| Shadow Lake formation | |
|---|---|
| Stratigraphic range: Middle Ordovician | |
| Type | Geological formation |
| Unit of | Black River & Simcoe Groups |
| Underlies | Gull River Formation |
| Overlies | Grenville basement Loysburg Formation |
| Thickness | 0–10 m (0–33 ft)[1] |
| Lithology | |
| Primary | Sandstone, conglomerate |
| Other | Siltstone, shale |
| Location | |
| Region | Ontario Pennsylvania |
| Country |  Canada United States |
| Type section | |
| Named for | Shadow Lake |
| Named by | Liberty |
| Year defined | 1969 |
The Shadow Lake formation is a geological unit that crops out in Southern Ontario, Canada and northern Pennsylvania, United States.[2] The shaly sections act as a caprock to petroleum reservoirs.
- ^ Cite error: The named reference
OGS_p8was invoked but never defined (see the help page). - ^ "Geology of the Southwestern Ontario District". Ontario Ministry of Northern Development and Mines. 25 November 2011. Retrieved 14 April 2012.