IOWA ACADEMY OP SCIENCE 
199 
As is well known, tlie topography of Iowa is essentially that of an ex- 
tensive plain. It is described by Calvin'^ as follows : 
The zero point on the river gauge at Keokuk has an elevation above tide of 
477 feet; the elevation of Sibley, the highest important railway station in Iowa, 
is 1572 feet. It is possible that Ocheyedan mound or some of. the morainic pro- 
tuberances in Osceola County rises 100 feet higher than Sibley, but even then 
there is less than 1200 feet of difference between the lowest and highest points 
in the state. One hundred feet is gained at once by ascending the bluffs at 
Keokuk and passing on to the upland a short distance northwest of the city, 
so there is left but about 1100 feet as the sum of all the variations in level 
occurring over the general surface of the great state of Iowa. There are 
stretches, many miles in extent, so monotonously level that differences in alti- 
tude are scarcely perceptible. 
While the state as a whole is thus a plain, it does not exhibit the tab- 
ular smoothness of the plains area to the westward. This is due to the 
fact that the region was large glaciated duringdhe Glacial Epoch. Prom 
the standpoint of the region under discussion, the last ice-sheet, the 
Wisconsin, was the most important. It entered the state from the north, 
and on its retreat left extensive deposits of morainic material in the tri- 
angular area which it occupied. CalviiT defines the area glaciated by 
this ice sheet as follows : ‘ ‘ The base of the triangle, where the compara- 
tively narrow ice lobe crossed from ]\Iinnesota to Iowa, extends from 
Worth county to Osceola ; the apex is at Des iMoines. Through the 
western part of A¥orth, Cerro Gordo, Franklin and Hardin counties 
the edge of the Wisconsin drift overlaps the Iowan one ; the apex of the 
Wisconsin lobe rests at Des Moines on the older Kansan. The Wisconsin 
area is in general a level ill-drained plain. The traveler may go for 
scores of miles Avithout seeing a definite drainage trench so much as a 
foot in width or depth? Saucer-shaped depressions or ' kettle holes, ’ 
varying from a rod or two, to an eighth or a cpiarter of a mile in diam- 
eter, are common features of the Wisconsin plain.” IIoAvever, the Wis- 
consin ice sheet also formed large terminal moraines, and a Avell defined 
belt Avas developed along the Avestern margin of the drift area, extending 
from Osceola, Dickinson and Emmet counties through eastern Clay and 
Avestern Palo Alto counties to Guthrie county. In Clay and Palo Alto 
counties the topography consists of alternating hills and ridges — often 
150 to 200 feet high — Avith inteiwening depressions containing meadows, 
lakes, ponds, or SAvamps according to the depth and drainage. A de- 
tailed description of the physiography of these tAVO counties may be 
found in Volumes XI and XY of the loAva Geological Survey reports. 
The northwestern part is both the driest and coldest in the state. Ac- 
cording to Sage" there is an east to AATst and soutli to north decrease in 
*Loc. cit., pp. 258-259. 
•'■’Sase, John R., Climatolosy of Iowa. The Iowa State Atlas (1904), pp. 259-260. 
