272 CALIFORNIA ACADEMY OF SCIENCES. [Proc. 3D Ser. 



type and there is no evidence that they ever extended into 

 the canyon below. If v^e admit that the canyon of the 

 North Feather was cut out by ice, we must also admit that 

 it was at such a remote period that no remains of an}^ mor- 

 aines left by the ice exist at the present time. This makes 

 the case improbable inasmuch as moraines could hardly fail 

 to be left in the foothill region or on some of the level 

 topped spurs that border the canyon. 



Some evidence will be hereafter presented which sug- 

 gests that the Glacial Period began in the Sierra before the 

 canyons were cut to their present depth. In other words, 

 the Sierran and Glacial Periods overlapped ; but, taken in a 

 general way, it may be stated, with some confidence, that 

 the Glacial Period in the main followed the Sierran Period 

 of erosion. There is apparently positive evidence as to this 

 sequence in Sawmill Canyon, lying northwest of Independ- 

 ence, Inyo County. Sawmill Creek rises upon the east side 

 of the summit line of the Sierra Nevada and cuts through 

 the east steep escarpment to the plains below. After the 

 canyon was cut by the stream there occurred a volcanic 

 outburst, and the lava from this source flowed down the 

 canyon. This lava is of the same kind and probably of 

 exactly the same age as the lava of the little cinder-cones 

 and lava flows which lie along the east base of the 

 range between Independence and Big Pine. These cinder- 

 cones still retain their original contours and are, without 

 much doubt, of middle Pleistocene age. After the flow of 

 lava in Sawmill Canyon took place, the glacier of the can- 

 yon reached its maximum, and the largest and apparently 

 the oldest moraine of Sawmill Canyon lies mostly on top of 

 this flow. At Mono Valley, and in some other smaller val- 

 leys to the south, the glaciers of the Sierra Nevada protruded 

 as tongues out into the valleys and left beautifully formed 

 moraines on their retreat. In no portion of Owen's Valley, 

 from Big Pine to Owen's Lake, did the glaciers ever extend 

 on to the detrital slopes, much less to the level of the main 

 valley. So far as present evidence goes, if we believe these 

 canyons to be cut by glaciers, we must suppose that the 



