16 The American Geologist. July, 189* 
also seems to the writer to be, in important portions, erro- 
neous. With acceptance of the review of the Glacial period 
as given by Kendall and Gray, there appears no warrant for 
their opinion that it was caused by a diminution, and ended 
by an increase, of the sun's heat. During the centuries of 
written history, and especially during the past century of 
critical investigations in terrestrial and solar physics, no vari- 
ations of this kind have been discovered. Such a cause of 
the glacial accumulations would have enveloped Alaska and 
Siberia with ice-sheets and their drift deposits. The anoma- 
lous geographic distribution of the drift forbids this hypoth- 
esis. Prof. H. A. Hazen, of the U. S. Weather Bureau, in a 
paper contributed to the Engineering Magazine for March, 
1898, shows that the climates of Palestine, Egypt, and China, 
have undergone no appreciable change during the past 3,000 
to 4,000 years. 
The fully proved land-ice origin of the general drift sheets 
in North America and Europe effectually opposes LindvalTs 
theory of the nature and causes of the Glacial period; and 
the remains of past life in the rock strata are discordant with 
his supposition concerning the torrid zone previous to the 
Quaternary era. 
If we should accept Tait's and Newcomb's estimate, that 
the existence of the sun since its contraction past the place 
and time of its shedding off the matter which now forms the 
earth and moon, has been no longer than about ten million 
years, we should surely require for the geologic record all the 
time possible under that hypothesis. Life might then be sup- 
posed to have begun on the earth when the sun was so large 
as Blandet and Falsan suggest : but more probably the sun is 
vastly older, as one to two hundred millions of years, so that 
the solar contraction and intensity of heat became nearly 
what they are now before the time of the oldest known fauna 
of the Cambrian rocks, which, to judge from its stage of de- 
velopment, was far from the beginning of life on our planet. 
The occurrence of many and distantly separated areas of 
late Carboniferous or Permian glaciation, marking the only 
time of wide prevalence of glacial conditions previous to the 
Pleistocene ice age, as reviewed by C. D. White in the Ameri- 
can Geologist (vol. in, pp. 299-330, May, 1889) and in 
