealmont Limestone


McGraw Limestone

30 feet of medium to dark grey granular bioclastic to pelletic limestone. Medium to thick bedded, clay-free, more resistant to weathering, has granular appearance. Forms resistant ledges, "provides an excellent marker for geologic mapping". The top of this unit is highly fossiliferous .*

When Fractured

These images of the McGraw demonstrate the highly fossiliferous nature of the rock. Note the density of fossil remains, far greater than any other unit observed in the valley to date.

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McGraw-McGlone Limestone The top of the McGraw is densely fossiliferous, and weathers to a medium shade of grey. (incandescent lighting) Benbolt Limestone (incandescent lighting) Benbolt Limestone (electronic flash lighting)

McGraw-McGlone Limestone The McGraw fractures very irregularly in comparison to the smooth surfaces on fractured samples of New Market. (incandescent lighting) Benbolt Limestone When fractured the McGraw shows very few crystalline faces, but the edges of fossils are occassionally evident. (electronic flash lighting)

In Situ

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McGlone Limestone

60 feet of interbedded pale to medium grey aphanitic limestone, and darker grey pelmicrite and bioclastic limestone. Forms resistant ledges. The top of the unit is highly fossiliferous.

When Fractured

Conchoidal fracturing, aphanitic appearance. Darker grey than the dove-grey New Market and locally refered to as the "false New Market". Fractured samples often exhibits red streaks or stains.

In Situ

Readily evident throughout Fieldhouse cave.


Big Valley Formation: Benbolt Member

120 feet thick in Germany Valley. Is a medium to dark grey somewhat argillaceous , silty limestone, fossiliferous in parts.*

When Fractured

The Benbolt when fractured is a medium grey color and it displays medium sized crystalline faces (in between those of the Ward Cove and the Lincolnshire). Fractured samples often have a granular appearance, in contrast to the fine grained Ward Cove, but less so than the Lincolnshire.

   

In Situ

Where it is exposed on the surface the Benbolt displays highly conspicuous beds that alternate in constituion. This frequently produces conspicuous overhangs that are often found in the major ravines of Germany Valley. The floors of these ravines are often defined by the contact between the Benbolt and the much darker Ward Cove.

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Benbolt Limestone Thick beds of alternating constitution, typical of the Benbolt, are obvious at the top of the 50 foot drop in Memorial Day Cave. Benbolt - Ward Cove contact At the bottom of the 50 foot pit in Memorial Day cave the contact between the thicker beds of the Benbolt (upper) and the thinner beds of the Ward Cove (lower) are readily visible about 7 feet above the floor.


Big Valley Formation: Ward Cove Member

80 feet thick in Germany Valley, dark grey to black, silty, argillaceous , pyritic limestone. The lower part is an argillaceous knobby limestone with interbedded dark shale.*

When Fractured

These images demonstrate the very fine grained nature of the Ward Cove. It's appearance is much less crystalline than that of the Benbolt, and it is a significantly darker grey, almost black in comparison. The number of crystalline faces range from few in quantity to none.

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Ward Cove Limestone This sample of Ward Cove contains the most crystalline faces observed by this study to date. Coloring is consistently dark and appearance remains fine grained. (Kimble Ravine)    

In Situ

Where it is exposed on the surface the Lincolnshire can weather out in dark, resistant ledges.

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Ward Cove Exposure This image illustrates the tendency of the Ward Cove to weather out in large resistant ledges. Note the large flat faces which break down into fist-sized or smaller gravel as they weather. This illustrates the "knobby" characteristic attributed to the bottom of the unit. Ward Cove Exposure Ward Cove exposed in a Germany Valley ravine maintains its dark appearance. Lincolnshire Exposure In the floors of many Germany Valley ravines the Ward Cove resembles a very solid, nearly black and thinly bedded pavement. Note the ward Cove where it extends out from beneath the asphalt in this photograph. Also note the knobby vertical exposures of Ward Cove behind the house.
Ward Cove Fault This highly conspicuous thrust fault in the Ward Cove is expressed in the walls of a ravine just down stream of the back entrance of Seneca Caverns.


Lincolnshire

Predominantly dark grey, somewhat argillaceous pelletal limestone, with scattered black chert nodules. About 30 feet thick in Germany Valley. The Lincolnshire grades upward into the argillaceous , knobby limestone and interbedded dark shale of the lower Big Valley Formation (Ward Cove Member).*

When Fractured

Especially in the layers immediarely above its contact with the New Market limestone the Lincolnshire is very crystalline with faces that are quite large, larger even than those of the Benbolt member of the Big Valley. The stone at this layer varies in appearance from dark to light grey and when fractured often releases small quantites of crystalline flakes.

