610 
action are seemingly very incomplete in that 
no mention is made of the formation of 
shore-bars, spits, hooks, ete. It seems likely 
that the scalloped beaches described by Jeffer- 
son (Journal of Geology, Chicago, VII., 1899), 
might have light thrown on their origin by 
proper experimentation. 
“Glacial geology offers an extended field for 
experiments, and in this connection our author 
proceeds to imitate the formation of crevasses, 
employing stearin placed on a band of rubber. 
Tension is applied and crevasses are formed. 
To demonstrate glacial erosion by the striation 
of rock fragments, the simple friction experi- 
ment of Daubrée and others is repeated. It 
should be said that this experiment does not 
offer a very close analogy to the conditions in 
a glacier on account of the ‘plasticity’ of ice. 
But it is in regard to recurrent occupation of a 
field by glaciers that M. Stanislas Meunier 
makes his most novel suggestion. His propo- 
sition may be given in nearly his own words: 
“Given a glacier, and everything else remain- 
ing in equilibrium, it tends to diminish in spite 
of seasonable changes, by reason of the progres- 
sive lowering of its basin of supply [because] 
the materials which it transports in such great 
quantities along with the water which is asso- 
ciated with it, reduce the relief of the ground. 
It then recedes, and behind its abandoned 
frontal moraine vegetation is established. But, 
comparable at all points with rivers, it gnaws 
back progressively at its head, and it is possi- 
ble for this recession to reach the point by de- 
stroying the rocky aréte which separates its 
basin from that of a neighboring glacier, where 
it is permitted to divert this glacier to its own 
basin. Thereupon an increase of substance 
ought to provoke a return to the dimensions 
formerly held, and from that time the products 
of the fossilization of the plants established 
upon the first glacial terrane will be covered 
with a second morainal extension.’’ 
It is our author’s view that this phenomenon 
of capture of glaciers by being reciprocal and 
recurrent, accounts for the so-called successive 
glacial periods in the Pleistocene. He neces- 
sarily attempts to refute the theory that these 
epochs of glaciation and deglaciation are ‘ gen- 
eral and simultaneous.’ While the oscillations 
SCIENCE. 
[N. S. Von. X. No. 252. 
of glaciers in a region of valleys such as the 
Alps might very plausibly be affected by changes 
of this kind, it is not so apparent that the broad 
marginal oscillations of the ice-sheet of North 
America, for instance, can be explained in this 
manner. 
We next find a brief chapter on the work of 
underground water. Several simple and readily 
devised means are adopted for imitating the 
leading features in the production of water- 
worn channels, tunnels and the striation of peb- 
bles en masse through movements initiated by 
the washing out of supporting materials. The 
author indulges in some animadversions upon 
the nature of the scratched drift of the pre-alps 
of Europe and holds to the opinion that much 
of the so-called glacial drift of that region is 
really material striated in mud-flows—of which 
subject there is more to follow. 
Eolian denudation is passed over with a few 
references to the geological work of the winds 
and to the well-known experiments of Thoulet. 
The term abrasion employed in a technical sense 
for wind erosion has not so extended a use 
among English-speaking writers as the author 
evidently thinks. Walther’s term deflation is 
the only one apparently commanding anything 
like general use. i 
The processes of sedimentation receive a well- 
deserved attention. In this connection the 
author devotes several pages to the subject of 
mud-flows, a feature of many moist mountain 
regions which has been given evidently too 
little attention by geologists, but which is hardly 
so important a factor as the author intimates. 
There are a number of experiments described 
to show the rate of falling particles in water ; 
and small points bearing on the criteria of 
horizontality in the deposition of certain strata 
are brought out. None of these precautions, 
however, appear to have escaped the attention 
of field geologists and the author here, as else- 
where, seems to have been forestalled in many | 
of his discoveries. The statement that floating 
trees in large rivers sink root downward and 
thus may be buried upright giving the appear- 
ance of buried forests appears to pertain to ob- 
servational geology. There are experiments to 
show the amount of water included in sedi- 
ments. A frequent defect of the book is the 
