Review of liecenf Geological Literature. 07 
gradual descent from the general to the special. The author begins 
with cosmical geology, i. e., the relation of the earth to other members 
of the solar system, a section of geology which has usually been rele- 
gated rather to astronomy, but which the late Alexander Winchell, in 
America, and others, mainly of England, have brought forward as one 
of the legitimate fields for the geologist to traverse and exploit. 
Through geognosy the author then descends to a more special examina- 
tion of the chemical and physical forces that have produced the geo- 
logic changes which are embraced broadly under physical geography, 
and then enters upon an actual determination of the stratigraphic suc- 
cession, the sources of the various rock masses, their different posi- 
tions and relations. This eventuates in paleontological geology, involv- 
ing a study of successive organic forms, and hence in historical geology. 
These facts being set forth in sufficient detail, and with sufficient 
discussion of differing views, the last step is to apply the laws deduced 
to the explanation of the present immediate surface and contour of 
the earth — this branch being physiographical geology, involving the 
causes of the surface phenomena, such as ocean basins, plains, valleys 
and mountains. Thus, from the remote and general the author de- 
scends by an easy and even a graceful logical sequence to the present 
and special. It is a philosophical sequence of topics, without making 
any prominent pretense at such succession. 
The second characteristic is its familiarity with present American 
authorities, and its frequent citation of authors by copious foot-notes. 
The former characteristic adapts the work to a miscellaneous class of 
general students, making it a book that can be read, while the latter 
commends it to the working geologist and the enquiring and studious 
teacher. It is preeminently adapted to English-speaking geologists, 
and again especially to American geologists. 
The author inculcates his views, when he reveals them at all as his 
own, by a judicious selection of authorities. He is apparently not a 
strict uniformitarian, nor is he a catastrophist. He mentions several 
considerations which conspire to indicate that in the early part of the 
earth's history as an individual in the solar system, even within the 
time of sedimentary accumulation, geological forces were much more 
effective and intense than they are now; at the same time he allows 
that the surface phenomena produced, owing to the present greater 
rigidity of those parts most likely to present legible results of the same 
forces, are greater than in the earlier part of sedimentary geology. 
He presents briefly the data and the reasoning of geologists and of 
physicists for the age of the earth. He intimates that the physicists 
have probably overstated their case, in limiting the duration of geolog- 
ical time to fifteen or twenty million of years, and is inclined to con- 
sider the period of about 100 millions of years as none too long. This 
not only agrees approximately with the results originally announced 
by Lord Kelvin, in England, but also with results more lately reached 
by de Lapparent, in France, and Upham and Walcott, in America, as 
well as by Reade, in England. 
