Review of Recent Geological Literature. 205 
J 
Prospect (Nevada. ) 
Cottonwood (Utah.) 
Castle Mt. (Brit. Col.) 
Braintree \ Stissing (N. Y.) 
ee ) St. John - Corsa (Ala. ) 
‘(Avalon ( Mt. Stephen (Brit. Col.) 
{ Granular Quartz (N. Y and Yt.) 
Chilhowee (Tenn.) 
oes aae ue 
. Georgia acentia (Newfoundland. ) 
ee 4 Bee Sand- + Hanford (N. B.) 
: Rock | Attleborough (Mass.) 
The base of the Cambrian is drawn at the lower limit of the Oleaellus 
fauna. The summit of the group while placed at the upper limit of the 
Dikelocephalus fauna is in the Nevada district drawn arbitrarily, for the 
genera Asaphus, Dikelocephalus and Ptychoparia occur there on the same 
surface of rock. “It is not, however, by the specific break in the fauna 
that the two groups are separated; it is the general facies of the fauna 
referred to the Cambrian and that referred to the Silurian” (p. 363). 
Three maps accompany the bulletin. Une of these shows the outcrop 
of Cambrian rocks in the various provinces into which the country has 
been divided. A second shows by vertical sections the sedimentation at 
different points, and on a theoretical section the vertical contour of the 
continent at the end of Cambrian time, while the third is a hypothet- 
ical map of North America at the beginning of Lower Cambrian time. 
Many subjects are treated which cannot be alluded to here, and the bul- 
letin is full of information for those desirous of a better acquaintance 
with the rocks of which it treats and the pioblems connected with them 
A Classification of Mountain Ranges According to their Structure, Origin 
and Age. WARREN UrHaAmM. (Appalachia, Vol. vi, No. 3.) 
This consists of a review of the mountain systems of North America, 
with incidental mention of some others. Its evident purpose is to make 
clear the relation in time, and inferentially in cause and effect, between 
mountain elevations in the later Tertiary and early Quaternary time, and 
the Glacial epoch. This central idea finds its illustration in the mountain 
ranges of the western portion of North America. The “arched mount- 
ains” illustrated by theUinta range of northeastern Utah, dating from 
early or middle Tertiary, and by the Junction and Yampa mouutains, 
dating from the same time; the “domed mountains,” viz: the laccolitic 
Henry mceuntains in southern Utah, rising about the middle of the 
Eocene; the “tilted mountain” ranges, such as the Wahsatch and the 
Sierra Nevada which were formed io early Quaternary time, and the 
later smaller tilted ranges of the “great basin’—blocks of the earth’s 
crust raised bodily above the surrounding areas by abrupt fractures that 
penetrated deeply through the strata and then settled unequally, so as to 
assume a “tilted” position;—and many “erupted mountain ranges,” or 
volcanic cones and ridges formed by ejected lavas, bombs and ash, per- 
fectly illustrated by the Cascade range which crosses Oregon and Wash- 
ington, dating from late Tertiary and early Quaternary,—all these, which 
constitute some of the most unique and remarkable mountain ranges of 
the United States, are shown to have been produced just prior to, or con- 
