Geological Survey Professional Paper 504—A Glacial Reconnaissance of Sequoia National Park California

The field data upon which this report is based were gathered in the course of three field seasons devoted wholly or in part to a reconnaissance of Sequoia National Park for the U.S. Geological Survey. The initial fieldwork was done in 1925 between June 9 and July 15. For the next decade the author's research was diverted to other sections of the Sierra Nevada, but in 1935 he resumed work on Sequoia National Park—this time at the request of the National Park Service and with the effective cooperation of that agency—with a view to completing a systematic reconnaissance. In that year he spent the period from July 8 to December 18 in the field, and in 1936, during the interval from May 27 to July 15, he concluded the project.

Lawson (1904) was the first to give a comprehensive sketch of the geomorphology and glacial geology of Sequoia National Park, and his classic report provided an excellent insight into the mode of development of the major landforms of that region through successive cycles of erosion and through glaciation. Some details on the glaciation of the Mineral King region were provided by Knopf and Thelen (1905). But the need for more complete information on the genesis of the landscape of the entire park—for the scenic features of this park are so exceptional as to be secondary only to the "Big Trees" which give it name—led to the joint sponsorship of the reconnaissance reported in this and previous papers (Matthes, 1937, 1938, 1947, 1950a).

Necessarily, because of the mountainous character of the tract, the physical difficulties which it offers to travel—especially through its wilder parts—and, also, because of the shortness of the working season in the High Sierra portion, much of which is above the timberline, the survey could be only of a preliminary nature. It will readily be understood that the interpretations which resulted are in part tentative and in need of verification by future, more intensive studies. Nor did the reconnaissance cover all the different aspects of the geology with equal thoroughness. Particular attention was given to the evolution of the landforms, and relatively little time was devoted to the examination of the different types of rock that occur within the area. There are so many different formations, and these are so complexly related to one another, that to map them individually and study the petrologic character of each of them would alone have required several field seasons. Some of the results of the reconnaissance have already been published, particularly those pertaining to the geomorphological features. In the present report, additional results are set forth, especially with reference to the character and distribution of the ancient glaciers which occupied Sequoia National Park during the various stages of the Pleistocene Epoch.

The author wishes to thank officials of the National Park Service for the support they gave this survey and for their warm interest in it. While the fieldwork was in progress, staff members of Sequoia National Park were generous with their time and assistance on many occasions and in many ways. Thanks are in order to several individuals who provided illustrations which appear in this report (all photographs not taken by the author have been credited to those who furnished them). The University of California Press freely gave permission to quote extensively from its publication, "Sequoia National Park: a Geological Album" (Matthes, 1950a). Finally, grateful appreciation is expressed to Clyde A. Wahrhaftig for critical reading of the manuscript and for the constructive suggestions that served to improve its effectiveness.