184 CALIFORNIA ACADEMY OF SCIENCES [Proc. 4th Ser. 



following fossils : Venericardia planicosta, V olutilithes pe- 

 trosa, Pseudoluva vetusta, Natica recurva, Harpa, sp., Pecten, 

 sp., etc. At the top of the hill are the Fayette sands with 

 Ostrea contracta. Southwest of Borregas the road passes 

 hills of reddish and purplish sandstone and yellowish sandy 

 clays which are also red in places. These beds have a north- 

 east dip and are visible until the San Domingo Ranch is 

 reached, 6 miles west of Borregas. Beyond this the coun- 

 try is level with no exposures for several miles until we find 

 a hill which shows the purple sands of the Yegua underlain 

 by the gray and yellow sandy clays of the Marine. Near La 

 Laja, which is on the railway near the Salinas River, the 

 Yegua occurs as heavy bedded gray, bluish gray, and red 

 sandstone with blue, brownish yellow and red clay shales, 

 followed by thinly stratified gray clays and sandstones. The 

 only fossils found were fragments of oysters. Half a mile 

 west of La Ciga, a small hill showing Marine strata at its 

 base seems to be capped with Yegua, a few fossils, including 

 Natica recurva, indicating that age. East of La Ciga the 

 chocolate sandstones and clays with cannon-ball concretions 

 are exposed in a low ridge for several miles. The Yegua con- 

 tinues to the Loma ford on the San Juan River, two or three 

 miles west of China. On the Conchos River, one mile east 

 of Angeles, where a large creek enters the river from the 

 south, there is a bluff some 75 feet in height with 25 feet 

 of purple lignitic shale at base, capped by yellow clays with 

 shaly sandstones and beds with nodules of carbonate iron 

 weathering red. This is typical Yegua. The latest beds of 

 Yegua seen were east of Sonada, where there are exposures 

 of blue and yellowish clays with gypsum, interbedded with 

 beds of sandstone four inches to two feet in thickness. Beds 

 of brown clays in a hill one mile west of Mendez mark the 

 top of its development here. No fossils were found here, 

 but its lithologic character and stratigraphic position warrant 

 the reference. 



Fayette 



The Fayette, like the Carrizo, is predominantly sandy. 



Like the Carrizo also, the Fayette, at times, overlaps the 



lower substages of the Eocene. Its exposure on the Rio 



Grande is fully equal to that of the Marine, stretching from 



