| Table 3. Interpreted stratigraphic relations at Stop 14 and proposed depositional environments extrapolated from Schwab (1971, 1972), Simpson and Eriksson (1989) and interpreted tectonic regimes from Wehr and Glover (1985, table 2) and Fichter and Diecchio (1986, fig. 1) | |||
Unit |
Lithology |
Environment |
Tectonic regime |
|---|---|---|---|
| Harpers Formation | Dark silty shale and thin sandstone | Shallow marine | Transgressive |
| Weverton Formation | Crossbedded arkosic and conglomeratic sandstones | Meandering fluvial Braided fluvial |
Trailing margin deposition |
| Loudoun Formation | Tuffaceous shale and conglomerate | Alluvial fan-rift valley | |
| Catoctin Formation | Basaltic lava flows | Extensional, rift volcanics | Extension and rifting |
| Swift Run Formation | Arkosic sandstone and varved shales | Rift valley | |