MINERALOGICAL GEOLOGY 
409 
At Lang, north of Los Angeles, the borate bed stands on edge, 
and in view of the circumstances that two thick beds of basalt are 
associated a peculiar vein-like aspect is easily imagined. At Ven¬ 
tura the strata are likewise so steeply inclined that the impression 
of a normal vein formation at once presents itself. Calico shafts 
are nearly vertical. In the Daggett mine-shaft which is on the 
ore-bed the latter hades ten degrees, while the basset edges of the 
vertically disposed beds are visible for many square miles over the 
plain about. 
It is doubtless contact only with these occurrences that gave 
first outline to the vein hypothesis of colemanite formation. But 
when wider observation is made, and the Death Valley, White 
Basin and Callville Wash deposits are examined the fancied vein 
resemblance soon vanishes. It is at once perceived that the borate 
beds are integral parts of the normal sequence of sediments. Had 
the last mentioned localities been inspected first it is doubtful 
whether the vein hypothesis would ever have seen the light of day. 
In fact Gale, who originated the vein theory, and who most 
strongly advocated it after his study of the Ventura and Lang 
deposits, makes no mention of such interpretation when he later 
visited them and described the Callville Wash localities. 
Another mistaken notion is urged in support of the vein theory. 
Associated with the borate beds which the author mentioned 
studied are thick plates of olivine basalt that lie parallel to the 
bed. As stated elsewhere instead of these eruptive masses being 
intrusive sheets as might be easily inferred, they are really old 
surface flows, as is conclusively proven by their rough upper 
surfaces and their vesicular character. Possibility of boracic 
acid emanating from them to replace the calcium of limestones is 
virtually nil. 
To be sure, at Lang and Ventura the surface weathering of the 
strata has gone on so far as to obscure satisfactory observation. 
But at Daggett, the even surface of the desert is swept clean by 
the winds and the irregular edges of the strata stand out as sharply 
as the deckle leaves of a book. If hasty inspections at Lang, 
Ventura and Calico leave first impressions that the colemanite de¬ 
posits are veins, cursory visit to Daggett, White Basin and Call¬ 
ville Wash at once dispels the illusion, and leaves no uncertainty 
concerning the sedimentary nature of the borate beds. Keyes. 
