A widespread sequence of Pennsylvanian and Permian sedimentary rocks bounded above and below by unconformities; deposited during a transgressive-regressive cycle of the Absaroka Sea.

The Absaroka sequence was a cratonic sequence that extended from the end of the Mississippian through the Permian periods. It is the unconformity between this sequence and the preceding Kaskaskia that divides the Carboniferous into the Mississippian and Pennsylvanian periods in North America.