Quaternary Geology.— Gordon. 18 
served. This may be accounted for by the exfoliation which they 
have suffered. Moreover, those rocks which have suffered little 
from this cause, were probably borne along within or upon the 
ice, Mr. Guthrie has shown* that boulders thus inclosed are con- 
stantly rolling upward in the same manner that the coarse mate- 
rial in roily water is whirled upward and outward to be deposited 
along the banks, or transported to some quiet resting place. 
Loess. —A cutting at the corner of Second and Des Moines 
streets not far from the above locality, discloses the following 
arrangement: 
SECTION III. 
7. Fine, dark drab or ash-colored material, becoming coarser 
below, and gradating into No. 6...... Deemer wats —. O Leet 
6. Coarse red sand, mingled with finer particles; approaches 
a red clay in places......... Louis acs a Suet ora eratete Sera atsh at 10 feet 
5. Fine white sand, interstratified with hard red iron oxide 
handeriromel tow) imehes! thick .; ....¢. sce... cael wc eres 14 feet, 
4, The boulder bed underlying the above shows its relations 
ne REreCeGINE BECtION:|....5. 2... .250¢ ccc sacsancecees ? 
Ferruginous Zone.—The uppermost division presents the typical 
characteristics of loess. No. 5 and the lower part of No. 6 are 
more or less stratified. No. 5 is made up of white quartz grains 
varying in size from 1 to 4 mm. in diameter, those above 2 mm. 
predominating. They are more or less rounded in outline, though 
angular forms are not wanting. The red bands show no variation 
except in the presence of cementing material in the form of iron 
oxide. No. 6 differs from No. 5 in the added presence of grains 
from 4+ to 10 mm. in diameter, and an abundance of iron oxide 
and finer particles. Under the microscope the oxide may be seen 
coating the sand grains, and in masses, along with the smaller 
particles, filling the interstices between the coarser grains. A 
vertical cut through the bed exposes small cavities with hardened 
walls, partially filled with clean white sand. The same white 
grains may be obtained from the main mass by dissolving the 
oxide with hot hydrochloric acid, thus indicating the probable 
origin of these pockets in a leeching process, due to waters 
charged with organic acids derived from the decaying vegetation 
above. Rounded grains are common. The decided coloration is 
a prominent feature of this bed. Wherever laid bare it is easily 
traced for long distances. Just above Warsaw, on the Illinois 
*Lake Michigan Glacier, p. 11. 
