Washington Coastal Geology Between the Hoh and Quillayute Rivers

Rau, Weldon

A review of geologic processes and events as revealed by the rock formations and deposits of the Washington Coast - with historical notes and hiking information. An awareness of the many facets of nature is often heightened by a visit to the wilderness coast of Washington. Rock formations of the earth's crust and debris deposits from these formations are not only a major part of, but form the foundation for, the coast's natural setting. Many hikers have, no doubt, wondered about these formations and rock deposits and the processes that formed them. To the geologist, such questions are a challenge. Like the pages in a book, rock strata of the present-day Washington coast reveal to the geologic interpreter an incredible sequence of geologic events that, over epochs of time, has resulted in rocky headlands, offshore sea stacks, and rock debris bluffs. The purpose of this report is to present the coastal geologic story. Hopefully it will be of interest not only to students of geology but also to those readers with only a general curiosity for natural sciences. The illustrations and accompanying captions alone tell a geologic story that many may find of interest. The text, in two parts, develops the story more fully. Part I deals with the geologic processes and events that have resulted in the forming and distribution of the coastal rock formations. Part II is designed as a beach guide where the geology of individual segments of the coast is discussed starting in the Hoh River area and concluding at La Push. During the course of field investigations, many historical events were brought to the attention of the author. Some of the more interesting and geologically related appear as historical notes throughout the report. Also, general hiking conditions and trail data are presented in the appropriate sections of Part II. This report complements Bulletin 66 of the Washington Division of Geology and Earth Resources on the geology of the coastal area south of the Hoh River. Similarly, the present report is an outgrowth of geologic mapping and related research conducted by the author in the coastal area during the past 10 years. These studies have provided basic knowledge about rock types and distribution and geologic structures of the area—data essential to a scientific evaluation of the mineral and petroleum potential of this and adjacent offshore areas. It is the hope of the writer that, as a byproduct of these studies, the present publication will provide the nonscientific reader a useful and enjoyable guide to the geology and related processes of one of Washington's wilderness coastal areas.