Where the Red Chert Grows: An investigation into a potential source of red clasts glacially distributed throughout the Puget Lowland

Abstract

Clasts of fine grained siliceous red rock or red clasts (RC) have been found on many beaches around Puget Sound, Washington by E. Cheney from the University of Washington. Cheney plotted the locations of RC and created an isoline map showing concentrations of larger RC in the Whidbey Island area. Because of the abundance of larger clasts within Puget Sound and the glacial history within the region, a likely source of RC may be located in the southwestern Cascades. Red rocks very similar to what is observed on Puget Sound beaches is described in the Canyon Creek Unit by Vance (1957) located near Verlot, WA, directly east of Whidbey Island. Thin sections of the beach cobbles obtained by Cheney were compared with thin sections from the Canyon Creek Unit to determine if it could be identified as a source of RC. Although there are many similarities between the beach cobbles and the Canyon Creek Unit, it can only be considered a plausible source for RC found on Puget Sound beaches given the amount of data collected. A more intense sampling campaign of both sources along with additional analysis methods are required to fully confirm, or deny the Canyon Creek as a source of the RC within the Puget Lowland.