Geologists have long known of the presence of Pleistocene and Recent lava flows and cones around the southern half of Clear Lake, California, but very little has been written regarding these features since the pioneer work of Becker,1 although several papers have appeared in reference to the quicksilver deposits at Sulphur Banks. Lack of suitable base maps has inhibited geologic mapping. However, a soil survey was published recently by Carpenter, Storie, and Cosby,2 and they prepared a base map by means of plane-table traverses, using an automobile speedometer for measuring distances. Unfortunately, no topography is expressed on this map, but the location of the roads and shore of Clear Lake are accurately shown. Using their map as a base, aided by the topographic maps of the War Department, the writer mapped the volcanic rocks. This paper covers the results of the study.
Clear Lake lies in the midst of . . .