Bedrock Lithology

The Pike Run watershed lies within the Kanawha section of the Appalachian Plateau province. To the east is a mature upland plateau that constitutes the Allegheny Mountain section of the Appalachian Plateau. The Kanawha section consists in most places of rounded hills and ridges. The interseam crests reach on elevation of 1200 feet and mark a slight undulating surface. The entire drainage area is a tributary of the Mississippi River basin with the Ohio River being the immediate master stream. Pike Run drains to the east into the Monongahela.  The sedimentary rocks which crop out in the area range in age from middle Conemaugh on the north to the  younger Permian beds in the southwest.   The Waynesburg coal bed separates the Pennsylvania system from the transitional Pennsylvania/ Permian systems. The thick Waynesburg "A" coal bed and middle member of the Waynesburg formation, composed of siltstone, local shale, and limestone are overlain by the Waynesburg "B" coal bed.
The Washington coal bed is at the base of the lower Permian and the Washington formation of the Dunkard group. Siltstone and shale overlie this. The layered rock sequence in this area has a general slope to the southwest.
The uppermost headwaters begin just west of the Waynesburg Syncline. The base of the Pittsburgh formation is at about 520 feet at this point. As the main channel proceeds east as it crosses the Belle Vernon Anticline at about ¼ mile upstream of Shaverstown. The Pittsburgh formation is now at 1000 feet. The total map distance form syncline to anticline is approximately 4 miles. This indicates a dip in the bedrock of 130 feet/mile towards the northwest between the axis of the syncline and anticline.
As Pike Run proceeds to the river, the layers now dip to the southeast. The Pittsburgh formation is based at 700feet at the mouth of the stream. The rate of dip between the anticline and the mouth, is a map distance of 2 ¾ mile is110 feet/mile.
The upper portion of the watershed is draining through the upper formations of the lithology. The Greene, Washington, and Waynesburg formations. The lower part of the basin is located in the Waynesburg, Uniontown, and Pittsburgh formations and the uppermost portion of the Conemaugh.

Pittsburgh Waterways Today form the Geologic Past Even though the glaciers never made the trip as far south as Pittsburgh dropping off till filled with carbonate deposits, there is still an effective acid neutralizing capacity in the area. The geologic history of southwestern Pennsylvania involved the creation of calcium carbonate rich limestones and sandstone with some calcium carbonate. These bed-rocks are also excellent providers for vast underground aquifers for the region because the water can move more easily through these rocks' pore spaces. Shales, also found in the area, have less pore space, so water must use fractures and cracks instead.
The geologic history of Pittsburgh during the Pennsylvanian and Permian periods also created and economically important resource--coal. However, mining process of these vast coal-fields and the abandoned mines have a very negative impact on the waterways, creating acid mine drainage, the release of metals, and serious soil erosion. This geologic gift to the area also gives the area its number one source of water pollution. (R. Vargo)