Kootenai Formation

Kootenai Formation
Stratigraphic range: Aptian-Albian
Typical Kootenai Formation in a roadcut. Sunburst Sandstone Member overlying the red informally named member 2. Cascade County, Montana.
TypeGeological formation
Sub-unitsCut Bank Sandstone Member, Moulton Member, Pryor Conglomerate Member, Sunburst Sandstone Member.
UnderliesBlackleaf Formation
OverliesMorrison Formation unconformably
Thickness75 to 195 metres (246 to 640 ft)
Lithology
PrimaryNonmarine mudstones, siltstones and sandstones
Location
RegionMontana, Idaho
CountryUnited States
Type section
Named forKootenai Tribe who occupied western Montana and Alberta

The Kootenai Formation is a Lower Cretaceous geologic formation. The Kootenai was deposited in a foreland basin east of the Sevier thrust belt in western Montana. The lithology consists of a basal conglomerate with overlying non-marine sandstones, shales and lacustrine limestones.[1]

The most common fossils found within the Kootenai Formation are gastropod, ostracod, and pelecypod shells. Dinosaur remains are among the fossils that have been recovered from the formation, although none have yet been referred to a specific genus.[2]