322 The American Geologist. November, 1902 
In other words, that kaohnization is comparable with ser- 
pentinization and similar changes such as are commonly- 
grouped under the head of hydro-metamorphism. This is, 
perhaps, the most striking of the conclusions arrived at in the 
paper under consideration. 
Unfortunately, the author does not give us satisfactory 
evidence of the correctness of many of his assertions, and one 
can but feel that many of his statements are based upon the 
literature rather than actual experiment and observation. 
JNIoreover, the Hst of quoted authorities, however large, is not 
cjuite satisfactory to the American reader. Thus, Dr. Ries, 
of Cornell, who is undoubtedly our best authority, is wholly 
ignored. It may be well, on this account, to call attention to 
the fact that Dr. Ries, in a paper read at the Detroit meeting 
of the American Ceramic Society in 1900, discusses the pos- 
sible origin of kaolin through fluoric vapors, instancing the 
work of Mr. Collins (Min. Mag., 1887), and stating it to be 
his opinion that the kaolins of Cornwall were undoubtedly of 
deepseated origin and possibly, also, those of Zettlitz in Bo- 
hemia. He affirmed, however, that there were as yet no 
known similar occurrences in America, all of the beds thus far 
exploited being due to surface weathering. To this view he 
still holds, as does also the present writer. 
More observations are, of course, necessary to establish 
this non-occurrence of deepseated kaolins beyond question,, 
but it will be only necessary to call attention to the fact that, 
almost Avithout exception, our residual kaolins, of sufficient 
extent to be of commercial importance, occur south of the 
glaciated areas, to throw a very substantial doubt upon the 
advisability of accepting ]\Ir. Rosler's conclusions in their 
entiretv. g. p. m. 
REVIEW OF RECENT GEOLOGICAL 
LITERATURE. 
United States Geological Survey, Twenty-Hrst Annual Report to the 
Secretary of the Interior, 1899-1900. Charles D. Walcott, 
Director. Part IV. Hydrography. F. H. Newell, Chief of Division. 
Pages 768, with 156 plates, and 329 figures in the text. Washington, 
1901. 
The first paper in this vokime is F. H. Newell's "Report of 
Progress of Stream Measurements for the Calendar Year 1899," in 
