igo The American Geologist. March, 1904. 
REVIEW OF RECENT GEOLOGICAL 
LITERATURE. 
The Evolution of Earfh-Stnictnrc, with a Theory of Geomorphic Changes. 
T. Mellapd Reade. 40 plates. 342 pages. Longmans, Green and Co., 
London, New York and Bombay. 150,3. $7.00; by mail. $722. 
The author of this volume here presents not only some of his views 
of the cause of the features of the surface of the earth, some of which 
are well known through his earlier volume, "Origin of Mountain Rang- 
es," but also gives the details of experiments conducted by himself upon 
artificial plates of various kinds designed to show the effect of com- 
pression comparable to that exerted naturally in the rocks of the earth's 
crust. 
Mountain ranges are the result, according to Mr. Reade, of lateral 
compression due to cumulative recurrent expansion in regions of great 
sedimentary loading. But the continental areas are produced and main- 
tained by a different force. He shows clearly that the theory of isostasy 
will not account for the rise or depression of the continental plateaus. 
It is even more clear that the action of lateral thrust, which causes 
mountain ranges, does not maintain the continents in their position 
aibove the oceanic basins. The avithor's view is that the continents stand 
higher because of lower specific gravity than the crust below the oceans. 
This difference of specific gravity causes the lighter rocks to float, as it 
were, like a cork on water, but is not due to a difference of mineral 
composition. Mr. Reade argues that there is a sort of pulsation in the 
interior of the earth by reason of which the internal heat rises towards 
the surface and recedes again at long and irregular intervals, sometimes 
heating the crust say of the North American continent, causing it to 
rise, and again allowing it to cool and contract, and hence to be slightly 
depressed again. The loci of heated areas shift from place to place, but 
they always cause an expansion and hence an elevation. It is hence 
still a species of isostasy to which Mr. Reade appeals, but not one that is 
affected by sedimentary loading. 
Per contra the oceanic "deeps' ' are due to greater cold and hence to 
greater density. They therefore sink under the same law that causes 
the continents to rise. If the bottoms of the ocean be affected by any 
of these shifting heat-loci they expand, rise, thrust the oceans upon the 
land and perhaps inaugurate new geological epochs or sj-stems. Their 
shrinkage again causes the uncovering of the lands and their more rapid 
denudation. 
Mr. Reade's conclusions are the result of long study, and of great 
familiarity with American and English geological literature, and are 
worthy of the most careful attention. There is, however, an obstacle in 
the application of the theory, at the outset, which Mr. Reade does not 
consider. He speaks of the downward increase of heat in tlie earth's 
