Coasts 



17 



Figure 14. Cretaceous sandstone at Whale View Point, LaJolIa, drilled by chitens that make elliptical hole by bio- 

 chemical action. Photographed April 1943. 



by the increased alkalinity of the water dur- 

 ing the night. During the daytime, how- 

 ever, the plants require more carbon dioxide 

 for photosynthesis than is produced by respi- 

 ration of both plants and animals; therefore 

 the total carbon dioxide content of the water 



decreases below that of the water which 

 entered the pool. As a result of increased 

 temperature, salinity, and pH, calcium car- 

 bonate is often deposited during the day- 

 time. Calcium carbonate deposited from 

 capillary films of water extending outward 



Figure 15. Miocene (?) lime- 

 stone bored by worms from 

 depth of 720 feet in San Pedro 

 Sea Valley (x 1). Similar bor- 

 ing also occurs in shales from 

 the inter tidal zone. 



