76 Staten Island Association of Arts and Sciences 



Gratacap's Geology of the City of New York^ 



This is an elaboration of the author's two previous works on the 

 same subject, issued, respectively, in 1901 and 1904, and two sep- 

 arate papers, entitled, respectively. Evidences of Glacial Action in 

 and around Greater New York, published in New York Teachers' 

 Monographs 1:92-107. 1898, and The Ice Age, Pop. Sci. 

 Monthly 12:319-327. 1878. Reviews of two of these publica- 

 tions may be found in our Proceedings for Oct. 15, 1904, and 

 Oct. 8, 1898, under Literature Relating to Staten Island. 



In a work which contains so much that is interesting and valu- 

 able it is not a pleasant task to begin a review with what may 

 appear to be a mere criticism of the author's peculiarities of style; 

 but it is impossible to ignore certain features of terminology and 

 nomenclature in the Introduction which must necessarily be con- 

 fusing to the mind of the average reader, who can not be expected 

 to be well versed in such matters. 



For example, the author says '' Geologic Time has been 

 separated by American geologists into a number of subordinate 

 time groups. . . . The chart of geologic time, prepared and recog- 

 nised by American geologists, foUozvs (the italics are the re- 

 viewer's). 



An analysis of this so called chart shows such an extraordinary 

 mixture of terminology that it is difficult to imagine who the 

 geologists were that prepared it and what geologists would recog- 

 nize it. The primary divisions of the pre-Mesozoic and post- 

 Mesozoic time groups are designated "eras" (Laurentian Era, 

 Upper Silurian Era, Tertiary Era, etc.), but the coordinate divi- 

 sions of Mesozoic Time are called "periods" (Triassic Period, 

 Cretaceous Period, etc.); and this peculiar inconsistency is fur- 

 ther exemplified by the subdivision of the Upper Silurian " Era " 

 into the Niagara, Onondaga, and Lower Helderberg " Periods " ! 

 It would be interesting to learn how any similar coordinate sub- 



^ Geology | of the | City of New York | with numerous illustrations 

 and maps | by ] L. P. Gratacap, A.M. | American Museum of Natural 

 History | Third Edition, Enlarged | New York | Henry Holt and Com- 

 pany I 1909 I . 8""°, cloth, x-l-232 pp., with 65 figures and 4 maps. 



