Golden Valley Formation
| Golden Valley Formation Stratigraphic range: late Paleocene to early Eocene |
|
|---|---|
| Type | Geological formation |
| Sub-units | Bear Den Member, Camels Butte Member |
| Underlies | White River Group |
| Overlies | Sentinel Butte Formation |
| Thickness | up to 122 metres (400 ft) |
| Lithology | |
| Primary | Claystone, mudstone, siltstone, sandstone |
| Other | Lignite, conglomerate |
| Location | |
| Region | North Dakota |
| Country | United State |
| Type section | |
| Named for | Golden Valley, North Dakota |
| Named by | Benson and Laird, 1947 |
The Golden Valley Formation is a stratigraphic unit of late Paleocene to early Eocene age in the Williston Basin of North Dakota. It is present in western North Dakota and was named for the city of Golden Valley by W.E. Benson and W.M. Laird in 1947. It preserves significant assemblages of fossil plants and vertebrates, as well as remains of mollusks and insects.
The Golden Valley Formation is present as a series of outliers in western North Dakota. It is underlain by the Sentinel Butte Formation and unconformably overlain by the White River Group. It reaches thicknesses of up to 122 metres (400 ft) and is subdivided into two members: the Bear Den Member (lower) and the Camels Butte Member (upper).
The base of the Bear Den Member consists of kaolinitic claystone, mudstone and sandstone that weather to white, light grey, orange, and purple. These are overlain by grey or brownish carbonaceous sediments and, in some areas, a bed of lignite (the Alamo Bluff lignite). In places the sequence is capped by a siliceous bed (the Taylor bed) that represents a weathering surface or paleosol. The Bear Den Member reaches a maximum thickness of about 15 metres (50 ft).
The Camels Butte Member consists of montmorillonitic and micaceous claystone, siltstone, lignite, poorly cemented sandstone and conglomerate. The upper part includes a massive fluvial sandstone that caps many of the major buttes in southwestern North Dakota. The Camels Butte Member reaches a maximum thickness of about 107 metres (350 ft).
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