Great Ice- Dams. — Taylor. 17 
In 1897 the writer made a reconnaissance of most of the 
area bordering the east side of lake Huron south of Georgian 
bay and found there the continuation or complementary part*s 
of four of the Michigan moraines. The Detroit moraine was 
traced nearly 200 miles and the Port Huron about 15c miles 
from the St. Clair river. Southeast of Point Clark both of 
these turn towards the northeast running in roughly parallel 
lines. North of this part of the Port Huron moraine two 
others were found also running in the same direction. The 
first one corresponds to the Alcona moraine of Michigan. It 
passes close north of Lucknow, Walkerton and Hanover. The 
second begins northeast of Point Clark, passes close north of 
Chesley and Holland Center and corresponds to the Hagen- 
ville moraine in Michigan. All four of these moraines trend 
northeast towards the promontory of Blue mountain west of 
Collingwood. Part of a fifth moraine still farther north was 
seen between Southampton and Allenford, but its course was 
i:ot certainly made oui. 
Here, then, is a consecutive series of five moraines of re- 
cession running north from the same starting point as that of 
the similar series of seven which Mr. Leverett found running 
towards the east. By beginning at the point of common origin 
and setting ofT the successive pairs of moraines in the two 
series, vve are enabled to note accurately the location of the 
ice-dam at each step of its retreat. 
Location afid Dimensions of the Ice-dafn at its several 
Halting Places. 
The Defiance Dam. The Defiance moraine show's that 
the ice-dam at that stage presented an evenly curved front, 
such as is characteristic of a single, simple ice-lobe. Never- 
theless, it is certain that this particular lobe was compounded 
of two united ice-streams coming from different directions — 
from the Erie and Huron basins respectively. Some time be- 
fore reaching Defiance, however, the two streams had evidentlv 
become perfectlv blended in one, so that the dual source of 
the lobe was no longer expressed in its frontal form. When it 
stood at the Defiance moraine, the ice-dam was nearly 100 miles 
long and the water at its apex was about 60 feet deep. 
The Toledo - Neivbiirg Da)ii. The next moraine in the 
