The Loess and the Lansing Man. — Shimek. 365 
loess was deposited under glacial conditions. To judge from 
his statement there is no clear distinction between the two de- 
posits, yet the statement that loess can be "in most cases cer- 
tainly identified by student and layman alike" is just as true as 
it was when McGee wrote it. It is true that at some points, es- 
pecially along the border of the Iowan drift, sand is more or 
less mingled with the base of the loess and that usually the line 
between the loess and the drift is not absolutely sharp, but this 
is precisely what would be expected under the aeolian hypoth- 
esis. The recession of the glaciers left the surface covered with 
till, boulders and sand. Along the drift-borders, and especially 
along the streams near the Iowan border, there were ridges of 
overwashed sand presenting sand-dune conditions perhaps not 
unlike those which now prevail along the Missouri near Mis- 
souri Valley and Modale, Iowa, and Blair, Neb., or along the 
Platte river near Freemont, Neb. As soon as a vegetation, at 
first scant, gained a foothold dust was retained more or less, 
but for a time stronger winds, perhaps in drier seasons, would 
occasionally sweep sand over the plant-covered areas, and a 
mingling of sand of different degrees of fineness, and of dust 
was the result. As vegetation gained a better foothold over 
larger areas these incursions of sand became less frequent, and 
finally ceased. Such mingling of sand and fine soils may be 
observed today at the localities named, and fine illustrations 
may be seen along the road leading east from West Point, 
Neb., where sand and loess, evidently wind-blown, are inter- 
stratified in various ways. At one point along this road fos- 
siliferous loess has been covered by wind-blown sand in com- 
paratively recent years. That the fine sands at the base of the 
loess sometimes (though rarely) contain fossils is not incon- 
sistent with the aeolian hypothesis. The writer has found liv- 
ing Succinea grosvenorii in mingled sand and loess on top of 
the high ridge northwest of Hamburg, Iowa. Some of th^ 
dead shells, still somewhat fresh, were already partly covered 
with dust and sand. Some of the sand so transported by wind 
today is coarse and even contains small pebbles. 
The "southern loess" discussed by McGee, whom Dr. Win- 
chell quotes so extensively, is the loess of the Iowan border in 
Iowa, and this rests upon morainic sands,* which must have 
♦Calvin. S., la. Geol. Sur.. vol. vii, pp. 88-9, 1897. Beyer, S. W., la. 
Oeol. Sur., vol. vii, p. 'J36, 1897; vol. x, p. 281, 1900. 
