474 



University of California. 



I Vol. 3. 



The 850-foot terrace of the Orleans Basin I will correlate 

 with the Red Blnff formation of the Great Valley. This is 

 based on the fact that the highest late Quaternary terrace of 

 the Klamath region may be traced out of the mountains, and 

 it becomes the prominent Red Bluff terrace on the northern 

 border of the Sacramento Valley. The internal structure and 

 the history involved in the Red Bluff formation have not yet 

 been thoroughly elucidated. The Red Bluff proper is compara- 

 tively old, as is evidenced by the undulating topography of most 

 of its area. North of the latitude of Sacramento it has the deep 

 red color which is characteristic of the upper Quaternary ter- 

 races of the neighboring mountains. So far as I am aware, there 

 are no Quaternary terraces higher than the Red Bluff on the 

 borders of the Great Valley. It marked the end of a long quiet 

 period and the beginning of the disturbed, terrace-forming 

 period. Taking all these facts into consideration, I believe that 

 the correlation of the Red Bluff formation with the Quaternary 

 terrace of the Klamath region is fairly safe. 



In 1902 I discussed* a system of river terraces carved on a 

 late Pliocene series in the valley of the Santa Clara River of 

 the South, in Los Angeles County. The highest, estimated at 

 400 feet above the river, marked the end of a long quiet period 

 (during which the Pliocene Basin was almost reduced to a 

 peneplain), and the begining of a terrace-forming period. On 

 the principle that the Quaternary history of the Klamath region 

 was in a general way duplicated throughout the State, I must 

 correlate this 400-foot terrace of the Santa Clara Valley in 

 Southern California with the 850-fobt terrace of the Orleans 

 Basin. Before I had gained the idea that the highest late 

 Quaternary river terraces in all portions of the State should be 

 considered equivalent in age, I had referred the 400-foot terrace 

 mentioned above, and the highest terrace of the Sierran Canons 

 of the Klamath region to the Red Bluff epoch on the basis of 

 erosion studies. 



In short, the upper division of the Sierran Canon at Orleans 

 must be referred to the Santa Clara epoch of the classification 



*' ' The Quaternary of Southern California. ' ' Bull. Dept. Geol., Univ. 

 Calif., Vol. 3, No. 1, pp. 10-11. 



