76 SOUTHERN CALIFORNIA ACADEMY OF SCIENCES. 



Mr. Oscar Hershey, of Berkeley, has also done some work in Southern California. 

 His paper on the Quarternary * and another of later date, on earlier strata** present 

 modestly an outline of the general structure, which is more complicated and inter- 

 esting than has been usually understood by geologists unfamiliar with the region. 

 Numerous movements of elevation and subsidence, which have extended over vast 

 areas from the Rocky Mountains to the Pacific Coast, have been almost overlooked 

 until within recent years. The labors of various members of the U. S. Geological 

 Survey and of the staffs of the Universities at Berkeley and Palo Alto have been 

 fruitful of results. And some good work has been done also by the State Min- 

 eralogists's corps in different years, particularly by Cooper, Watts and Bailey. But 

 there is a dearth of investigators in Southern California. We have competent 

 men in the local colleges and it should become one of the main objects of the 

 Geological Section of the Academy of Sciences to organize and sequester the 

 records, which abound in this locality, of geologic phenomena of great interest, 

 easily studied. Hershey shows, in his paper on the Quaternary, that "aside from 

 the marine terraces pretty thoroughly discussed by Lawson,t FairbanksJ and 

 Smithtt, and the associated sands and gravels studied by Arnold, the Quarternary 

 of Southern California is virtually a virgin field." Mr. Ralph Arnold's paper 

 was read last December before the Cordilleran Section of the Geological Society 

 of America, but has not yet fully appeared in type. Only a few salient points in 

 the discussion, can here be lightly touched. Once more the amiable controversy 

 between field geologists and office paleontologists, which Mr. Bailey Willis has 

 recently been attempting to clear up in a measure, crops out in the effort to define 

 a conventional break between Pliocene and Pleistocene strata in California. There 

 is a profound orographic element which is not always represented by abrupt changes 

 in fossils, and Mr. Hershey justly claims that physical criteria are of greater mo- 

 ment in recent stratigraphy than any variations in faunal types which could pos- 

 sibly occur under the known conditions of those closely related periods. On this 

 score he demurs in part to the correlation tables proposed by Arnold and others. 



The skeleton of our local geology may thus be broadly summarized: The 

 Sierra Madre-San Bernardino range, and the Tehachapi range — uplifted to some 

 extent as a part of the Sierra Nevada orographic disturbance, and probably rising 

 more or less gradually for a long continued era of pre-Tertiary times, — fur- 

 nished by erosion a vast accumulation of detritus which was carried downward 

 to the ocean, forming thick sedimentary terranes through the Tertiary Period. 

 Moderate disturbances in earlier epochs, accompanied by volcanic outbursts, cul- 

 minated at the close of the Pliocene in the great movement above mentioned, which 

 has elevated portions of the old Pliocene plain from 3000 ft. to 8000 ft. Mr. 

 Plershey traces much of the Sierra Madre uplift also to this epoch, and he shows 

 that the great Antelope Valley, north of these mountatins, was separated from 

 that by faulting which occurred at the beginning of the Quarternary. Since then 

 our local area has been mainly rising by successive minor throes until we have 

 numerous terraces of Ouarternary and recent beach gravels and alluvial deposits. 



This is the coast border which has for long been gradually reclaiming from 

 the sea. Professor Hershey has begun the work of unraveling the skein of super- 

 ficial layers and he outlines five epochs of Ouarternary (Pleistocene) time, as be- 

 low (the first being earliest) : 



1. Santa Claran Epoch, characterized by erosion with land level normal. 



2. Red Bhtff Epoch, characterized by deposition, land level below normal. 



3. Los Angelan Epoch, erosion of normal land surface. 



*The Quaternary of Southern California. Bull. Dept. Geol., Univ. of Cal., No. 

 I, p. I. 



**Somc Crystalline Rocks of Southern California. American Geologist, V^ol. 

 XXIX, No. 5, May, 1902, p. 273. 



Voc. c'i.. ante. 



tOsc'llat-'ons of the Coast of Calif orn in during the Pliocene and Pleistocene. 

 Dr. H. W. Fairbanks. Amer. (ieol., Vol. XX, Oct., 1897, pp. 2:3-245. 



tt.4 Topographic Study of the Islands of Southern California. W. S. Tangier 

 Smith. Bull. Dept. Geol. Univ. of Cal., Vol. 2, No. 7, Sept., 1900, pp. 179-230. 



