Review of Recent Geological Literature. 51 
That theory supposes that the poles of the earth perform a rotary 
spiral motion "from southeast to northwest," each pole going round the 
earth and gradually approaching the position before held by the other 
but beginning again to return when it reaches within 30 degrees of that 
position. It requires much examination of the book to correctly ap- 
prehend the author's conception of this motion. One might suppose, as 
the reviewer did, that the direction of the axis of the earth might shift 
under this hypothesis, either with respect to the earth's mass, or w ith 
respect to the solar system, but that is not the idea entertained by tlic 
author. He adopts the idea that the pole is not necessarily the ex- 
tremity of the earth's axis, but a certain geographic point, and that this 
point in the earth s surface may wander from the extremity of the axis 
while the rotation and oblateness remain constant. In short the author's 
theory is that the surface shell of the earth rotates spirally on the inter- 
ior mass, occupying inconceivably long periods, and that this rotation 
gradually submerges lands and elevates the bed of the ocean. This is 
invoked to explain the changes of continents, the geographic shifting of 
faunal characters, the variations of climate and all the physical changes 
which geological history requires. 
It is wholly a speculative composition built on the same plan as 
much of the geological works of a hundred years ago. It has many quo- 
tations of curious and quaint notions of the ancients — a veritable reser- 
voir of scientific curios from the literature of the past, especially of such 
as discuss the general cosmos. x. h. w. 
Geology of old Hampshire Cou/ify, Massac/inselfs, lOiz/prisiiig 
Franklin, Hampshire and Hampden Counties. By B. K. Emersox. 
U. S. Geol. Survey, Mon. XXIX, 782 pp., pi. xxxv. Washington, 1898. 
Price $1.90. 
The geological map accompanying this monograph covers an area 
of approximately 1,700 miles extending in a north and south direction 
across the state of Massachusetts and embracing the valley of the 
Connecticut, largely underlaid by Triassic sandstones, together with 
a considerable area of crystalline uplands on either side. This por- 
tion of the valley is one of the classic grounds of American geology 
and the appearance of this report has been awaited with much in- 
terest. From the nature of the area covered, the report divides itself 
naturally into three parts, dealing respectively with the crystalline 
rocks, the Triassic sandstones and traps and the drift. 
The crystallines. The section relating to the crystallines is of im- 
portance in itself and because of its close connection at two points with 
the general problem of the older rocks of New England: for, (i) 
joining as it does the east side of the area reported on in Monograph 
XXIII*, it continues half way across New England the section of 
metamorphic Cambrian and Silurian rocks which had already been 
carried from the Hudson to beyond Hoosac mountain, and (2) the 
work will furnish a base whence the study of these older rocks may be 
carried into northern New England and Connecticut, since the rocks 
*Geology of the Green Mountains in Massachusetts, bv Pumpellv, 
Dale and VVolfT. Mon. XXIII, U. S. Geol. Survey. 
