Latitude:                             40° 26' 23"N

Longitude:                         79° 53' 56"W

Quadrangle:                       Pittsburgh East 7 1/2'

Age:                                            Pennsylvanian

Formation(s):                     Conemaugh Group, Casselman Formation, Morgantown sandstone

Purpose:                            This site provides a close-up look at the internal structure of a sandstone channel.

Outcrop is at road level along sidewalk. Parking available for motor coach in Frick Park lot (see site PGHBE 4-1 and seek permission). Alternatively park in church parking lot adjacent to site. Recommended for all age groups.

(Make sure you get an up-to-date PAT Transit schedule:

From Oakland, take a 61A or 61B bus to the corner of Forbes and Braddock avenues. Outcrop is on north side of Forbes Avenue.

From the Cathedral of Learning, Drive east on Forbes Avenue. The outcrop is just before the intersection with Braddock Avenue. Park at a safe location, possibly the Church parking lot, or along Braddock Avenue. Walk to outcrop.

See map and figures.

The Morgantown channel sandstone shows some excellent cross-bedding structures here.

Geologic History: Environment of Deposition:

Here, the Morgantown sandstone is a distributary channel that has cut into pre-existing freshwater limestones and distributary mouth bar deposits. The setting is lower delta plain, in a sequence that is prograding over the Ames marine unit which underlies the sandstone here by less than 50 feet.

Lower Delta Plain Environment (from Horne and others, 1978).

Typical Sections from the lower delta plain, bottom section with crevass splay (from Horne and others, 1978).

Typical Sequence from lower delta plain (from Horne and others, 1978).

Click on the thumbnails below for pictures of the outcrops:

A close-up of the cross-bedded sandstone.

A view of the entire outcrop

A close-up of the micaceous sandstone

No fossil have been found at this site.

Edmunds, W. E., Skema, V. W., Flint, N. K., 1999, Pennsylvanian, in Shultz, C. H., ed, The Geology of Pennsylvania, Pennsylvania Geological Survey Special Publication 1, p. 149-169.

Harper, J. A., 1990, Fossil Collecting in the Pittsburgh Area, Pittsburgh Geological Society Guidebook. 50 pages.

Horne, J. C., Ferm, J. C., Caruccio, F. T., and Baganz, B. P., 1978, Depositional models in coal exploration and mine planning in Appalachian region: American Association of Petroleum Geologists Bulletin, v. 62, p. 2379-2411.

Johnson, M. E., 1928, Geology and Mineral Resources of the Pittsburgh Quadrangle, Pennsylvania: Pennsylvania Geological Survey Bulletin A 27, 236 p.

Leighton, H. 1945, The Geology of Pittsburgh and its Environs: A Popular Account of the General Geological Features of the Region: Carnegie Institute Press, 2nd edition, Pittsburgh, PA , 80p.

Shaw, E. W., and Munn, M. J., 1911, Geologic Atlas of the United States: Burgettstown-Carnegie Folio, United States Geological Survey Folio 177 Field Edition, 123p.

Wagner, W. R., and others, 1970, Geology of the Pittsburgh Area: Pennsylvania Geological Survey General Geology Report G 59, 145p.

Click here for  an image of the County Geologic Map (1880)