APPENDIX. 
G63 
distance was excavated to the depth of six feet. Two or three small falls along the stream have 
receded several rods, and huge fragments in immense numbers were tom from the sides of the ravine. 
The whole of this accumulated mass of earth and stones was forced out from the mouth of this ravine 
into the level valley of the Chenango; and after the water subsided, an extent of fifteen acres was found 
completely covered to the depth of from one to five or six feet. The thin-bedded sandstone from the bed 
and banks of the ravine lies in slabs of two to four feet in length and breadth. Boulders of limestone, 
sandstone and other northern rocks, are confusedly intermixed with the other materials. One of the 
boulders of limestone lying near the centre of this area of fifteen acres, I estimated from measurement 
to weigh about eight tons, and there were numerous smaller ones, and others of the Oriskany sandstone 
of three or four tons. The uprooted trees, and the timber of two mills which were destroyed in the 
course of the stream, were scattered over an extent of fifty acres. The passage of this body of water 
through the ravine occupied four or five hours, and nothing could exceed the grandeur of its resistless 
force. 
What has here resulted from an artificial dam, may easily happen from natural causes. Many 
of our ravines open into broader valleys above, and a great body of snow melting in this situation and 
pressing toward the outlet, would carry forward any prostrate trees; these accumulating in some narrow 
passage would form a temporary dam, which, when broken away by the increasing pressure, would 
add new materials to form a stronger one at the next narrow pass. In this way the same scenes may be 
enacted as in the case just described, and the bed of a ravine or stream may be deepened several feet 
in a few hours. 
The process here described, with others before mentioned, operating through ages, is sufficient to pro¬ 
duce the deep ravines which we now find, though the quantity of water flowing in them may never have 
been much greater than at present. The actual amount of excavation produced in this way is immense, 
and I am perfectly satisfied that the same causes have always operated from the incipient stages of these 
deep gorges to their present condition. In favorable situations, large and comparatively permanent lakes 
may have been thus formed, and their subsequent bursting produced the phenomena attributed to lakes 
originally remaining on the higher ground. 
( D. ) 
Elevation of Lakes. 
The following memorandum of the elevation of some of the smaller lakes was mislaid at the time that 
chapter passed through the press. These elevations were furnished by Mr. Healy, an engineer on the 
New-York and Erie railroad. 
FEET. 
Bear lake summit. 755.4 above Lake Erie. 
Cattaraugus lake summit. 725.5 “ “ 
Mud lake. 833.7 “ “ 
Cassadaga lake. 725.0 “ “ 
Leavenworth summit, between the valley of 
the Little Connewango, in Randolph, and 
the Allegany. 859 “ “ 
