The Second Lake Ahjonqifiii. — T(i///or. lOJJ 
to suggest that the plane rises northeastward to an anticline 
or a fault. This, in turn, suggests that the inclination of the 
plane probably dies out toward the southwest somewhere be- 
yond the node line and passes into a dead level: that is, into 
ground that w^as not affected by the change which produced 
the deformation. The attitude of the main plane is substan- 
tially such as it would be if it were the foot- plane of a simple 
northeastward uplift, and had been dragged up incidentally 
with a more sharply raised region hnng farther to the north- 
east. Reasoning solely from the attitude of the nuiin plane, 
the ratio of the northward component of elevation to the 
eastward component is about 19 to 8, or a little less than 5 to 
2. But there are certain facts which show tliat the change 
was not so simple as this. If we examine Nipissing beach 
closely we find that its structure proves that for at least 25 
feet from its upper level the water must have fallen away 
with extreme slowness and apparently at a perfectly uniform 
rate. This is shown at Au Train. Sand River, Marcpiette. and 
other places on the Superior shore, where the beach ridges of 
a numerous series are strong and very regular.* Spencer, as 
quoted above, reports much the same appearance on the shore 
of (jeorgian bay, and Lawsou describes several such places on 
the north Superior shore. (Jonsidering the difference in the 
materials of the beaches, the case is almost as good at Macki- 
nac and Gros Cap. These features exclude -certain supposi- 
tions that might be made as to the character and order of the 
changes producing deforuuition. And among others they 
exclude the supposition of a simple northeastward uplift as 
given above. That idea seems fair enough at a glance, but it 
is based solely on a consideration of tlie attitude f)f the plane, 
without any reference to other evidences which may require a 
different explanation. 
The Order of Cha rujes. The order of events appears to have 
been about as folloM's : P\)r a long period of time the upper 
lakes were in open connection with the ocean through several 
straits, the deepest being the one over Nipissing pass. Tiiis 
strait had a minimum width of 2o miles and a maximum 
depth of nearly 500 feet. Not until the waters had fallen 
away from this high level to that of the Nipissing pass, did 
*Fovirtli iiapiT. pp. Ii()(i-:!71. 
