REVIEWS 9/3 



mas, the Cambrian, the structure and affinities of trilobites, of Mesozoic 

 reptiles, and of Mesozoic and Tertiary mammals, and the causes of 

 glacial and other geological climates. Earthquakes are treated in a 

 relatively elaborate way, which is perhaps warranted by the popular 

 interest they awaken. They are, however, given more space than 

 rivers, which have incomparably greater geological and educational 

 importance. It would, we believe, have been better to bring the treat- 

 ment of rivers and of topographic evolution well up to date even at 

 the expense of a reduction of the space previously given to earth- 

 quakes, and to other less universal phenomena. The brief statement 

 of magmatic differentiation, the greater emphasis placed on the Cam- 

 brian, and the later results of research on the trilobites, reptiles and 

 mammals are all welcome additions. Much less, we fear, can be said 

 in commendation of the discussion of glacial phenomena. The 

 opening statement (p. 568) relative to the great oscillations of the 

 earth's crust, and especially the unqualified assertion that "the glacial 

 epoch is characterized by an upward movement of the crust in high- 

 latitude regions, until the continents in those regions stood 1000 to 

 3000 feet above their present height," appears to the reviewer to need 

 revision ; at least, the student and the general reader should be 

 informed that this once current doctrine has been cast aside by many 

 of the most experienced glacialists on both sides of the Atlantic. 

 That there was a very notable elevation in the Pliocene period is not 

 doubted, indeed, among its strongest proofs are the very phenomena 

 appealed to in proof of elevation in the glacial period. Unless the 

 modern science of geomorphy goes for naught, the elevation that 

 produced the fjords and the ragged borders of the northern coasts 

 took place very Inuch anterior to the glacial period. Concurrent with 

 this evidence there has been gathered within the last few years a great 

 mass of data which indicates that during much of' the glacial period 

 only a moderate — indeed, in part, a rather low — altitude prevailed. 

 A conservative author may well be pardoned for not accepting these 

 new doctrines, but scarcely for leaving students in total ignorance of 

 them. A specific error of much significance is the statement, follow- 

 ing Hilgard, that the Lafayette sands and gravels contain northern 

 bowlders, and their consequent reference to the glacial period. Crys- 

 talline pebbles, presumably of glacial origin, occur in the sands and 

 gravels of the Natchez formation, which bears some resemblance 

 to the Lafayette, because largely derived from it, and hence has 



