Meetimj of the Ameriiuui Association. — Upham. 229 
by scattered sierras which are notably rugged: and since the general 
conformation of the provin(;e was shaped it has suffered southwestward 
tilting whereby the southwestward flowing streams have been stimu- 
lated and the northeastward flowing streams paralyzed to the extent 
that the divides are migrating and no longer coincide with the dominant 
topographic features. One of the striking characteristics of the prov- 
ince' is the ruggedness of the mountains and the sharpness with which 
they rise from the flat-lying plains: a still more striking feature is the 
structure of the plains — they consist of the planed edges of strata simi- 
lar to or identical with those composing the mountains, veneered with a 
thin sheet of mechanical deVjris, and are manifestly produced by wide- 
spread planation extending over the greater part of the province, i. e., 
the entire area except the central portions of the valleys, which are 
deeply lined with alluvium, and the scattered sierras which are rem- 
nants of an ancient plateau. 
On studying the process and agencies of erosion, it is found that the 
chief agency is storm-water and that active erosion is limited to a few 
consecutive hours or days during the semi annual, annual, or more 
widely separated storm-freshets. When such freshets occur the waters 
are quickly charged with mechanical debris, the products of past storms 
or of inter-storm disintegration: the overloaded freshets push slowly over 
the vast plains in sheets of muddy water: and whenever the viscid sheet 
begins to segregate in a stream its velocity and hence its transporting 
power immediately increase until it is overloaded more heavily than 
before, and within a few yards Vjegins to build up a delta by which its 
velocity is checked and its volume redistributed; so that the ultimate 
tendency of the flood is to continue in a sheet until the waters are lost 
through evaporation and absorption. Thus the characteristic form of 
water-flow is not in streams, but in sluggishly moving sheets which may 
be called sheetfloods: these are amply supplied with rock matter which 
is mechanically disintegrated rather tlian chemically reduced, and which 
is thus an efficient eroding substance; and throughout most of the re- 
gion the tendency of the storm waters is not to carve valleys, but to 
plane broad belts two to twenty miles or more in width. It seems cer- 
tain that this distinctive agency has produced the distinctive conforma- 
tion and structure of the province. 
■i:i. Olacial Flood Deposits in the Chenango Valley. ALBKFtr P. 
Brigham. The aqueo-glacial or modified drift deposits found in the 
Chenango and Oriskany valleys from Deansville, near Utica, to Bing- 
hamton, N. Y., are described as kames, eskers, kame terraces, frontal 
terraces, and valley trains, in this terminology following Salisbury. 
True till is found only on the main hill slopes. The kame terraces are 
deposits n)arginal to ice tongues, being the same as the lateral moraine' 
terraces of Gilbert. The frontal terrace is associated with kames, and 
in some cases is shown to be a true delta deijosit. It is a frontal apron 
of the valley type, and is closely related to the sand plains of Davis and 
others. Massive fine clays, underlying the valley train gravels, show 
lacustrine conditions of long duration, whose history is not vet deter- 
