Stay to the right. The outcrop is on the left hand side as you drive towards the City of Pittsburgh's Maintenance and storage area. The outcrop continues along the trail to the lake. The Morgantown Sandstone is at the top, with the Birmingham Shale underneath. Geologists use marker beds to help identify which sedimentary layers they are looking at.
Marker beds are strata that are very distictive and stand out.
An important marker bed in the Pittsburgh area is the Ames Limestone. The Ames Limestone has more fossils in it than any otherlayer in the Pittsburgh area. Fossils of Echinoderms , Brachiopods , and Gastropods are found throughout the Ames. The Ames is the boundary between the Glenshaw and Casselman Formations, both part of the Conemaugh Group. The sedimentary rock layers that are exposed directly below the Ames limestone layer in the Pittsburgh area have been deposited mostly as bay-filling muds and other low energy type depositions related to the seaward part of the delta.