EXTENSION OP WISCONSIN DRIFT 
229 
THE EXTENSION OF THE WISCONSIN DEIFT SOUTH- 
WEST FROM DES MOINES. 
JOHN L. TILTON. 
At the last meeting of the Academy I called attention to an 
extension of the Wisconsin drift south past Valley Junction into 
the region which was generally understood to he within the area 
of Kansan drift. It was with a view to extending observations 
further south in that direction than was possible in the time 
previously at my disposal that trips were made in 1914 ex- 
tending the area examined east to the Army Post, west to the 
ravines in the southwest portion of Polk county, and as far south 
as Norwalk, Cummings and Orillia in Warren county and west 
to Madison county. 
In addition to the district of Wisconsin topography described 
a year ago, another equally distinct area has been found two 
miles to the south, in section 35, Nw. qr. of the Se. Here 
the eastern one of two small ponds is partly drained, but the 
one a few rods to the west is as distinctly characteristic of Wis- 
consin drift topiography as the one previously described in sec- 
tion 23. These two small ponds are faintly marked on the map 
of the Des Moines quadrangle. A mile to the west in section 
34, Sw. qr. of the Ne. % is another marshy area in the upland. 
This area is partly drained. The fact that the road extends 
across the outlet and that the small culvert is above the level 
of the pool suggests the suspicion that the water has been dam- 
med back by the road. Plowever, the bottom of the pool is 
slightly below the level that has been filled in, justifying the 
inference that here is a small upland pond that erosion had 
nearly but not fully drained. Several other ravines were noted 
headed in unusually dark soil along, depressions in the upland. 
One is in the south central part of section 23, within a quarter 
of a mile of the section line. Another is half a mile to the 
south, in the north central part of section 26. 
On the low ground in the eastern central part of section 22 
the map locates a small pond that is of a very different charac- 
ter than the ones above mentioned. This pond is located in the 
line of drainage along the foot of the hills bounding the river 
