388 MeGee—Meridional Deflection of Ice-Streams. 
the southern to the northern margin of the plateau, and its ulti- 
mate coalescence, just before the final recession of the ice—with 
homologues. Here the deflecting agency manifestly forced the 
fluctuating ice-stream to burst its old barriers and build for 
itself a new pair of adequate curvature. : 
The southernmost of the five pairs of moraines issues from 
Parker cafion and extends two or three miles upon the long 
alluvial slope everywhere forming the periphery of the ee 
ey curve northward more sharply and iy diet 
the northern cafion-wall more closely than do those of Bloo 
cafion; but the right-hand member does not so greatly exce 
its fellow in magnitude. 
Let it be clearly understood that in these several cases the 
curved portion is well without the cafion proper and age we 
tionably beyond its influence, and that the curvature, so far 58 
can be detected by careful observation, is independent of if 7 
opposed to topographic configuration, whether ancient or paee: 
uniform behavior must have a common cause; and t 
may be sought analytically. 
IL.—TwHeE EXPLANATION OF THE PHENOMENA. 
Let an ice-stream flowing east or west on a meridional as 
lat. ° ha 
horizontal plain in N. lat. 45 1 ‘ 
ve by the transverse semi-circumference of an ellipse yin 
axes are 2 and 1 respectively; and let the sun be over or 
1 equator. The proportion of 5° 
; rays directly reaching th ‘ 
and north balves respectively Pcl 
