Abstract
Tertiary rocks are extensively exposed in Jackson Hole, Wyoming, covering a span of time from the Paleocene to the Pliocene. The most extensive deposits most commonly seen along Pilgrim Creek are those of the Colter Formation which is Miocene in age. At the base of the Colter Formation along the east fork of Pilgrim Creek is a small exposure of Oligocene rocks, the western-most deposit of this age known in Wyoming. This deposit has been the target of research for the past several seasons.