AKI. ILA SSAC: 559 
soil would come whatever deposits were made in the lake basin 
during the later glacial invasion. So far as known, such an old 
soil does not exist, but observations are not numerous enough to 
prove its absence. 
(3) The third hypothesis differs from the second only in the 
assumption that the inter-glacial lake lasted until the later ice 
invasion, and was continuous in time with the lake formed in 
consequence of that ice invasion. 
The first hypothesis makes the clays, so far as they are 
lacustrine, entirely late-glacial. The great objection to it is the 
very long time required for the advance of the ice, in order to 
permit the formation of so great a body of clay, compared to the 
brief time of its maximum extension and retreat. The retreat 
must have been rapid, since the silts and sands correlated in time 
of origin with the moraine, are not buried by later deposits. The 
second hypothesis makes most of the clays early glacial and inter- 
glacial, and seems to demand an old soil separating these 
deposits from later ones. Sucha soil is not known to exist. The 
third hypothesis makes most of the clays early glacial and inter- 
glacial, and it demands their transition upward into the later 
deposits without a break. Sufficient data are not available to 
permit a decision in favor of any one of these hypotheses. 
DEFORMATION OF THE LAKE BASIN. 
The highest shore-lines of Lake Passaic are no longer at a 
constant elevation with reference to the present sealevel. At 
the southern end of the lake, the highest shore-line has an 
elevation of 345 feet;* at the Moggy Hollow outlet, about 356 
feet; at Morristown about 376 feet ; at Boonton about 394 feet ; 
at Montville about 398 feet; at Jacksonville, 408-9 feet; north 
of Upper Preakness, about 412 feet. On the eastern side of the 
lake the shore-line increases in elevation from south to north. 
At Mt. Bethel it has an elevation of 350 feet; at West Summit 
t Elevations in most cases were determined accurately by two men working with 
a rod and level, from bench marks established during the topographical survey of the 
State. 
