SUMMARY AND CONCLUSIONS. 181 
the gorge from one end to the other. Asin Rock gorge, they are cut in 
rock except at the eastern end, at the place of debouchment into the main 
valley, where they are cut in the sides of a clastic, delta-like deposit of 
adjacent material. There are here three principal terraces, which are 
themselves traversed by subordinate terraces. 
The evidence here of active and extensive water work leaves little to be 
desired. The large quantities of water which at one time must have been 
here to have created channels and terraces on so large a scale as those we 
find would have produced a river of considerable size, though apparently 
much smaller than the present Niagara. The estimation of its volume 
is, however, a matter of considerable difficulty. 
SUMMARY AND CONCLUSIONS 
The origin of the fissures, caves, and channels which occur in the 
vicinity of Jamesville lake seems to be sufficiently well accounted for 
without a more detailed study. The kettle-like depressions which dot 
the region are more difficult of explanation. In speaking of them I have 
refrained from using the term sinkhole, although the term suggested 
itself at the outset on account of the strong resemblance of many of these 
depressions to the sinkholes of the limestone cave district of Kentucky ; 
yet others do not resemble them. For example, several of the largest 
depressions hold or have recently held standing water, and do not seem, 
therefore, to lead into underground fissures or caverns. Again, in the 
northeastern part of the field depressions occur similar to those described, 
but in glacial clay, while side by side with them are those excavated in 
Helderberg limestone. In attempting to account for these kettles it is 
important to recall that they lie in the path of postglacial rivers of large 
volume ; that the waters were moving from west to east, as shown by the 
delta-like accumulations; that the depressions occur in a region where 
hard and resistant rocks cap thick beds of soft and friable rocks, the strata 
tilting slightly upstream ; also that the west (upstream) bank of the de- 
pression is usually steep and high and the east bank cut away. In short, 
the conditions are favorable for the formation of waterfalls and indicate 
their former presence, the depressions occurring in nearly every case at 
what might have been the foot of a waterfall. In other words, if we could 
today turn a good sized river across this plateau and through these chan- 
nels there would be a waterfall formed at the west side of nearly all of the 
depressions. 
The cave theory for the formation of these depressions has been re- 
ferred to above. The fissures and caves which occur all through these 
rocks show that the dissolving power of the percolating waters has been 
XXVII—Burt, Groz, Soc, Am., Von, 9, 1897 
