GEOLOGY OF CARRIZO MOUNTAIN, CALIFORNIA 355 



unconformity between the conglomerates and the clays. It is probable that this 

 interval is slight, but there are no data at hand for estimating it. 



Nos. 164 and 166 are from Alverson Canyon and the head of Garnet Canyon 

 on the south and north slopes respectively of Carrizo Mountain. The horizons 

 are identical, being in each case the sandstones which form the upper part of 

 the arenaceous series at the base of the Miocene. These are the most conspicuous 

 fossil localities in the region. The shells or their casts have weathered out and 

 strew the slopes in great profusion. Corals, echinoids, ostrea, pectens, strombus, 

 and malea are everywhere. The matrix, however, is coarse, and only large and 

 robust types are well preserved. The locality has been noted by prospectors 

 generally, because the occurrences are so conspicuous. 



No. 167. This collection consists of corals almost entirely. The fossil reef 

 is near the head of Barrett Canyon and lies directly upon the igneous rocks 

 which served as a basement for Miocene sedimentation at this point What- 

 ever later beds may have originally covered it have been stripped away, so 

 that the old reef is now isolated. There can be little doubt,- however, that its 

 position is at the base of the Miocene series and substantially equivalent to that 

 of Nos. 164 and 166. 



