Geologic Unit: Arapien

Usage:

Arapien Shale (UT*)
Arapien Formation (UT*)

Subunits:

Twelvemile Canyon Member (UT).

Geologic age:

Middle Jurassic (Callovian)*

Type section, locality, area and/or origin of name:

Type area: Arapien Valley, [Sanpete Co., central UT], which lies parallel to base of Wasatch Plateau about 6 mi southeast of Gunnison. Formation is typically, if not completely exposed, on west side of valley (Spieker, 1946).
Principal reference locality: along east flank of Sevier Valley, from near Sigurd [Sevier Co.] on south to Sterling [Sanpete Co.] on north, central UT (Witkind and Hardy, 1984).
Reference locality: along west and north flanks of San Pitch Mountains, from near Little Salt Creek to south to Salt Creek on north, [Juab Co., central UT] (Witkind and Hardy, 1984).

AAPG geologic province:

Great Basin province*
Uinta basin*
Wasatch uplift*