Notices respecting Ne^ Books. 4*7 



earth, as well as that of springs, of seas and lakes, and of the atmo- 

 sphere ; and after noticing the various forms of valleys, and the obvious 

 changes now produced on the surface of our planet, he proceeds to a 

 classification of rocks, differing but little from that published by him 

 some months since in this Journal*. In a tabular form he shows its re- 

 lations to the improved Wernerian classification, and to the classifica- 

 tions of Conybeare, Omalius d'Halloy, and Brongniart. This classifi- 

 cation, which exhibits the rocks in the descending order, forms the base 

 on which the arrangement of the remaining part of the volume is found- 

 ed, and is chiefly characterized by the division of rocks into Stratified 

 andUnstratified; the former being divided into Fossiliferous, or those 

 which contain organic remains ; and Non-fossiliferous, or those in 

 which no animal or vegetable exuviae have ever yet been detected. 

 The fossiliferous deposits are subdivided into groups, the first of which 

 is termed Modern ; and under this head the author has treated of the 

 various causes which produce alterations on the actual surface of the 

 globe. We here find an account of the degradation of land, the de- 

 livery of detritus into the sea, the action of the sea on coasts, shingle 

 beaches, sandy beaches, tides, currents, the transporting powers of 

 tides and currents, active volcanos, extinct volcanos, mineral volcanic 

 products, earthquakes, gaseous exhalations, deposits from springs, 

 coral reefs and islands, submarine forests, raised beaches and masses 

 of shells, and finally a notice of the organic remains that may be en- 

 tombed in deposits now in process of formation. 



In treating on the above subjects the author appears desirous of 

 stating fairly the amount of that change which may be produced on 

 the surface of our planet by the causes usually termed actual; so that 

 when the phaenomena of a more ancient date are presented to the 

 attention of the reader, he might be enabled to institute a comparison 

 between the effects which we daily witness and those which have been 

 produced at more remote periods in the history of the world. 



We subjoin a few extracts to show the author's mode of treating 

 his subject, as far as can be done without the aid of the numerous 

 illustrative sections contained in this volume. — Speaking of the often 

 supposed case of the bursting of a lake, and the consequent deluge 

 that it has been imagined such a catastrophe would produce, he ob- 

 serves : 



" The waters of a lake can only be suddenly let out and produce a 

 debacle when the hard barrier separating it from the land at a lower 

 level presents a perpendicular face to the whole depth of the lake, 

 which, even then, must be suddenly thrown down in its whole height 

 to produce the eflect required. Such rocky barriers must be ex- 

 ceedingly rare ; and it must be still more rare that where they existed 

 they were not cut down, to a certain extent, by degrees. The common 

 character of lakes, as respects the inclination from their bottoms to the 

 discharging outlet, varies materially ; but in general the slope is very 

 gradual, particularly in lakes of considerable magnitude." 



A diagram illustrates the manner in which the lake Erie would be 



• Phil. Mag. and Annals, N.S. vol. vi. p. 440. 



drained 



