SCD ILE S, PAO RS SINC EINAGS. Te 
not only negatively but positively overwhelming against the 
notion that the bulk of the drift can be accounted for by any 
phase of river work of any degree of intensity assisted by any 
other agent in a subordinate capacity. Streams, then, were not 
the principal agencies concerned in the deposition of the drift, 
though nothing here said is to be construed to mean that they 
did not play a subordinate part. The fact that stratified drift fre- 
quently extends much further south in valleys than on the adja- 
cent uplands suggests that rivers may have played a subordinate 
role in the transportation and deposition of the drift. 
Materials deposited by streams along their valleys are prop- 
etly called “river drift.” Generally speaking, river drift is so 
unlike the general sheet of drift under consideration, both in its 
inherent character and in its relations, that the one is not likely 
to be mistaken for the other. Yet the range of variation, both 
in the drift and in river drift, is great. When the variations 
are toward a common limit, as is sometimes the case, the one 
may Closely simulate the other. But this does not appear to be 
true of any considerable body of the two types of drift, extend- 
ing over any considerable area. Torrential deposits, such as are 
formed at the bases of steep mountain slopes, or along the val- 
leys of streams which have high gradients, may closely resemble 
the drift so far as their physical constitution is concerned. 
But the distribution of such deposits, the shapes of their con- 
stituent stones, and their freedom from striation and planation, 
are generally sufficient to betray their origin. Lithologically, 
too, torrential deposits contain only materials which might have 
been gathered from the drainage basin of the stream concerned, 
while the constituents of the drift are rarely so limited in their 
range. If the materials entering into the constitution of torren- 
tial deposits were derived from the drift, and not greatly modi- 
fied in the process of reworking, the resemblance of these 
deposits to the drift, and especially to the stratified drift, might 
be very close. Even in this case their distribution and structure 
might be decisive. Furthermore, if the existence of the drift 
must be presupposed in order to account for torrential deposits 
