2K1 The American Geologist, November, 1893 
that the ice <>!' the ponds with furrows much exceeded one 
hundred feet in altitude. 
It would be possible with good contoured maps in hand to 
prepare a bird's eye view of the successive stages of the ice 
retreat, by sketching in the sites of ponds and kettles the ice- 
masses which once protruded from them. With carefully 
conducted field observations, followed up by calculations on 
the rate of melting of ice and the volume of the excurrent 
stream shown by the furrows (knowing the horizontal dimen- 
sions of the outliers of ice), it seems possible to obtain more 
minute results than have been roughly outlined in this paper. 
In conclusion, it seems safe to say that, while there was 
every gradation in thickness of the outliers, we are able to 
indicate the site of blocks having a thickness of 100 feet or 
less, as well as to point out those masses which may have had 
an elevation of 200 or 300 feet above our sand-plains when 
these were fairly developed. 
OBSERVATIONS ALONG THE VALLEY OF GRAND 
RIVER, MICHIGAN. 
By E. H. Mudge, Belding, Mich. 
The lower peninsula of Michigan, as a field for glacial study, 
possesses many interesting features. The peculiarities of its 
surface configuration and the remarkahle courses taken by 
some of its rivers present problems worthy of thoughtful con- 
sideration. 
The latest state report bearing on this region was published 
in 187(5 by Dr. ('. Rominger, then state geologist. This re- 
port devotes a brief chapter to the topography of lower Mich- 
igan, with incidental reference to glacial phenomena; but, so 
far as the writer knows, no recognized authority has ever 
studied thoroughly the glacial history of this territory. Act- 
ing on the suggestion of Prof. Wright, in his work on "The 
ice Age in North America," that local observers may add 
something to our knowledge of this and kindred subjects, the 
following observations along the valley of Grand river are re- 
spectfully submitted. 
With a map of the state before us, let us note the course of 
