i88 STUDIES FOR STUDENTS 



cut cliffs reaching an elevation on San Clemente of 1,320 feet. These 

 according to Lawson are the most remarkable and most magnificent 

 examples of this type of topography which it has ever been his good 

 fortune to behold. He further remarks that such features one might 

 expect to find on a planet, which after their formation, had become 

 stripped of its atmosphere.^ Similar terraces are found on the coast of 

 northern California, and Lawson regards the whole as due to epeiro- 

 genic movement which he considers as sufficiently simultaneous to 

 inaugurate a new geomorphic cycle which is in a nearly uniform state 

 of advancement all along the coast. ^ Under the rainy climate of the 

 coast of northern California, but especially of Oregon, these raised 

 beaches are still conspicuous ; but it is noteworthy that they have not 

 called forth such descriptions as those of the arid portions of the coast 

 line, while Diller speaks of the raised beaches of the Oregon coast 

 as being less distinct above eight hundred feet.^ 



It would seem from the above that on the Pacific Coast is an ideal 

 region for comparing the rates and kinds of erosion upon the same 

 initial earth forms, offering an attractive problem for physiographic 

 study. 



In conclusion, from the preceding resume it would appear that 

 an arid climate is an important contributory factor in the develop- 

 ment of plains of marine denudation, a factor which so far as the 

 writer is aware has not previously entered into the discussion of the 

 problem of the relative development of plains of subaerial and marine 

 erosion. 



Finally, from the discussions under this and preceding topics, the 

 following estimates may be made of the relative rates of erosion under 

 different climates upon average rock materials in a state of topographic 

 maturity. From such a brief study such a statement is clearly nothing 

 but an estimate. Proceeding from what is thought to be the less 

 rapid to the more rapid they would be — 



I The Post-Pliocene Diastrophism of the Coast 0} Southern California, Bulletin 

 of the Department of Geology, University of California, Vol. I, No. 4, 1893, p. 

 129. 



= The Geomqrphogeny of Northern California. Bulletin of the Department of 

 Geology, University of California, Vol. I, No. 8, 1894, p. 270. 



3 Coos Bay Folio, U. S. Geological Survey, p. i, 1901. 



