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



low range or ridge divided in part by a narrow valley. This 

 ridge has a course of S. 60 degrees E. and in a general way 

 has its continuation in the Buena Vista Hills. Its highest 

 points rise to elevations in the neighborhood of fifteen hun- 

 dred feet above sea level and a thousand feet above the floor 

 of the San Joaquin Valley. The narrow valley, referred to 

 above, has an elevation of from 1300 to 1350 feet and is the 

 result of the erosion of much shattered shales and sands along 

 the apex of a sharp and faulted anticline. Here, as well as 

 along the whole belt of the West Side Oil Fields, the dissec- 

 tion of old and recent valley floors, stream flood-plains, terraces, 

 and fans is indicative of a general uplift of the region. East- 

 ward through the hills three steep-sided gulches lead out from 

 the small valley, in which are located some sulphur springs, 

 sometimes called Steamboat Springs. Along the sides of these 

 gulches there are more or less well preserved stream terraces 

 and flood-plains marking the once higher levels of the 

 streams. At one locality in Sec. 28 horizontal and cross 

 bedded oil stained detritus and brea form a prominent terrace 

 feature. Similar oil-stained deposits are found throughout 

 the entire length of the gulches and have frequently been 

 mistaken for live oil sands in places. 



GEOLOGIC FORMATIONS 



General Statements: Three and possibly four formations 

 besides the stream and valley alluviums are recognized within 

 this small area and afford a comprehensive example of the 

 formational relationships that exist in the McKittrick, Mid- 

 way and Sunset Fields. On both sides of a sharply folded 

 and locally faulted anticline there is exposed below the allu- 

 viums : 



( 1 ) Pliocene, Tulare fossiliferous, fresh water beds from 



1250 to 1800 feet in thickness ; 



(2) Lower Pliocene, Etchegoin fossiliferous marine sands, 



clays and marls 200 feet, or more; 



(3) Light colored organic shales with sandstone and cal- 



careous layers and lenses. These shales may be either 

 Santa Margarita or Monterey or both. Their posi- 



