Gettysburg Formation
The Gettysburg Formation is a mapped bedrock unit consisting primarily of sandstones, conglomerates, and shales.
| Gettysburg Formation | |
|---|---|
| Stratigraphic range: Late Triassic | |
Outcrop of Gettysburg Formation along Conewago Road in York County, Pennsylvania, facing east from the bridge over Conewago Creek | |
| Type | sedimentary |
| Unit of | Newark Supergroup |
| Sub-units | Heidlersburg member, Arendtsville fanglomerate lentil, Elizabeth Furnace conglomerate member, Conewago conglomerate member |
| Overlies | New Oxford Formation |
| Thickness | 5000 m (16,000 feet) |
| Lithology | |
| Primary | sandstone, conglomerate |
| Other | shale |
| Location | |
| Extent | Pennsylvania, Maryland |
| Type section | |
| Named for | Gettysburg, Pennsylvania |
| Named by | Stose and Bascom, 1929 |
The Gettysburg Formation was first described in the Gettysburg area of Adams County, Pennsylvania in 1929, and over the following decade was mapped in adjacent York County, Pennsylvania and Frederick County, Maryland. It was then typically called the "Gettysburg shale," and was described as "thick red shales and soft red sandstones." The majority of this early mapping was done by G. W. Stose, A. I. Jonas, and Florence Bascom. Later workers described it as "Red, medium- to fine-grained sandstone and shale."
The rock unit was formalized into a Formation in 1963 by J. D. Glaeser. Glaeser re-mapped some areas previously mapped as the Gettysburg Formation to the Hammer Creek Formation.
A major groundwater resources study of the Gettysburg Formation and other formations of the Newark Supergroup in Pennsylvania was published by Charles R. Wood in 1980.