IOWA ACADEMY OP SCIENCES. 
61 
of glaciated rock in this region, and pointed out that the testi- 
mony they gave was unanimous as to the southeastern move- 
ment of the ice sheet. Since then another exposure has been 
located that seems to bring conflicting testimony. 
This locality is the joint discovery of Mr. Frank Leverett 
and myself. It is situated on the lot at the northeast corner of 
the intersection of Court and Prospect streets in the city of 
Burlington. Some quarrying had been done by blasting out 
the level rock floor. Everywhere on the margin of the hole 
thus formed may be seen the finely striated and grooved sur- 
face. On the east side a patch, 6x8 feet, was cleaned off and a 
finely striated surface brought to view. The direction of the 
striae, taken with compass and corrected, was S, 79° W. This 
would indicate an almost due westerly movement, which is in 
direct variance with that shown by all other discoveries of gla- 
ciated rock in this region. If direction of strice alone were taken 
into consideration, then it might be claimed that the ice move- 
ment in this case also was towards the east. But a close and 
critical examination shows that all the accompanying phe- 
nomena point to a westerly trend; e. g., the indicated move- 
ment of the ice around and over a prominence, and down into 
and out of a depression. 
This is new and important evidence that the Illinois lobe of 
the great ice sheet crossed the Mississippi river and invaded 
Iowa. It will be remembered that I presented a paper on this 
subject at our last meetii g.^ The evidence on which the claim 
was based was the presence, on the Iowa side, of boulders of 
Huron conglomerates. I was convinced that this westward 
movement was not the latest in this region, but that the ice 
moving from the northeast was the last to hold possession of 
the west bluff of the Mississippi; and I so put forward in the 
paper. Mr. Prank Leverett, who has made an exhaustive study 
of this question, is of the opinion that the Illinois ice sheet was 
the last to invade this portion of Iowa, and that the movement 
extended to some twenty miles west of the river. This recent 
discovery of glacial scoring certainly strengthens his theory. 
For it is situated at such an elevation that any ice sheet passing 
over would be almost certain to leave its impress; and there- 
fore the striae we now find are very apt to be those made by the 
latest invasion. 
^Extension of the Illinois Lobe of the Great Ice Sheet Into Iowa. Proc. la. Acad, 
Sci., Vol. II, p. 309. Des Moines, 1895. 
