398 The American Geologist. June, 1892 
As both these localities were within the glaciated area, and es- 
pecially the latter, on the same level with striz commonly re- 
ferred to the action of land ice, their origin remained undecided 
in my mind. 
I sought for light upon the problem at every opportunity, as 
on limestone ledges along the Platte and Missouri rivers, but in 
vain, 
During the past season, it was my privilege to visit Cape 
Girardeau, Mo., and Grand Tower, Ill., while employed on the 
geological survey of the former state. At Cape Girardeau, I 
found upon the ledges a little above low water, numerous scratches 
several inches long, having a direction S. 10-35° E., correspond- 
ing to the course of the river opposite. Here again there was 
doubt as to their origin, because although beyond the limits of 
extreme glaciation, it was not impossible that they might have 
been formed by artificial means, the slipping of pike or anchor, 
or the grazing of boats. They were near the main landing. 
The next day, I was rejoiced to find a much finer exposure of 
similar markings, about three miles above Grand Tower, on the 
east side of the river. Here everything seemed to conspire to 
give an unequivocal affirmative answer to the question, whether 
river ice did ever striate rocks. 
There is there a hard, even-topped stratum of dark limestone, 
jutting from the bank several yards, and dipping at a slight angle up 
stream and toward the bank. The steep bank, upon it and ex- 
tending further up the stream, is faced with large sandstone 
boulders. The dip of the rocks is 4-6° E. NE. The principal 
seams of the rock are N. 10-12° E. The surface, which was 
quite generally planed and striated, was 10 feet wide on an aver- 
age, and 60-75 feet long. The direction of most of the striz 
was 8. 10-11° W., and of afew, S. 18° W. The striated sur- 
face reached from the surface of the water up 2-3 feet above 
that level. A small patch toward the lower end was scratched 
8. 56° E. The strie were, if anything, more strictly parallel 
than in most glacial striz. They were short, rarely more than 
three inches long. This was mainly due, it would seem, to the 
nodular and much cracked nature of the stone. One other pecu- 
liarity of the stone affected the form of the markings. Scattered 
through the rock were small black grains, as if of iron oxide. 
These usually headed the narrow ribs separating the striz. 
