1913] 



Louderbach : The Monterey Series 



185 



in the Sespe region it underlies the latter with the same attitude, 

 — that is, apparently conformably, but that relationship is subject 

 to doubt. 



At the least, the local representative of the Vaqueros as 

 redelimited to include the so-called "upper Sespe" shows a 

 sudden and permanent change in the type of sedimentation from 

 that of the "brownstone" or "red beds," so that even with a 

 conformable relation there is a natural line of demarcation be- 

 tween them, and a special name will probably always be desirable 

 for the red beds, even if they are included within the series above 

 or below them. 



This brownstone series is a rather local phenomenon. It 

 runs west a few miles into the Santa Barbara region, but as far 

 as known is not found to the north of the Santa Ynez river. 

 Its extent east and south is also rather limited. It appears to 

 be confined to a territory including southern Santa Barbara and 

 Ventura counties and possibly part of Los Angeles County. 

 Passing beyond the limits of this region the Vaqueros retains 

 its general features, but the Sespe has disappeared, and as far 

 as now known nothing just like it is found elsewhere in Cali- 

 fornia. 12 



These relationships would at least suggest that the Sespe 

 brownstone formation is not a member of the Vaqueros-Monterey 

 series, and may be separated from it by a time break or uncon- 

 formity. At the April, 1912, meeting of the Cordilleran Section 

 of the Geological Society of America. Mr. Robert Moran reported 

 the unconformable relationship of the Vaqueros and Sespe in 

 the restricted sense as delimited above, as seen in southern Ven- 

 tura County, and in the writer's opinion the mapping of these 

 groups and the relationships of the Vaqueros-Monterey volcanics 

 to the Sespe in the Semi region appear to offer good evidence to 

 support this view. 



No special reason has been put forward for attaching the 

 white sandstones below the brownstone formation to the Sespe 



!2 The writer has seen beds that suggest the Sespe type of deposition 

 on the hills to the west of the Carrizo plains, but their stratigraphic rela- 

 tionships were not determined. The reddish to purplish shales above the 

 fossiliferous Tejon sandstones in the Mt. Diablo range may be a corre- 

 sponding facies of deposition. 



