Reviews — Sharp's Rudiments of Geology. 377 



attributed." He finds in these phenomena an argument for their 

 explanation rather by sudden and excessively violent shocks at very 

 distant intervals than by minor and more frequent oscillatory move- 

 ments. We cannot in this brief notice enter on a criticism of this 

 argument, or we might, we think, show that it contains a fallacy. 

 We join, however, heartily in the concluding passage of this portion 

 of the address : " Of these forces it is as difficult for us to realize the 

 intensity as it is to fathom the immensity of space. These are among 

 the questions of the future." (p. 40.) 



Presuming, however, the earth to have arrived at present at a 

 state of comparative " quiescence," Mr. Prestwich suggests that the 

 glacial period through which the earth has recently passed, owing 

 to whatever cause, anticipated in some degree the ultimate refrigera- 

 tion of the globe through the radiation of heat into space ; and by 

 retarding this process has tended to produce that " period of stable 

 equilibrium" which now obtains, and "which now renders it so 

 fit and suitable for the habitation of civilized man ;" and thus 

 " impresses the author with the belief of great purpose and all- wise 

 design." (p. 48.) 



II. — Kudiments of Geology. By Samuel Shakp, F.S.A., F.G.S. 

 (Stanford, London, 1875.) 



THE object of this book is to give, in a condensed and useful form, 

 an abstract of the most noticeable points in geological research. 

 It is, in fact, rather a series of brief notes of lectures, than a treatise 

 on Geology, and its very size, for it runs into little more than a hun- 

 dred pages, precludes the possibility of the author's doing more than 

 indicating the salient facts and theories of the science. 



This has been satisfactorily attempted ; and the arrangement is 

 well adapted to the wants of students who seek for much information 

 in a small space. 



The First Part deals essentially with Definitions, a separate para- 

 graph being devoted to each ; these are both word-derivations, and, 

 in many instances, explanatory notes of the matter in hand ; and 

 are of considerable value. 



For example, paragraph 15, which relates to " the processes by 

 which sedimentary strata have been formed at the bottom of rivers, 

 lakes, estuaries, and seas," does not confine itself to a brief statement 

 that Denudation (marine, sub-aerial, or glacial) was the chief cause, 

 but proceeds to describe the process, and to give numerous examples 

 of the action of these several agents. 



There is, however, a tendency in some instances to popularize in- 

 formation and simplify terms in a hasty and inaccurate manner. 

 This may often lead to false impressions. Thus granite is spoken 

 of as " the original foundation and source of all rocks," which is 

 certainly open to question. Again, some of the derivations of tech- 

 nical words are careless ; for stratum is not a "covering " body, onto, are 

 not necessarily " existing" beings, meta is not " change," and, if the 



