REVIEWS. 439 



its physical characters that the Lafayette formation has been investi- 

 gated and largely explained. 



The author of " The Lafayette Formation " has made one of the 

 most important recent contributions to geological science. Besides 

 his contribution to the geology of an enormous area, the principles 

 of geomorphy are emphasized, and the interpretation of the conti- 

 nental changes of the later Tertiary days are set forth in an original 

 manner, forming one of the most interesting chapters in dynamical 

 geology. 



The maps are particularly worthy of attention. The first repre- 

 sents the physiography of the coastal plain, and its relations both with 

 the higher land area and deeper oceanic depression. The next is a 

 colored map showing the distribution of the Lafayette formation and 

 the overlying Columbia. The third map shows the continental area 

 during the Lafayette subsidence ; it is both a topographical and hydro- 

 graphical chart of the physical features of land and sea when 250,000 

 square miles of the southeastern part of the continent was submerged. 

 It is of special interest. Then follows the topographical map of the 

 high continent during the post-Lafayette elevation, when the conti- 

 nental region was expanded by 100,000 miles or more in excess of 

 that of modern times. The last map shows the continental contraction 

 during the Columbia period — and a very strange looking map it is 

 with the land margin dissected by numerous estuaries, scores or 

 hundreds of miles in length, resulting from the submergence of the 

 great valleys of the south in_ connection with the tilting of the land 

 toward the South Carolina axis of oscillation. 



Although this work was commenced by others, yet the extension 

 and digestion of the whole belongs to the author, and it is a remark- 

 ably meritorious work. But in the study of geomorphy, and of the 

 most interesting continental changes, the work is almost entirely 

 original. The whole forms one of the most complete, yet peculiar, 

 chapters of American geology. This review is only sufficient to call 

 attention to a very suggestive report in which, hqwever, there are still 

 some questions left open. The author is to be congratulated on having 

 taken up such an important and interesting but little known subject, 

 and for working it out to such a degree of completion. 



J. W. Spencer. 



