ll4"_' The Amerh'dll Oeolofjlsf. October, 1H91 
vt'iy lu'iir tlic U'c-sheot. which allows an iiiterwi'aving of organic 
anti lilacial deposits. 
Mr. (J. K. (iii.HKHT remarked that in Alaska, according to Mr. 1. (V 
Hussell's ohsorvations, the waning ice-sheet l»econies covered with 
<hift and even with a growing forest, in wliich V)ears and other ani- 
mals live. 
Dr. Carl Diknku suggested that intercalated beds of sand are no 
positive proof of interglacial epochs. In the Austrian Alps moraines 
no more than twenty years okl are covered with pasture, and in 
the Caucasus the rhododendron grows to the very edge of the ice. 
l)r. N. 0. HoLST mentioned two moraines separated by inter- 
polated sand, and thought that they might })oth have l)eeii formed 
by the same ice-sheet. The melting of the ice leaves an unoxi- 
dized ( blue ) ground-moraine, with an overlying oxidized ( yellow ) 
upper moraine. This also occurs in northern Sweden, where 
there is no indication of a retreat of the ice. 
Baron de Geer could not understand the occurrence of thirty 
or forty feet of stratified sand between two moraines of the same 
glacial epoch. The colors are sometimes the reverse of what has 
been stated 1)V Dr. Hoist, and the boulders in the two moraines 
have V)een derived from different sources. 
Mr. James C. Christie descril)ed the section of peat and silt be- 
tween two layersoftill,occurringonthe river Clj'de above Glasgow. 
Mr. Henry M. Cadell reported five distinct layers of till oc- 
curring in a preglacial river channel in eastern Scotland; and also 
mentioned another river channel, filled with coarse gravel derived 
from rocks occurring farther north in Scotland, which was covered 
with a later layer of boulder clay. 
Mr. W J McGee mentioned the importance of land forms in 
interpreting geologic processes. Any primary geologic classifica- 
tion must be genetic, but he pi-eferred a comprehensive scheme of 
classification of all Pleistocene formations, whether of glacial or 
other origin, making thus five classes: A. Aqueous; B. Glacial; 
C. Aqueo-glacial; D. Eolic; and E. A'olcanic. 
President Cha.mberlin, in closing the discussion, said that 
there is great difficulty in applying a chronologic classification, 
and that such a classification may even act as a barrier to o])serva- 
tion and to the recognition of the truth. Chronologic classifica- 
tion is the ultimate goal of glacial studies. l)ut it is something for 
which we are not as yet prepared. Red, oxidized subsoils are 
