Douglas Lake Member
| Douglas Lake Member | |
|---|---|
| Stratigraphic range: | |
Holotype specimen of Chasmataspis laurencii | |
| Type | Member |
| Unit of | Lenoir Limestone |
| Underlies | nodular member of Lenoir Limestone |
| Overlies | Mascot Dolomite (Knox Group) |
| Thickness | up to 37 meters (121 ft) |
| Lithology | |
| Primary | rubble conglomerate, chert conglomerate, and black dolomite |
| Other | Shale (shaly dolomite), volcanic ash |
| Location | |
| Region | Tennessee |
| Country | United States |
| Extent | discontinuous, paleokarst fills in top of Mascot Dolomite |
| Type section | |
| Named for | Douglas Lake (Douglas Reservoir) |
| Named by | J. Bridge |
| Location | north shore of Douglas Lake, 2.4 kilometers (1.5 mi) northeast of the Douglas Dam |
| Year defined | 1995 |
The Douglas Lake Member is a geologic unit of member rank of the Lenoir Limestone that overlies the Mascot Dolomite and underlies typical nodular member of the Lenoir Limestone in Douglas Lake, Tennessee, region. It fills depressions that are part of a regional unconformity at the base of Middle Ordovician strata, locally the Lenoir Limestone, that separates them from the underlying Lower Ordovician strata, locally the Knox Group.