164 



PROCEEDINGS OP THE AMERICAN ACADEMY, 



laud. The cliff, rock bench and terrace, beach, bar, etc., may all be 

 found elevated above the sea in this initial stage of the new cycle. A 

 good example of a recently elevated shoreline is not known to the writer. 

 Figure 4, giving a portion of San Clements island, California (C. S., 

 607, 671, now 5100, 5127), shows several elevated former shorelines, 

 the last formed being nearly in their initial stage. For detailed descrip- 

 tion of these cliffs and terraces, resulting from periods of comparative 

 quiet in a series of progressive uplifts, consult the account of the island 

 by Professor Lawson.* 





FiGDRE 4. Elevated Former Shorelines on San Clemente Island, California. 



One of the features characteristic of progressive uplift is clearly shown 

 upon this map, namely, the more advanced stages of stream development 

 farther and farther inland from the shore. The valleys widen as one 

 ascends from the western shoreline, and are shallower on the lower ter- 

 races, as is seen on the map. The streams have had more time in which 

 to dissect the higher terraces. 



The sequential forms, developed at each level on this island, indicate 

 extreme youth at the time of each uplift ; therefore the coastal plain 



* Bull. Dept. Geol., Univ. of Cal., 1893, I. 128-133. 



