224 
GEOLOGY OF THE FIRST DISTRICT. 
the bottom. The glacier theory, however applicable it may be in particular localities, will 
not apply to the broad level tracts of country like Ohio and Western New-York, where the 
rocks show no signs of disturbance of an amount appreciable to the eye, since their original 
deposition; and the phenomena of scratches of the northern parts of the United States are 
evidently all due to one general cause. 
The scratches in Ohio and Western New-York are generally in a west of north and east 
of south direction; and as there are there no topographical features of the country that are 
obvious reasons of the directions, we may refer to the general tendencies of the currents. It 
has been shown that the general tendency of the current from the south is towards the east; 
and this, meeting bodies moved by the northern current, would necessarily give to those bodies 
a new direction as the resultant of those forces ; or the currents themselves may be so blended 
as to give a new direction to both, and to bodies floated by them. In either case, the resul¬ 
tant of those forces (in which the floating body coming from a northwardly direction would be 
moved) would be to the eastward of south, depending for its direction upon the exact direction 
of the acting forces, and the relative amount of surface exposed to the action of each of them. 
This is believed sufl^icient to account for the directions of the scratches in Western New-York 
and Ohio, with some local exceptions, that may perhaps be dependent on local causes. Those 
of Wayne, Monroe and other counties, in a north-northeast and south-southwest direction, may 
be due to the action of the northern current through the St. Lawrence valley, and easterly 
trend of the other current through Lake Erie. 
The extension of the warm southwardly current* would tend to pass on eastwardly through 
the country of the north and south lakes of central New-York, and the Mohawk valley; while 
the underlying cold current from the north and from the northeast through the St. Lawrence 
valley, would press its drift southward upon the elevated lands on the south, and through the 
defiles into the present valleys of the tributaries of the Susquehannah and Allegany. 
In the valley of the Mohawk (which is south of the high mountainous primary nucleus of 
the northern part of the State), the easterly trend of the current from the south which we 
have traced, mingled more or less with the northern current, but uninfluenced in direction by it 
there, must have passed through the deep and broad valley of the Mohawk; and any scratches 
made by bodies floated by that current, must necessarily conform more or less nearly to that 
valley, except where there were lateral valleys to the south, through which materials drifted 
on the surface would necessarily float with these secondary currents to the south. Such 
effects in drift deposits, and smoothed and scratched rocks, with the scratches directed to 
the southward, are observed in the summits of all, or nearly all the north and south valleys 
leading from the Mohawk valley to the tributaries of the Delaware and Susquehannah, and 
fijpm Western New-York to the tributaries of the Susquehannah and Allegany. 
The main current, on emerging from the Mohawk valley, and meeting the current from the 
north flowing through the Champlain and Hudson valley, would have its direction changed 
♦ Perhaps a part of it may have passed through the St. Lawrence valley, but it is more probable that that valley was occupied 
by the northwardly currrent. 
