Latitude:                         40° 30' 07"N

Longitude:                  79° 56' 37"W

Quadrangle:                    Glenshaw 7 1/2'

Age:                                Pennsylvanian

Formation(s):                  Conemaugh Group, Glenshaw Fm.,  Pine Creek Limestone and underlying Buffalo sandstone.

Purpose:                          This is the type locality of the marine Pine Creek limestone.  A very good fossil collecting locality. Good example of channel sandstone.

Park on the street that goes east off of Rt. 8, just before the locality. Parking is available for only several cars. No motor coach.  Walk down hill to talus slope along Rt. 8. NOT recommended for children. Traffic is very fast and dangerous in this area.

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

From Oakland, take any bus to downtown Pittsburgh. Then 1B, 1C, 1D, or 3D to Etna. Get off in Etna and walk to outcrop along Butler Street (Rt. 8). 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 1.6 mi. then bear right onto I-579. Stay on I-579 across the Allegheny River then get onto Rt. 28 East. Go approximately 6.6 miles and take the exit for Rt. 8 North (Etna). From the end of the exit ramp, stay on Rt. 8 (Butler Street) for approximatly 800 feet. Outcrop is on right. As above, park on side street just before outcrop and walk to outcrop.

See map and figures.

This is a very good outcrop of the Pine Creek marine limestone. Above the limestone are the non-marine Saltsburg shales and siltstones. The shales are dark gray and include compact nodules and sand lenses. small-scale cross bedding occurs in some of the lenses. Below the limestone are fossiliferous marine shales and siltstones that are eventually covered by the talus slope. The Pine Creek crops out as a distinctive 0.5-0.8 m thick limestone bench which consists of a gray to green-gray skeletal mudstone and wackestone.

The Buffalo sandstone crops our just below the Pine Creek and to the north of the limestone outcrop. Walk along the sandstone outcrop and examine the cross bedding.

Geologic History: Environment of Deposition:

The Pine Creek represents a part of a major marine transgression associated with the general Conemaugh Group third-order transgressive-regressive unit (Busch and Brezinski, 1984). The Pine creek shales and limestone overly a large delta channel sandstone, the Buffalo sandstone. If you follow the Pine Creek shales to the north, they eventually grade into sandstone, which probably represents a delta lobe(?) prograding into marine water.

Paleogeographic map showing the region during the during Pine Creek Limestone time.

he Saltsburg sandstone represents a brief regression as a distributary channel prograded out into the shallow Woods Run sea.

Distributary Environment  (from Horne and others, 1978).

Click on the thumbnails below for pictures of the outcrops:

A view of the entire outcrop. Note the bench of Pine Creek limestone.

Close-up of the Pine Creek limestone and underlying shales. Base of Pine Creek is at top of hammer head.

View of entire section exposed at the south end of the site.

Fragmented crinoid calyx.

Flattened and disarticulated crinoid columnals, along with bryazoa fragments.

The Buffalo sandstone below the Pine Creek limestone (above right in image).

Close-up of cross-bedding in the Buffalo sandstone.

Very good fossil collecting locality. Crinoid column and calyx fragments are very common. Also found are abundant bryazoans.

 References:

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)