MORAINES OF RECESSION 435 
This is distinctly the character that should be expected in 
moraines built at a climax of advance in which the advance, the 
halt and the subsequent retreat take place after the manner of 
the cold climax of an oscillation like that shown at 4 in Fig. 1 
above. The crest of the ridge is toward the front edge, the back 
slope is long and gentle, while the front slope is shorter and 
wa) 
SO 
Glacial Flow  & b: L 
ie ~ > SOOT ES 
a re ea 
DICE: an wae 
[io ae ea ee er) 
400 feet above datum 
40 miles from Toledo YS 50 
Fic. 2. Profile of Defiance Moraine. 
steeper. This type of moraine is well illustrated in cross section 
by the profile of the Wabash Railway as it passes over the 
Defiance moraine east of that place. This is shown in Fig. 2. 
As shown on this profile the crest of the moraine rises above 
liberal an allowance of time for the glacial retreat as this hypothesis would seem to 
require. Moreover the moraine series remained fragmentary and incomplete until a 
year or so ago, so that there was not a sufficient foundation of fact to warrant the 
presentation of the idea. Nor had the remarkable Greenland explorations of Cham- 
berlin, Salisbury, and others furnished the present strong foundation for the idea of 
slow motion of ice-sheets and slow transportation and deposition of drift. Without 
adopting the idea of precession as a cause, Professor Dryer fully recognized the gen- 
eral significance of the moraines, as the following words from his report show. After 
speaking of the possibility that each moraine marks the culmination of a separate 
glacial epoch, he says: ‘It seems more probable, however, that they are moraines of 
recession and mark halting places in the retreat of one and the same ice lobe. When 
their uniformity of mass, strict parallelism and occurrence at regular intervals are 
taken into account, the whole arrangement will perhaps prove to be unique among 
the glacial phenomena of North America. Their greatest importance lies in the 
evidence which they afford of regular periodical oscillations of climate. The outer 
edge of the ice lobe occupied a certain position long enough to form a moraine five 
miles wide and I1oo feet high; it then fell back fifteen miles and occupied another 
line long enough to form a similar moraine. These alternating halts and retreats 
were repeated four or five times, the last retreat being thirty [fifty ?] miles, and the 
last moraine, the Blanchard Ridge of Winchell, being smaller and less symmetrical” 
(p. 124). 
