Geological Survey Professional Paper 329 Reconnaissance of the Geomorphology and Glacial Geology of the San Joaquin Basin, Sierra Nevada California

François E. Matthes' reconnaissance of the San Joaquin Basin, situated in the central part of the west slope of the Sierra Nevada, California, in the summers of 1921, 1923, and 1927, was undertaken for the United States Geological Survey in order to extend southeastward the studies made earlier in the Yosemite region, and to test the soundness of conclusions reached in the Yosemite region regarding the geomorphologic development and the glaciation of that area, and to determine their bearing on the history of the Sierra Nevada in general.

In ensuing years, Matthes completed his monumental "Geologic History of the Yosemite Valley," published in 1930, and a number of shorter papers on the Sierra Nevada, but pressure of other duties prevented him from giving the San Joaquin studies the continuous and undivided attention necessary for completion of a report. For this reason his only published references to the area were a few brief notes, mainly in abstracts. He did return to the San Joaquin studies repeatedly during intervals between other assignments, and in time, all but finished the glacial map and the profiles, and wrote some sections of the text with various stages of completeness. But as distractions from the project multiplied rather than diminished, he came to regard the completion of the San Joaquin report as an undertaking which would have to await the leisure of retirement years. The urgent needs of World War II made necessary his continuance with the Geological Survey beyond the usual age of retirement, and he did not leave government service until 1947, when he was 73 years of age. He died a year later, before he had resumed work on the San Joaquin report.

In the Geological Survey, hope was still held that the manuscript material left by Matthes might provide the basis for a report which would embody the substance of his findings even though it might not attain quite the form or comprehensiveness that he contemplated. I was asked to explore this possibility, and my efforts to produce the desired report have resulted in the present publication.

An outline of Matthes' projected report, fortunately preserved among his papers, has been closely followed. The principal sources have been, of course, Matthes manuscript materials, which range in their completeness from mere jottings of ideas and fragments of text, in hand-written rough draft, to two sections of the chapter on "Geomorphology," which were typed in essentially finished form. For many topics in the outline, manuscript material was wholly lacking, presumably because Matthes had not yet had opportunity to begin work on them. It was possible to fill in most of these gaps from Matthes' field notes, diaries, maps, profiles, and annotations in his photographic albums, as well as from his published references to this and adjacent regions. It is evident that these topics would have received fuller development at the hands of Matthes himself, but the procedure followed provided the only way by which, under the circumstances, a reasonably complete and coherent report could be achieved.

I possessed some previous acquaintance with the region, and this was supplemented by a brief period (July 11-21, 1952) spent in the field, refreshing my memory of geomorphic and glacial features and checking a number of doubtful localities.

Some gaps remain. From Matthes' outline it is evident that he intended to write on a few topics concerning which little or no information is to be found even in the field notes. The most important of these topics are "earlier conceptions of geomorphologic development of the west slope of the Sierra Nevada," "glacial sculpture," and "postglacial changes." These omissions, while regrettable, are perhaps less serious than at first appears, for they relate to regional problems that Matthes has considered in publications dealing with other sections of the Sierra Nevada. Matthes may have intended to discuss the bearing of the restored Tertiary profiles of the San Joaquin River on the problem of the amplitude of the Sierra Nevada uplifts, but the subject is not specifically indicated in his outline and he left no written material relating to it.

When it is recalled that Matthes worked intermittently on this report for almost 30 years, it is evident that on some subjects his views must have undergone change while the work was in progress. Some sections had been rewritten repeatedly, evidently after considerable lapses of time, and a critical choice had to be made between versions of text which covered the same subject matter but with differences of viewpoint, treatment, or emphasis.

It would be desirable for the benefit of the reader, if the exact derivation of every part of this report could be indicated, but from what has been said concerning the manner in which the report as a whole was synthesized, it is evident that this is impossible. The reader may assume, however, that essentially the entire report is based on manuscript materials, field notes, and other unpublished sources left by Matthes except those sections for which published sources are cited.

FRITIOF FRYXELL