GEOLOGY OF BAJA CALIFORNIA. 179 



DETAILED GEOLOGY. 



Post-Pliocene Strata. — Although, these deposits do not 

 form a prominent and conspicuous part of the topography, 

 they may be found in several places along the shore of Todos 

 Santos Bay. The numerous oscillations of the shore line 

 during post-pliocene time are equally plain in Lower Cali- 

 fornia as along the coast north of it. According to Prof. 

 Gabb these strata cover the mesa sandstones for hundreds 

 of miles to the south up to an elevation of 500 to 600 feet 

 above the sea, and consist of loose sands with shells, calca- 

 reous marls, etc. At Todos Santos Bay the deposits are not 

 extensive, but in places the old shore lines, indicating sev- 

 eral pauses in the movement, may be observed. At Ense- 

 nada there are no preserved strata, but the low mesa at San 

 Carlos belongs to this division. In the low hills skirting the 

 Sausal Valley remains of these strata occur resting on porphy- 

 ritic rocks. There are white, loose sandstones with remains of 

 shells; further up, one mile north of Sausal, a cliff about thirty 

 feet high shows a succession of sandstones and yellow clay 

 with coaly vegetable remains. On such seams the report of 

 the occurrence of coal beds between Todos Santos and San 

 Diego appears to be founded. Better than at any other 

 point the ancient shore lines are shown on Punta Banda, as 

 often well marked wave-built terraces. Two such shore 

 lines are plainly seen running along the promontory, but 

 on closer investigation, at least four distinct ones may be 

 found. The lowest and plainest about 40 feet above the 

 sea; above that another, not so distinct, at 180 feet; further 

 up, indistinct remains of beaches, at 470 and 600 feet. The 

 accumulations along the lowest beach line consist of sands 

 and gravel of porphyritic rocks, together with numerous 

 fragments of shells. 



Tertiary Strata. — These seem to be entirely absent, or 

 have at least not yet been found along the upper coast of 

 Lower California, an absence made more conspicuous by 



