TODD: PLEISTOCENE CRUSTAL MOVEMENTS. 379 
quite as plausibly it may be ascribed to a Post-Kansan eleva- 
tion of the region. It need hardly be stated that along the 
Missouri through the Carboniferous rocks, bedrock is rarely 
more than 50 or 60 feet below low water. In some shaly por- 
tions and in the soft Cretaceous sands and clays of the north it 
is 100 to 125 feet below. 
We can conclude, therefore, that the crust was raised at 
least 100 feet in Kansas, and depressed 100 feet in eastern Iowa 
and Wisconsin, or a total relative movement of 200 to 600 feet 
of eastern subsidence since the time of the Kansan ice sheet. 
May not the less easterly movement of the ice of that time be 
further accounted for by a more rapid rise of the underlying 
rock surface on the east and the southeast? May not the south- 
westerly trend of the low ledges traversing the eastern part of 
Kansas, with the corresponding direction of the tributaries of 
eastern streams, have had an appreciable effect, favoring the 
westerly movement of the ice in that region? May not the 
greater heating of the western half of the ice lobe, whether 
from the maximum daily water temperature coming in the 
afternoon (see Science, new series, vol. 14, pp. 749-1901), or 
from the warm southwesterly winds, have rendered the west 
half of the ice sheet more active, and so increased its westerly 
movement. 
LAWRENCE, KAN., December 21, 1910. 
