Latitude:                             40° 28' 36"N

Longitude:                          80° 01' 58"W

Quadrangle:                       Pittsburgh West 7 1/2'

Age:                                   Pennsylvanian

Formation(s):                        Conemaugh Group, Glenshaw Formation, Woods Run limestone through Lower Saltsburg sandstone.

Purpose:                                   This is the type locality of the Woods Run limestone.

Park near 1318 Woods Run Avenue. Walk to small cliff behind house at that address. Woods Run is exposed about 5 feet above base of outcrop. Parking available for motor coach. Recommended for all age groups.

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

From Oakland, take any bus to downtown Pittsburgh. Then take 16D and get off on McClure avenue near Woods Run Avenue. Walk to site. Return.

From the Cathedral of Learning, Drive 0.7 mi. west on Fifth Avenue. Make a Left on Craft Av. Go 0.1 mi., then make a right onto Blvd. of Allies, go 0.3 mi. then bear right onto entrance ramp to I-376. Go across Duquesne Bridge and follow exit to Rt. 65 (Ohio River Boulevard). Follow Rt. 65 to exit for Rt. 19N. Take exit and follow Rt. 19N for 0.6 miles. Make a left onto Brighton Road. Follow Brighton road for 0.7 miles. Make a left onto Woods Run Avenue. Park as directed above.

See map and figures.

This is the type locality of the seldom exposed Woods Run limestone. The very argillaceous limestone is marine in origin and contains a moderate diversity of fossils. It is immediately overlain by a shale sequence. These shales are in turn cut into and overlain by the Lower Saltsburg sandstone channel.

Geologic History: Environment of Deposition:

The Woods Run limestone is part of a major transgressive sequence extending from the Brush Creek limestone through the Ames limestone, that resulted in a marine inundation of much of what is now western Pennsylvania. The Lower Saltsburg sandstone represents a brief regression as a distributary channel prograded out into the shallow sea. The intervening shales are most likely prodelta clays and delta front sediments that were deposited in front of the advancing channel.

Paleogeographic map of the region during Woods Run limestone time.

Distributary Environment  (from Horne and others, 1978).

Click on the thumbnails below for pictures of the outcrops:

A close-up of the poorly exposed Woods Run limestone.

The section exposed between the Woods Run and the Lower Saltsburg sandstone (at top).

A close-up of the Lower Saltsburg sandstone and the cross-bedding near the uneven erosional base.

A moderately good fossil collecting locality. In general, the quality of the outcrop is poor so samples of float are easiest to locate.

Busch, R. M., and Brezinski, D. K., 1984, Stratigraphic analysis of Carboniferous rocks in southwestern Pennsylvania using a hierarchy of transgressive-regressive units: Field Trip Guidebook for the Eastern Section Meeting of the American Association of Petroleum Geologists. 104 p.

Brezinski, D. K., 1983, Developmental Model for the Appalachian Basin marine Incursion: Northeastern Geology, v. 5, p. 92-99.

Donahue, J., and Rollins, H. B., 1974, Conemaugh (Glenshaw) Marine Events: Field Guidebook for the third Annual Meeting of the American Association of Petroleum Geologists. 104 p.

Donahue, J., and Rollins, H. B., 1979, Coal Geology of the Northern Appalachians: Field Trip Guidebook for the Ninth International Congress of Carboniferous Stratigraphy and Geology. 45 p.

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.

Hoskins, D. M., 1973 third printing, Fossil Collecting in Pennsylvania: Pennsylvania Geological Survey Bulletin G 40, 126 pages.

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.

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)