CALL’S GEOLOGICAL WORK 
153 
Des Moines, in other parts of the state that they were not detected 
by subsequent investigators. Later, also, the loess itself was 
demonstrated to be not a deposit derived from the glaciers but a 
warm-climate interglacial formation. However, together, McGee 
and Call barely escaped making one of the great geological dis¬ 
coveries of the century — the establishment of the multiplicity of 
the Glacial Epoch. The Des Moines sections furnished all the 
evidence but they were mot properly interpreted. 
Call afterwards extensively studied the loess of the upper Mis¬ 
sissippi valley, and come to the conclusion that this remarkable 
loam formation was a great lake deposit, accumulating something 
after the manner of the beds of the alleged vast Tertiary lakes 
of the Great Plains region. Here again his judgment was at 
fault, for all of the deposits of this description were finally proved 
to be mainly epirotic formations laid down by the winds. His 
close association with government folk in the Far West evidently 
firmly implanted in his mind this early but erroneous notion. His 
views on this subject are elaborated in a series of articles which 
appeared in the American Naturalist. These papers were long 
worthy of careful perusal if for no other reason than that they 
supplied the best summary of our scant knowledge on the loess 
up to the date of their publication. 
Call’s monograph on the “Mammoth Cave of Kentucky” was 
a huge quarto tome, edition de luxe, sumptuously printed on 
deckle edge, antique wove, unsized paper, and contained 30 plates. 
Its character was historic, scenic, biologic, and bibliographic. 
During several summers Professor Call served as assistant geol¬ 
ogist on the Arkansas Geological Survey under Dr. J. C. Branner. 
His main work was on the Crowley ridge, a long narrow elevation 
of Tertiary formations rising out of the wide Mississippi flood 
plain in the eastern part of the state. The report was published 
as a special volume of the Survey series. 
When resident of Iowa Call became interested in the artesian 
waters and collected data of a number of deep drill-wells put^ 
down in various parts of the state. His principal results appeared 
from time to time in the Bulletin of the Iowa Weather Service. 
Many brief papers and articles were published on geological sub¬ 
jects in the scientific journals. 
Call published most extensively on the mollusks, fishes, and 
reptiles. A synopsis of the Unionidae of the United States formed 