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Lincolnshire Limestone This dark sample of Lincolnshire, the size of a 50 cent piece, shows the pelletic makeup of the unit. Lincolnshire Limestone This sample of Lincolnshire is typical of the unit, very crystalline. (Kimble Ravine) Lincolnshire Limestone Another very crystalline specimen of the Lincolshire. Note however the darker color along the upper left edge, versus the lighter color along the lower right edge. (Lower Ruddle Cave)

In Situ

The contact between the Lincolnshire and the underlying New Market is evident as a highly visible disconformity in the entrance area of Convention 2000 cave.

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Lincolnshire Exposure Contact between the Lincolnshire and New Market limestones in Convention 2000 cave. Lincolnshire Exposure In this image from Wild Cat Hollow the hammer is positioned across the contact between the Lincolnshire and the under lying New Market limestone. Lincolnshire Exposure This closeup of the Lincolnshire-New Market contact illustrates the highly crystalline nature of the Lincolnshire immediately above the contact with the aphanitic dove-grey New Market below.
Lincolnshire Exposure Dark chert nodules are most readily seen in the Lincolnshire where it is exposed in the bottom of Germany Valley's many ravines. Lincolnshire Exposure The black chert nodules in the Lincolnshire appear well above the highly crystalline layer at the base of the unit.


St. Paul Group: New Market Limestone

A very pure aphanitic limestone, and the purest limestone in the study area. Is usually mined where it is found, and is a pale to medium grey aphanitic limestone (dove-grey vaughnite), normally massive to thick-bedded. Sparsely fossiliferous. Maclurites and orthoconic. There are cephalopods in the upper part. Cave development can be spectacular, and the end result is often large passages and rooms. Monroe County's Patton and Chambers caves and the lower portion of Pendleton County's Hellhole are formed in the New Market.*

When Fractured

The New Market samples pictured below are the very definition of aphinitic. It is a dense, homogeneous rock and it's constituents are so fine as to be unseen by the naked eye. Occasional crystalline inclusions do appear, however. The New Market fractures very cleanly, and demonstrates qualities similar to limestones that have been metamorphosed into a marble-like nature.

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NewMarket Limestone This sample of New Market Limestone shows small crystalline inclusions. Not uncommon in the New Market, but purer example are devoid of such inclusions. (Shovel Eater -20) NewMarket Limestone This sample of New Market shows the typically dove grey color of the unit.(Convention 2000 Cave) NewMarket Limestone When fractured the New Market breaks very cleanly, and on occasion shows fractures that begin to resemble concoidal fractures in appearance (note fracturing on left side of sample. (Lower Ruddle Cave)

In Situ

NewMarket Limestone This exposure of New Market limestone illustrates the tendency of the unit to erode with deep vertical fissures. The bedding planes here are horizontal despite the appearance that they've been turned on end. NewMarket Limestone Where it appears on the surface the New Market erodes to expose bedding planes from 6 inches to 4 feet thick.


St. Paul Group: Row Park Limestone

A grey limestone with chert nodules and dolomite; fossilerous; thins to the east and southwest; is at the most 100 feet thick.*


Beekmantown Group

Mainly thick-bedded limestones and dolomites; some units contain much chert; is often broken into sub-units; can be as thick as 2500 feet; can be devided into three members in Berkeley and Jefferson counties, is undivided in Mercer and Monroe counties. Mercer county's Beacon Cave and Monroe county's Fletcher cave are both developed in the Beekmantown. Members include Pinesburg Station, Rockdate Run Formation, and Stonehenge Limestone.*


Glossary of terms:

aphanitic - from aphanite, a dense, homogeneous rock with constituents so fine that they cannot be seen by the naked eye.

argillaceous - containing, made of, or resembling clay; clayey .

bioclastic - from bio, referring to living organisms and clastic, referring to a composition of seperable parts or fragments. In this case a rock composed of the fragments of formerly living organisms.

conchoidal fracture - a breakage of rock in concentric circles or in a clam shell-like scar pattern. Referring to the characteristic fractures resulting from pressure and percussion flaking of flint and chert.

fossiliferous - containing or composed of fossils.

maclurite - a class of Ordovician gatropods, of which Maclurite Magnus is a type

pelletic - of or like a small, solid or densely packed ball. In this sense a rock composed of many small pellet like objects. .

pyritic - of or pertaining to pyrites; consisting of, or resembling, pyrites.


*Source: WVASS Bulletin #15, the Caves and Karst of Pendleton County - George R. Dasher

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