Abstract
Approximately 14 million years is thought to have elapsed between the laying down of the last flow of most of the Columbia River Basalts and the deposition of the wind-blown glacial silts of the Palouse soil (Baksi 1989, Fryxell and Cook 1964). If 14 million years were involved, the amount of erosion should be profound, cutting down into many basalt beds of the Columbia River Plateau. The purpose of this research was to examine this contact for evidence of 14 million years of erosion.