Review of Recent Geological Literature. 385 
It is, of course, difficult,, iu a revision of an old text-book, to amplify 
it equally, and bring it up to date in all directions without the substan- 
tial creation of a new work. One might wish that the author had taken 
the time to make such a new work. It is needed, in the light of recent 
great progress, and the antiquated condition of some of the views advo- 
cated by the text of this. Perhaps it is impossible for a single author 
to compass the whole science of modern geology without seriously com- 
promising and belittling some departments. Perhaps it is necessary 
that some such method shall be pursued as that recently adopted Ijy 
Eastman in respect to modern paleontology, i. e., assign the parts to 
specialists, with freedom to incorporate the latest, well authenticated, 
classification and the most advanced views. The text before us suffers 
materially in consequence of the non-comprehension of some of the im- 
portant fields of recent research in American geology. The magnificent 
results of the U. S. Geological survey, and of several of the state sur- 
veys, brought out mostly since the last edition of this text-book, are but 
slightly reflected from its pages, one might almost say entirely over- 
looked. This is particularly apparent in the treatment of the Archean 
and the lowest paleozoic. It is not necessary to specify. This makes 
the work less adapted to the northern states where the vigorous and 
advanced schools of geological science are mostly located, since these 
rocks are specially prominent in the northern parts of the United States 
and in Canada. 
The common view of the origin of anthracite by metamorphism of 
bituminous coal is given: the exceptions and modifications, and the in- 
adequacy of this view are pointed out, but nothing is said of Steven- 
son's theory of the origin of anthracite which was published several 
years ago, and which eliminates these difficulties. The author also 
repeats the old and insufficient notion of the old edition as to the origin 
of iron ore, making it a result of organic acids acting on the rocks that 
contained it in disseminated state. "Therefore we conclude that both 
now and always iron ore is, and has been, accumulated by organic 
agency." This is the sole cause mentioned. On the contrary, that 
several well authenticated sources of iron ore are admitted by most ge- 
ologists is very certain. In the lake Superior region are very extensive 
deposits of titanic magnetite embraced entirely in the gabbro, and they 
must have been genetically connected with the gabbro, which is of ig- 
neous origin. The decay of basic silicates, and the concentration of 
their iron in suitable basins is a well-known process of iron formation, 
much dwelt on by J. P. Kimball. 
The author writes interestingly and forcibly on many general geolog- 
ical topics. That is one of the excellencies of the volume. Its summa- 
ries are often terse and yet lucid: witness his definition of the Permian 
in America, p. 426, or the discussion oT the interior of the earth, pp. 
86-88, and, in general, the presentation of the phenomena and cause of 
the Glacial epoch. 
The ijhenomena of the Quaternary period, whose cause is presumed 
to have been fluctuations of level in the high latitude portions of North 
