MORAINES OF RECESSION 459 
When the ice-front was at the Hagenville (15th) and Alcona 
(14th) moraines, the apex of its lobe in the Huron basin was in 
the present lake bed, and so cannot now be exactly located nor 
measured. But at the next halt the ice-front stood at the Port 
Huron-Saginaw moraine (13th). This is the first one now fully 
recorded on land. At that halt the ice was held back by the high- 
lands south of Georgian Bay in Ontario, and by those southeast of 
Petoskey in Michigan, and it was also held back about fifty miles 
by the “thumb” of Michigan. With further advances the separ- 
ated Saginaw and Huron lobes moved forward nearly equally at 
first, but soon the Saginaw lobe met higher ground, and slowed 
its pace, while the Huron lobe moved on more rapidly and met 
and blended with the Erie lobe coming up the Erie basin from 
the northeast, and the two advanced as one lobe up the Maumee 
valley. The ice clogged more and more against the high ground 
in southeastern Michigan, and began the building of a great 
interlobate moraine upon it. This obstructed the advance of the 
Maumee lobe pretty effectually on the northwest side, while the 
high ground along the south side of the Erie basin did not allow 
of much expansion on that side either. Hence the advance was 
mainly up the wide flat Maumee valley until Fort Wayne was 
reached. At this point there came an important change. The 
ice-front had almost reached the flat rim of the Erie basin along 
that part of the front line which extends from Fort Wayne east- 
ward about 140 miles, nearly to Mansfield, Ohio—to the east 
side of the head of the Sciota valley. The subsequent advances 
found ample room for expansion in the most advantageous way ; 
that is, in a southerly direction and down grade. The ice soon 
began advancing down the Wabash and White River valleys in 
Indiana, and down the Miami and Sciota valleys in Ohio. 
Besides, the Maumee lobe had now pushed so far ahead of the 
Saginaw that the obstruction on its northwest side in Indiana had 
been somewhat relieved. But before becoming distinctly segre- 
gated into four sub-lobes, the ice advanced for a few steps very 
evenly over the level summit plateau, forming the remarkably 
regular and concentric series of moraines south of Fort Wayne 
