SOUTHERN CALIFORNIA ACADEMY OF SCIENCES. 75 



record so legible. Nowhere will greater discoveries reward the enthusiastic geologist. 

 Yet how few have been the workers in this field ! How scant are the opportunities 

 afforded by State aid for systematic research!" 



The field is large enough and enticing enough to engage the attention of numerous 

 active workers for years to come. Speaking more particularly for Southern Cali- 

 fornia, we are very deficient in literature bearing upon local geology. Professor 

 I^awson, in the quoted paper, shows that the existing coastal margin has been up- 

 lifted in modern time from 800 ft. to 1500 ft., from the Golden Gate to San Diego, 

 and that this movement was of wide extent inland, but of less degree in the "Valley 

 of California," between the coast area and the Sierra Nevada. 



Dr. Lawson's studies confirm those of Dr. A. S. Cooper, announced as early as 

 1863, and they also emphasize the fact, not always properly appreciated, that the 

 whole region west of the Great Basin, or Plateau, has been and is now an area of 

 erogenic displacement. The evidences afforded in numerous mines in Nevada, Ari- 

 zona, California and Mexico, and in surface studies over a wide expanse in the same 

 field, all point conclusively to the same generalizations. 



The late Dr. E. W. Claypole had made equivalent deductions from his work in 

 the Sierra Madre,* and the writer has verified and slightly extended the application 

 in unpublished work along the coast from Santa Barbara to Santa Monica and in the 

 low coastal ranges farther inland. 



The theory of "isostasy," or equilibration, affirms that elevation and subsidence 

 are due merely to adjustment of the equilibrum of a floating crust, from which follows 

 the idea that sedimentation has caused the subsidence of large tracts and that erosion 

 has been responsible for regional elevation in great measure. Dtitton** carries the 

 theory to its limit in suggesting that even volcanic action may result from the same 

 isostatic tendency. The principle is as old as the writings of L,yell and Herschell, 

 and it has been amplified and reiterated by the leading American geologists until very 

 recently. The late eruption in ?,Iartinique and St. Vincent. West Indies, are probably 

 rightly attributed largely to this cause in their local effects. LeConte, in 1859, and 

 other eminent geologists in later years, have given adherence to this explanation of 

 vast earth movements, but in 1884 and subsequently Dr. LeConte sided with a new 

 school of students who have come to regard this cause of undulation in the crust as 

 of minor importance. These hold that "the converse proposition is much more true, 

 viz. : that subsidence is the cause and necessary condition of sedimentation, and ele- 

 vation the cause of exceptional erosion. "t A very interesting paper, published in 

 1896, by F. I^eslie Ransomei, criticises the theory of isostasy as applied to the region 

 between the Sierra Nevada and the Coast ranges. The discussion cannot be narrowed 

 to this region, however, and the work of Lawson in the coast areas is quoted by Ran- 

 some in partial support 'of his contentions. We have here a striking illustration of 

 our initial thesis; for, as Dr. Claypole remarks, in the paper previously cited, "geol- 

 ogists who have worked principally in the East witness with surprise the enormous 

 development and the excessive diastrophism exhibited by Tertiary and even very late 

 Tertiary strata in the West, and these characters are as well seen in California as in 

 any other Western state. 



It is not proper to leave this subject without mention of Dr. Lawson's reconnois- 

 sance north of the Golden Gate, where he obtained evidence of very similar history 

 in the recent elevation of the coast. H 



*Sierra Madre near Pasadena. E. W. Claypole. Paper read before the Cordil- 

 leran Section, Geol. Soc. America. Abstract published in Bull. Geol. Soc Am., Vo.. 

 12, igoo. 



**Haivaiian Volcanoes. 4th annual report, U. S., Geol. Surv., 1884, pp. 190-195- 



tr/iff Elevation of the Sierra Nevada, Amer. Journ. Sci., Vol. CXXXII, 1886, 

 p. 167. 



tThe Great Valley of California. Bull. Dept. of Geol, Univ. of Cal. Vol. i. 



No. 14, p. 371- „ , 



tiThe Geomorphogeny of the Coast of orthern California. Bull. Dept. Geol., 

 Univ.' of Cal., Vol. i,^No. 8, p. 241, Nov. 1894. 



