316 The American (ieohxjht . Ndvcmbcr, in95 
warm inariue current, brought again an arctic climate, the melting of 
the thick sheets of hind ice, protected by their superglacial drift, nearly 
ceased: and the mammoth and rhinoceros perished with cold and hun- 
ger, although these species had endured in migratory herds the more 
severe Glacial period, which there apjjarently was characterized by the 
accumulation of numerous local ice-sheets, occupying hundreds or 
thousands of square miles. Instead of merely ordinary winter storms 
and deep snowdrifts, to which Mr. Charles Davidson has attributed the 
extinction of the mammoth and the origin of the underground ice (Q. J. 
G. S., vol. 50, pp. 172-486, Aug., 1894), very important secular climatic 
changes, with epeirogenic movements, seem to have occurred in a series 
approximately parallel with those of the Glacial and Recent periods on 
the opposite sides of the North Atlantic ocean. w. r. 
FnrtJier Obserrations upon the Occurrence of DicDiionds hi Meteorites. 
By O. W. Huntington. (Proceedings, Am. Acad, of Arts and Sciences, 
new series, vol. xxi, 1894, pp. 204-211, with two plates.) The investiga- 
tion here noted was made with fragments of the Canon Diablo or Coon 
Butte meteoric iron, which was first described by Dr. A. E. Foote in 
the Proceedings of the American Association for 1891 (vol. xl, pp. 279- 
283), and to which also attention has been directed, with carefvil instru- 
mental surveys, Vjy Mr. G. K. Gilbert, as reported in the Am. Geologist 
(vol. XIII, p. 115, Feb., 1894.) Many pounds of this iron were dissolved 
by the author, who thus obtained from it enough diamond dvist to use 
at the Cokniibian Exposition for cutting and polishing rough diamonds. 
Only a few perfect crystals were found, these being of minute size, as 
about a hundredth of an inch in diameter. These observations seem 
well accordant with the theory of the late Prof. H. Carvill Lewis con- 
cerning the origin of diamonds, and he had actually predicted in 1886 
that diamonds would be discovered in meteorites. w. u. 
The Eroaive Action, of Ice. By G. E. Culvek. (Trans., Wisconsin 
Acad, of Sciences, Arts, and Letters, vol. x, pp. 339-366, April, 1895.) 
The opinions of many Eurojiean and American geologists are here re- 
viewed, and the author records his own observations of striated boulder 
pavements, where deposits of till have suffered glacial erosion near Big- 
Stone City, South Dakota, and on the Big fork of Rainy river in north- 
ern Minnesota. He concludes that the efficiency of ice to excavate rock 
basins has been greatly overestimated. Indeed he thinks that after 
the many years of discussion of this question, " not a single case of a 
lake basin which can be proven to have been made by ice action has 
been discovered." w. u. 
The Duration of Niagara Falls and the History of the Great Lakes. 
By J. W. Spencer. (Pages 126, with five plates and 27 figures in the 
text, forming the second part of the Eleventh Annual Report of the 
Commissioners of the State Reservation at Niagara, for the year 1894, 
Albany, 1895; also published, at the price of $1, in the Humboldt Li- 
brary series.) Nine papers relating to the Laurentian lakes and Niag- 
ara falls, published by Prof. Spencer within the past six years in the 
