202 



University of California Publications in Geology [Vol. 10 



beds in this part of the district are excellent. In some places a very 

 sudden change was found from a fine sandy shale below to local pockets 

 of conglomerate above the contact. At some localities the beds above 

 contain such an abundance of shale fragments that it is in places 

 difficult to distinguish the exact line of demarcation. The beds below 

 could in some instances be traced to a point at which they are cut off 

 at the contact or overlapped by the beds above. At one locality car- 

 bonaceous material was found with what apparently was the soil of 

 the old land surface. No measurable discordance in dip or strike could 

 be discovered. 



RELATION TO THE TULARE 



It is the writer's opinion that in the Coalinga and adjoining areas 

 tlie Etchegoin is conformable with the Tulare, and that the two were 

 laid down in a period of practically continuous deposition. Struc- 

 turally there appears to be no break, sedimentation having continued 

 without interruption from the Etchegoin into the Tulare. The only 

 recorded exception to this is reported in the Priest Valley region by 

 Pack and English,- who state that "in at least part of the Priest 

 Valley region the Tulare lies unconformably upon the upper Miocene 

 | Etchegoin] formation just described." This relationship is appar- 

 ently only local, however, as in the same publication' 21 it is stated 

 that "there is no sharp change in lithology between the upper 

 Miocene [Etchegoin] and the Tulare, and the line of contact has been 

 drawn at the base of the beds which contain abundant pebbles of 

 diatomaceous shale This gradual change in lithology and the lack 

 of any structural evidence of interrupted sedimentation suggest that 

 the formations are conformable here." Again the same writers 22 

 state : ' ' The line between the upper Miocene and the Tulare forma- 

 tion (Pliocene) is only a little more definite and has been drawn at 

 the base of the beds which contain abundant pebbles of diatomaceous 

 shale." In the McKittrick district 23 some distance south of the 

 Coalinga area, however, the Tulare rests on the Etchegoin with angular 

 unconformity. 



The deposits of the uppermost Etchegoin were laid down under 

 very shallow water on land conditions, as shown by the gypsiferous 



20 U. S. Geol. Surv. Bull. 581D, p. 134, 1914. 

 =i Ibid., p. 135. 

 -- Ibid., p. 133. 



23 Gester, G. C, Oral communication. 



