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CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



of shells, a well preserved large gasteropod, and numerous 

 claws of a crustacean. These beds continue down the river. 

 A bluff opposite San Fernando shows: 



Feet. 



Reynosa 20 



Yellow clay 20 



Yellow sandy clay with many fossils 4 



Cross-bedded sandstone 30 



The river here runs, south almost with the strike of the 

 beds ; thus the same or similar beds are seen for three or four 

 miles down-stream, when the river again swings east. Here 

 the clayey sands seen at the falls above the Pecten bed carry 

 not only the large gasteropod and crustacean claws, but gra- 

 hamite and fragments of lignite also. Hills a mile east of this 

 locality are composed of soft yellowish sandstone and clay 

 beds with a Coquina limestone on top. Still south of this a 

 section one-half mile east of Algodones shows heavy beds of 

 yellow sandy clay overlain by yellow clay containing casts of 

 fossils and many valves of Pecten. This was followed by 

 another bed of yellow clay and this by a series of calcareous 

 sands and silicious gravel 20 feet thick with numerous casts 

 of a Cardita-like shell and single valves of large oysters which 

 appear to have been transported. The same beds are also 

 found in the hill one mile north of Algodones and extending 

 two miles or more to the eastward. These Oligocene sands 

 and clays also form the body of the hills north of San Rafael, 

 on the Conchos, and the eastern flank of the Pomeranes. To 

 the north and east of this locality their extension is largely 

 hidden by the Reynosa covering. 



Neocene 



Coquina Limestone 



Overlying these fossiliferous sands and sandy clays of the 

 upper San Fernando, which seem to have a thickness of 300 

 feet or over, we find a bed of Coquina limestone, or possibly 

 a succession of such beds. Half a mile east of the bluflf near 

 San Fernando, the Coquina limestone was found overlying 

 the beds of the section as already given, and similar Coquina 

 is found near San Diego, capping a small hill and occupying 



