206 The American Geologist. March, 1892 
temporary with, the greatest extension of the glaciers of the Glacial epoch. 
The author believes that the great weight of the accumulated ice caused 
a sinking of the earth’s crust, and that such sinking had its complement 
in the contemporary rising of other areas nearly contiguous, or perhaps 
more remote, causing fractures, faults, volcanoes, laccolites and elevated 
domes.. 
Mr. Upham also traces a relation between the great ancient lakes. 
(Bonneville and Lahontan) and the glacial period. The first flooded 
stage he considers was contemporary with the second glacial epoch, and 
the second high stage was due to a third epoch of glaciation in the 
northern part of the Cordilleran region. 
These orogenic movements, so called by Gilbert and White, are to be 
distinguished from the epirogenic, which consist of slower and grander 
elevations of large continental areas. The unequal denudations of these 
larger areas result in the carving out of mountains which constitute Mr. 
Upham’s sixth class—‘‘eroded mountain ranges.” Such are the Crazy 
mountains in Montana, and the Highwood mountains, twenty-five miles 
east of Great Falls. Turtle mountain, Pembina-mountain, Riding, Duck 
and Porcupine hills in North Dakota, illustrate this structure. This. 
epirogenic movement also took place at the close of the Cretaceous, or 
early in the Eocene. Indeed, the “Tertiary era seems to have been ter- 
minated, and the Quaternary ushered in, by a new epirogenic differen- 
tial uplifting of this continent, causing the accumulation of the ice-sheet 
of the first Glacial epoch.” * * * “There have been two epochs pre- 
eminently distinguished by extensive mountain plication, one occurring 
at the close of the Paleozoic era, and another progressing through the 
Tertiary and culminating at the beginning of the Quaternary era, intro- 
ducing the ice age.” * * * “With the culminations of both of these 
great epochs of mountain building, so widely separated by the Mesozoic 
and Tertiary eras, glaciation has been remarkably associated, and indeed 
the ice accumulation appears to have been caused by the epirogenic and. 
orogenic uplifts of continental plateaus and mountain ranges.” 
Within the scope of the paper the author has gathered most of the 
collateral American data derived from a study of mountains, which go to: 
illustrate, if not to demonstrate, his theory of the cause of the glacial 
epoch, viz., continental elevation. 
General Account of the Fresh-water Morasses of the United States, with a 
description of the Dismal Swamp District of Virginia and North Varolina.. 
By NATHANIEL SOUTHGATE SHALER., pp. 255-339; with plates vi-xix, and 
37 figures in the text. (Accompanying the Tenth Annual Report of the 
Director of the U.S, Geol. Survey.) ; 
The swamp lands capable of drainage and use for agriculture in the 
United States, east of the Cordilleran mountain belt, are estimated to- 
comprise somewhat more than 100,000 square miles. Professor Shaler 
states that fully one-fifth of the most fertile fields in Great Britain and 
Ireland, also large tracts in northern Germany and in the valley of the 
Po, have been won in such bog districts; and he believes that the aggre- 
