396 The American Geologist. December, lsos. 
lected by Hansen from many observers in America and Europe, it cer- 
tainly seems to be well demonstrated that this period is about 7,000 to 
10,000 years. 
High uplifting of the land areas which were glaciated is shown to be 
the primary and chief element in the causes of the Ice age, partly b/ 
fehe prevailing cold and snowy climate normally due to the land elevation, 
and partly by the effects of diminution of the amount of carbon dioxide 
then held in the atmosphere on account of the considerably increased 
exposures of land surfaces and decrease of the sea areas before the 
Glacial period. During the same time of general continental uplifts, and 
because of them, volcanic action yielding carbon dioxide was probably 
somewhat diminished, tending, with the diminution through changed re- 
lations of the land and sea, to produce cooler climates over all the earth. 
Thus a variety of conditions dependent on the great epeirogenic uplifts 
concurred in causing glaciation. 
Conversely, it is seen that during the Champlain epoch, or closing 
stage of the Glacial period, not only the general depression of the lands 
beneath their ice burden, but also a concomitant increase of the carbon 
dioxide in the air, due to reversal of all the former means of its deple 
tion, caused rapid melting and retreat of the ice-sheets. 
With the able revision of this edition, it deserves a long continuance 
of the favor in which it has been held during the past quarter of a 
century. w. u. 
The Autobiography of Joseph Le Conte. Edited by William Dallam 
Armes. Pages 337 ; with portraits and views from photographs. 
New York: D. Appleton & Co., 1903. 
Within the last year of his life, this veteran geologist, student of 
Agassiz, South Carolinian through the Civil War, and later for more 
than thirty years professor in the University of California, prepared 1 
manuscript autobiography for his children, grandchildren, and great 
grandchildren, to whom from time to time, as his writing advanced, 
portions of it were read. It is from beginning to end a most interesting 
life history. 
In the final pages, summing up his life work, the following personal 
estimates are given : 
"In Geology, I believe some real substantial advance in science was 
made in my series of papers; (1) on the structure and origin of moun- 
tain ranges; (2) on the genesis of metalliferous veins; (3) especially 
in that on critical periods in the history of the earth ; (4) on the demon- 
stration of the Ozarkian, or, better, the Sierran epoch, as one of great 
importance in the history of the earth. I might mention several others 
that I believe are of prime importance, but I am willing to stand by 
these. 
"I look back with especial pleasure on my writings on evolution. .. . 
In my lectures in 1872 on Religion and Science, I might be called a re- 
luctant evolutionist. .. .In a few years, however, I was an evolutionist, 
thorough and enthusiastic. .. .It is, indeed, glad tidings of great joy 
which shall be to all peoples. Woe is me, if I preach not the Gospel. Lit 
