386 THE JOURNAL OF GEOLOGY. 
range lies wholly in the state of California, except the high gran- 
ite spur lying just east of Lake Tahoe. Diller* has suggested, 
however, on geological grounds, that the range be limited on the 
north by the lavas of the Lassen Peak region, in the neighbor- 
hood of the North Fork of the Feather River, for to the north 
of this line there existed during Cretaceous time a great depres- 
sion, which late in the Tertiary was filled in by the lava flows of 
Lassen Peak, which Diller considers as geologically related to 
the Cascade Range. 
A little to the west of the Tejon Pass, according to Whitney,” 
‘““we pass at once from undisturbed Tertiary to strata of the same 
age, which are elevated at a high angle, and in so doing we leave 
the system of the Sierra and pass to that of the Coast Ranges.” 
In a previous paper the writer suggested that this line, separat- 
ing little disturbed and highly disturbed beds, probably repre- 
sents a line of faulting, the continuation of which further north 
is apparently followed by the San Joaquin and Sacramento Rivers. 
As is well known, the upper Cretaceous and Tertiary strata to 
the east of these rivers in the Sierra Nevada lie nearly horizontal, 
while to the west of it they are at nearly all points deformed. 
Adopting Diller’s restriction of the range at its north end, the 
Sierra Nevada may be considered as terminating on the north, a 
little to the north of the North Fork of the Feather River; on 
the east at the west edge of the Great Basin; on the south at 
the Mojave Desert; and on the west at the hypothetical line of 
faulting above indicated. The eastern part of the Tehachapi 
Mountains will thus fall in the Sierra Nevada system. The geo- 
logic map (Plate VII) shows the range as thus restricted, the 
broken lines on the east and south being the line separating 
the Sierra Nevada from the Great Basin and the Mojave Desert. 
That portion of this line between Owen and Mono Lakes, and 
the portion east of Lake Tahoe coincide with a probable line of 
faulting, along which the Sierra has been elevated or the Great 
™ Eighth Annual Report, U. S. Geol. Sury., p. 404 and Plate XLV. 
2 Geol. Cal., Vol. I., p. 167. 
3 American Geologist, Vol. XIII., p. 248. 
