THE 
AMERICAN GEOLOGIST. 
Vol. XXXIII. APRIL, 1904. No. 4. 
EVIDENCE OF THE AGENCY OF WATER IN THE 
DISTRIBUTION OF THE LOESS IN THE 
MISSOURI VALLEY. 
By G. Fredbkick Wright, Oberlin, Ohio. 
PL\TES VII-VIII. 
[Read at the late meeting of the Geological Society of America, St. Louis, 
Mo., Dec, 1903] 
In a series of papers, representing the results of wide ob- 
servation and minute knowledge of the species of fossils found 
in the loess, professor B. Shimek* arrives at the conclusion 
that the loess of the Missouri and Mississippi valleys is largely 
an aeolian deposit ; derived, indeed, from the sediment brought 
down by Glacial floods at various stages of the recession of the 
ice, but elevated to its present position through the agency of 
wind. The principal evidence in support of this theory is found 
(i) in the absence, in the deposit, of shells belonging to dis- 
tinctively water species; and (2) the presence of land shells of 
species that live on the shores of ponds; (3) in the difficulty 
of imagining a submergence of the loess-covered area of such 
character as to account for its peculiarities ; for in a perman- 
ently standing body of water the uniformity of distribution of 
material of the given degree of fineness characteristic of the 
loess could not be secured ; (4) the reasonable influence of 
vegetation in arresting wind-blown dust. This was indeed an 
ingenious reversal of a former opinion. It had formerly been 
*"A Theory of tho Loess." Proc. Joxca Acad, of Sci., vol. Ill, 82-90, 1895 ; 
"Additional Observations on Surface Deposits in Iowa." vol. iv. 68-81, 1897 • 
"The Distribution of Loess Fossils," vol. v, 98-113, 1898 : "The Distribution 
of Forest Trees in Iowa." vol. vil, 47-59, 1899 : "The Loess of Natchez, Miss.," 
AM. Geol.. vol. XXX. 279-299. 1902: "The Loess and the Lansing Man." Am. 
Geou. vol. xxxii. .-^.-r! .'ifiO. 190.S : "The Distribution of Tx)ess Fossils," Jour of 
Oeol., vol. vii, pp. 122-140, 1899. 
