SKCT. 3] ORGANIC TKANSPOIITATION OF MARINE SEDIMENTS 781 



Table I 



Source of Gastroliths in some California Sea-Lions. Based on Autopsies by 



Arthur L. Kelly and K. O. Emery 



Area where sea-lion 

 was killed 



Number of sea-lions Source of stones same 

 having stones as at collection site 



North Coronado Island, Mexico" 

 South Coronado Island, Mexico <» 

 San Nicolas Island, California^ 

 La JoUa, California <^ 



11 

 5 

 3 

 5 



8 

 5 

 2 

 4 



« North Coronado Island has only Miocene red sandstone, whereas South Coronado 

 Island, only 3 km distant, has only Miocene yellow sandstone and a conglomerate 

 composed of metamorphic and igneous rocks. 



^ San Nicolas Island is entirely Eocene shale and sandstone. 



c La Jolla gravel beaches are mostly of a Mesozoic metavolcanic rock reworked 

 from Eocene conglomerates in sea cliffs. 



Fig. 3. Dissected stomach of sea-lion {Zalophus califoniianus) taken at Coronado Islands, 

 Mexico, by A. L. Kellj'. Largest stone is about 5 cm long. All are well romided and are 

 of Middle Miocene sandstone similar to that of which the islands are composed. 



up the stones locally. Where identifiable the stones are mostly of local types, 

 as shown by Table I, indicating that the sea-lion probably does not carry stones 

 very far or very long. This conclusion is verified by observations that in zoo 

 tani;s stones are picked up after meals and regurgitated a few hours later, and 

 by the fact that of 22 fur seals collected in the open sea by Austin and Wilke 



