Overview: The Chemehuevi Formation along the lower Colorado River

A distinctive set of fine-grained deposits occurs throughout the lower Colorado River Valley, extending from just below the mouth of Grand Canyon to well into the river delta below Yuma, AZ (Figure 1), an along-channel distance of over 700 km. Upstream of Parker, Arizona, the deposits consist of scattered erosional remnants up to 150 m above the modern floodplain. Below Parker, they occur in isolated outcrops but also underlie large continuous terraces such as Parker Mesa, Palo Verde Mesa, and Yuma Mesa. These deposits form the Chemehuevi Formation of Longwell (1936).