The Second Lake ^Mgonquin. — 'Vdijlor. 173 
the river to carry sand therefore has probably been gradually 
decreasing as drowning progressed. The Nipissing plane 
projected southward to the mouth of St. Clair river, passes 
about 35 feet below its present level and below the bottom of 
the shallow lake. It follows that the delta above that level 
has been built since the eastward uplift began, and this im- 
plies a considerable lapse of time. It therefore puts the be- 
ginning of the eastward uplift relatively a long wa}"^ back 
from the present day. But that is probably all it does. It 
reveals very little as to the present or very recent status of 
deformation, unless the one to three feet of water which now 
covers most of the delta may be taken to shov,- a very recent 
drowning. As to tlie ])robable character of the most recent 
change, however, good evidence of another kind is close at 
hand. It was pointed out above that a northward ditleren- 
tial elevation ati'ecting the whole basin of the lakes as a rigid 
vessel would cause their plane to swing on an east-west axis 
passing through Port Huron. It follows that if there has 
been a very recent predominance of northward over eastward 
uplift, it ought to be recorded on the lake shores north of the 
Port Huron axis and south of the node line A A. The long- 
est shore comprised between these lines is the west shore of 
lake Michigan. It is much the most favorable, and I have ex- 
amined part of it closely. The appearance of that shore be- 
tween Sheboygan and Two Rivers is described in the third 
paper of the above list. It shows no sign of a recently aban- 
doned northward-rising beach, but affords instead i)ositive 
evidence of present or very recent encroachment of the lake 
upt)n the^land, showing apparently that the very latest phase 
of deformation has been eastward more than northward ele- 
vation, raising the outlet at Hulfalo and consequently the level 
of all the waters west of it.* 
At Mackinac and in the vicinity of the straits there is ap- 
parently an old water plane now submerged five to ten feet. 
It is seen in the wide submerged rock shelves anil in numer- 
ous gravelly shoals in the atljacent parts of the lakes. But 
not enough is known of its character to be of much use in 
*This fact may ri'iiuirc H iv)iisidi'i-iil)lc motlificalioii of Dr. Andrews' 
t'stimati' of poslirlacial linif based on the erosion of lliis sliori'. (<Juoti'd 
by various writiTs from tiie jiaper nieniioiied above. 
