Thumb member
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TypeFormation
Unit ofHorse Spring Formation
UnderliesBitter Ridge Limestone
OverliesRainbow Garden member
| Thumb member | |
|---|---|
| Stratigraphic range: Neogene | |
| Type | Formation |
| Unit of | Horse Spring Formation |
| Underlies | Bitter Ridge Limestone |
| Overlies | Rainbow Garden member |
| Lithology | |
| Primary | sandstone |
| Other | conglomerate, gypsum |
| Location | |
| Coordinates | 36°37′30″N 114°56′45″W / 36.62500°N 114.94583°W |
| Region | Nevada |
| Country | United States |
| Type section | |
| Named for | Thumb valley north of Lake Mead, Clark Co, NV[1] |
| Named by | Chester R. Longwell, 1952[1] |
The Thumb member of the Horse Spring Formation is a geologic member in Nevada. It contains sandstone with beds of conglomerate and gypsum in the Neogene period.[2]
