The Cause of the Glacial Epoch. — Reed. 1 1 1 
The planet Mars is cited as an illustration of a planet 
which has completely emerged from an Ice age and whose 
climate is entirely under solar control; while Jupiter is an 
example of a planet whose climate is under control of inter- 
nal heat. 
In an appendix, the author treats of the unglaciated area 
of the western United States and of the conditions which 
prevented that region from being invaded by ice. He 
claims that, at that time, the Columbian lava plain was still 
hot, and that the warm air and rain passing over and falling 
upon the lava plains made the Missouri river a warm river 
during the Ice age, so that it checked the advance of the 
glacier and made the unglaciated area the last resting place 
for Tertiary forms. 
The Ice age, then, is not to be regarded as a meteorologi- 
cal freak but as the logical outcome of the laws of climatic 
development. 
After speaking of the principal theories which have been 
advanced to account for the occurrence of an Ice age, the 
author gives a good criterion of the worth of any such 
theory — "An explanation which will admit of definite proof, 
and will satisfy all the conditions and will not require the 
distortion of known facts, by forcibly fitting them into ar- 
bitrary molds, will receive universal acceptance." 
In the presentation of this hypothesis, the author gen- 
erally employs good scientific logic. There is no grievous 
conflict between the laws of physics and the laws of mete- 
orology upon which his argument rests, yet the reader, in 
passing, cannot fail to notice that some of the theories arc 
contradicted by Nature's known facts. 
If the Palaeozoic had a uniformly tropical climate, (as 
this theory holds), how are we to account for the widespread 
evidences of glaciation occuring at the close of that era? 
In this connection, the liberty is taken to quote from a 
recent writer:* "Whatever may be the thought of the sup- 
posed signs of cold periods at other early periods, the evi- 
dences of glaciation in India, Australia and South Africa 
near the close of the Palaeozoic era are so abundant, so 
specific and so well attested that they cannot be ignored and 
*T.C. Chamberlain, Jour, of Geol. Vol. 7, No. 6. 
