Lawson. | 



Post- Pliocene Diastrophism. 



'39 



the sea-cliffs of San Pedro and San Clemente. Their excessively 

 rapid recession is shown in their relation to the canons of the island. 

 Where the sea-cliffs cut across the mouth of a canon, it is frequently 

 apparent, particularly on the southwest side of the island, that the 

 recession of the cliff has been much more rapid than the rate at 

 which the streams can sink their trenches or cut back their gorges. 

 This results in a topographic phenomenon not observed by the 

 writer anywhere else on the California coast. The valley or canon 

 bottoms, instead of sloping to the sea level, end abruptly at the 

 brink of a sheer cliff, over which the stream falls 30, 50, 80, or 100 

 feet, etc., as the case may be, without any serious pretense of a 

 stream-cut gorge in the face of the cliff. This can only be due to 

 an excessively rapid recession of the sea-cliffs relatively to the 

 trenching of the canons. And in this fact we have again evidence 

 that Santa Catalina Island is sinking beneath the waters of the 

 Pacific. What is the measure of the depression which has already 

 been effected? — Twenty-five miles to the north San Pedro Hill has 

 been demonstrated to have participated in an uplift of at least 1,240 

 feet. Twenty-five miles to the south San Clemente has risen from 

 the ocean through 1,500 feet. What relation exists between the 

 depression of Santa Catalina and the uplift on either side ? The 

 answer to this question can only be a tentative or speculative one. 

 The facts, however, strange as they appear, may be readily verified, 

 and are not more wonderful than many other, perhaps less patent, 

 but still indubitable phenomena of a like kind which may be read 

 in the physiography of Southern California. 



CARMELO BAY. 



In a former paper* the writer has shown that in the vicinity of 

 Carmelo Bay there is abundant evidence of the recent elevation of 

 the coast to an extent of at least 800 feet. The evidence is of the 

 same character as that described in the present paper for other 

 parts of the coast. Although no evidence of uplift exceeding 800 

 feet was observed within the limits of the area then examined and 

 described, it is very probable that on the high ground back of 

 Carmelo Ray still higher strand lines will be found. 



*This Bull., p. 46, et. seq. 



