Vol. 6] Baker: Cenosoic History of the Mohave Desert. 349 



20° to the south has been displaced by a transverse fault, with 

 a stratigraphic throw of fifty feet and a horizontal displacement 

 of 200 feet. A stereogram of this fault is shown in figure 3. 



Fig. 3. Stereogram of fault on south side of dome, west of Black 

 Canon. The stratigraphic throw is 50 feet, while the horizontal displace- 

 ment is 200 feet. 



ROSAMOND BEDS IN THE CALICO MOUNTAINS 



The first account of the geology of the Calico Mountains was 

 given by Lindgren, who includes in his paper a sketch map and 

 cross-section. 8 Lindgren recognized the salient features of the 

 geology, representing the base of the Rosamond Series as resting 

 on rhyolite, that the series was sedimentary and made up of 

 coarse granitic and rhyolitic materials a,t the north and of finer 

 sandstones, tuffs, and clays at the south, and that the beds in 

 the southern portion of the exposure had been very closely folded 

 and faulted into juxtaposition with a flow of hornblende ande- 

 site, while the more massive beds farther north had been tilted 

 but not strongly folded. Storms" confirmed Lindgren 's obser- 

 vations and appears to have been the first to advocate a lacus- 

 trine origin for the borax beds in the tuffs, sandstone, and clays. 

 Campbell, 10 in a reconnaissance report on the borax deposits of 

 Death Valley and Mohave Desert, has the following to say con- 

 cerning the Borate locality : 



The principal deposit of boron salts occurs at Borate, about 12 miles 

 north of Daggett, in the vicinity of the old Calico mining district. The 

 mineral found here is borate of lime, or colemanite, and it occurs as a 

 bedded deposit from 5 to 30 feet in thickness, interstratified in lake sedi- 



8 The silver mines of Calico, California, Trans. Am. Inst. Min. Engrs., 

 vol. 15, pp. 717-734, 1887. 



9 Report on San Bernardino County, 11th Ann. (1st Biennial) Rept. of 

 the State Mineralogist, Cal. State Min. Bur., pp. 337-369, 1893. 



10 U. S. Geol. Surv., Bull. no. 200, 1902. 



