Evidence of tectonic stability along the middle Columbia River, Washington, in Quaternary time

Observations of outcrops and Pleistocene-age surfaces along the Columbia River, between Priest Rapids Dam and Richland, Washington, provide evidence for recent tectonic stability that may be significant to planning of earthquake-sensitive engineered structures in the vicinity. Apparent continuity of layering in the Yakima Basalt (Miocene), Ringold Formation (Pliocene), and calcrete capping much of the Ringold Formation (more than 100,000 yrs old), and the absence of appreciable deformation of several large, smooth, late Pleistocene surfaces indicate that there has been little or no deformation along much of this part of the Columbia River since these rocks and surfaces were formed.