The Wasatchian North American Stage on the geologic timescale is the North American faunal stage according to the North American Land Mammal Ages chronology (NALMA), typically set from 55,400,000 to 50,300,000 years BP lasting. It is usually considered to be within the Eocene, more specifically the Early Eocene. The Wasatchian is preceded by the Clarkforkian and followed by the Bridgerian NALMA stages.

Definition

The age is named after the Wasatch Formation, a highly fossiliferous stratigraphic unit stretching across six of the United States from Idaho and Montana in the north through Utah and Wyoming to Colorado and New Mexico in the south.

Substages

The Wasatchian is considered to contain the following substages:

Wasatchian correlations