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



In the South End McKittrick area the basal 100 feet of the 

 Tulare contains similar oil sands associated with fresh water 

 fossils. Several shallow wells have been drilled into these 

 sands, but production has been small and the oil heavy. This 

 oil unquestionably came up along the stratification planes of the 

 underlying beds and coming in contact with the porous sands of 

 the lower Tulare, migrated along them. 



Etchegoin : (Lower Pliocene) 



No definite separation has previously been made of the 

 Etchegoin in the McKittrick, Midway, and Sunset fields. 

 Several writers have suggested that it existed but no one has 

 definitely segregated its small areas scattered along the lower 

 foothills. It is without doubt the most important oil produc- 

 ing formation of the West Side fields, and for that reason it 

 should be clearly distinguished from all others. 



It is exposed as small areas of sands, oil sands, clays, light 

 marls, and marly shales along the lower foothills and is 

 usually overlapped at both ends by the Tulare. Only a few 

 clear cut contacts with the underlying shales can be found. 



The recognition of sediments of the Etchegoin in the South 

 McKittrick area was due to the discovery of a prolific bed of 

 fossils made of Pecten eldridgci, Echinarachnius gihbsi, and 

 Ostrea, species along the McKittrick Sunset Road. This bed 

 is traceable along its strike for a mile or more. It is best ex- 

 posed to the east of the county road in the N. E. ^4 of Sec. 

 28. The lower part of the Etchegoin at this locality is made 

 up of well-rounded hard quartzose and granitic pebbles along 

 with which are strata of gray and yellow firm to hard sands 

 with occasional layers of porous white, marly shales. The 

 latter might easily be mistaken for organic shales. The line 

 of pebbles at the base is persistent and can be followed with 

 a few breaks around the south end of this area and westward 

 again for several miles along the front of the McKittrick oil 

 field. 



Within the particular area treated in this report the Etche- 

 goin forms a very narrow belt, mostly of sandstone strata 

 from the N. E. ^ Sec. 29 diagonally across Sec. 28 and the 

 S. W. 54 Sec. 27. Around the point of the anticline in Sec. 



