The Loess and the Lansing Man. — SJiiinek. 363 
proof has yet been furnished that the Lansing loess is contem- 
poraneous with the Iowan drift. 
The attempt which Upham makes* to divide the loess into 
an aeolian "upland loess" and an aqueous "valley loess," which 
is practically a repetition of Hershey's effort,'!' is not success- 
ful. He says: ". . .the winds. . .blew away much of the fine 
loess dust and spread it far and wide over the interfluvial high- 
er lands." Unfortunately the interfluvial lands are often lower 
than the loess ridges along the streams. As the loess recedes 
from the streams it usually becomes thinner and its materials 
finer, both of which facts can probably be accounted for by the 
greater distance from the source of supply of the material, — 
the bars of the streams. He further states that "In these great 
areas of eolian loess only terrestrial shells are found." As a 
matter of fact most of the loess remote from streams (the "up- 
land loess") is non-fossiliferous. However, where fossils do 
occur the\- are chiefly, or wholly, terrestrial. But so are the 
fossils from Natchez and Council Bluffs; so are the fossils of 
by far the greater part of the lotss wherever it is found. \'o 
line of demarkation, vertical or horizontal, can be drawn be- 
tween two such divisions of the loess. There certainly is noth- 
ing known at present to indicate genetic differences. 
Hershey (1. c.) attempted to separate the upland non-fos- 
siliferous loess from that which is fossiliferous, but the pres- 
ence or absence of fossils does not prove difference in origin. 
This point has already been sufficiently discussed by the writer. :|. 
Neither differences in altitude nor differences in fossils offer 
satisfactory characters for a division of the loess, for both fail 
when subjected to the only reliable test, — namely, application in 
the field. 
Differences in composition and texture may frequently be 
observed in the loess. It is evident that not all loess is of the 
same age as measured with reference to the several drift sheets 
which have extended southward into the latitude of Iowa. The 
deposition of loess has continued through all the intervals of 
the ice. In the more northerly regions (i.e. Iowa, etc.) over 
which the several ice-sheets passed, there were more or less 
♦Am. Gbol . 1. <•.. p. 29. 
fSee Am. 01:01... vol. xxv, pp. 369-374, 1900. 
iThe Distribution of Loess Fossils, Proa in. Acad. Sci , vol. vi, pp. 98- 
103, 1899; Jour, of Geo /.. vol. vii. March, 1899. 
