754 CALIFORNIA ACADEMY OF SCIENCES. 



The ascent and descent to and from Sierra Laguna is 

 one of the most arduous in the Cape Region, especially 

 when pack-mules are to be brought along. 



Geological J^eatures. — Although no special attention 

 was given the geological structure of the Cape Region, 

 a few observations taken on the road may not be without 

 ♦ interest. The main sierra from El Chinche to Sierra La- 

 guna, and beyond it to Triumfo, consists of a granite up- 

 heaval, which almost everywhere shows signs of the 

 glacial period. This is especially evident on the east side. 

 Here, all along from San Jose to Rodeo, we meet with 

 enormous morains, which all run more or less parallel 

 from west to east. Especially are the morains prominent 

 between Miraflores and San Bartolo. At the lower end 

 of the canon of San Bartolo are large steep morains, 

 known as the Quebradas de San Bartolo, consisting of 

 enormous boulders heaped on the top of each other, 

 several hundred feet high. The coast mountains east of 

 San Jose River and from there on to La Paz in the norths 

 appear to consist chiefly of volcanic stratified red rocks. 

 East of San Jose, however, comprising a district from 

 near San Jose River and running east, we meet with hard, 

 crystalline nonfossiliferous lime formation. This forma- 

 tion gives to the country an entirely different aspect; the 

 mountains, instead of being rounded, have the form of 

 table-mountains, crowned by very, sharp, needle-like, 

 pyramids. How far this region extends northward I am 

 unable to say. 



I think there is every evidence that the whole of the 

 Cape Region is in a state of upheaval, and probably has 

 been so ever since the end of the glacial period. At Mag- 

 dalena settlements I found successive sea beaches several 

 hundred feet high, with the same shells as now living in 

 the ocean below, in very good state of preservation. 



