192 &RIGHAM—TOPOGRAPHY AND DEPOSITS OF MOHAWK VALLEY. 
Herkimer. Once discharged into the Mohawk valley at Rome and Oris- 
kany, the gravels were spread eastward by the great currents flowing out 
by the Mohawk valley. 
MATURING OF THE LOWER MOHAWK VALLEY 
As described by Vanuxem, and in greater detail by Darton,* a series 
of faults crosses the river between Little Falls and Hoffmans. The 
uplict in each case is on the west, and to a greater or less degree the 
gneiss, the Calciferous, and Trenton are brought up within the reach of 
the valley-making agencies. It would be difficult to find a more in- — 
structive example of the effect of hard rocks in retarding the maturing of — 
_a valley. But for the faults the lower Mohawk should be as broad and 
well developed as the upper valley, unless indeed the western Mohawk 
glacier was more effective in excavation. 
Three of the dislocations have especially influenced the topography. 
At Hoffmans no gneiss exposed is to be seen, but the Calciferous and 
Trenton appear for several miles, with noteworthy bluffs of Calciferous, 
and the valley bottom is but a scant fourth of a mile in width. The 
valley is still more immature at the Noses, both because it is farther up- 
stream and because a greater thickness of hard rocks is encountered. 
The whole thickness of the Calciferous is exposed, and of the gneiss, ac- 
cording to Darton, 40 feet on the south side and 70 feet on the north. 
Strong bluffs run for several miles, attaining a height of 500 feet toward 
the fault, and facing the river with many slopes of 40 to 60 degrees, rising 
in places to the vertical. The cliff runs northward for some miles, and 
to the east the valley becomes at once broad and well matured. The 
topographic effects at Little Falls are sufficiently well known, and in 
general it may be said that but for the series of faults the Hudson’s ad- 
vantage should have anciently given it the country as far west as Syracuse. 
Part of the area which it lost for structural reasons it has gained by 
means of glaciation. It should be added that from Little Falls to Hoff- 
mans the river flows approximately on a rock bottom. The hard rock 
barriers have not been breached to any extent below the level of the 
stream, though it is possible that minor rock basins lie between them. 
Rock is exposed in the bed of the river at the state dam, 5 miles below 
Little Falls; also on the edge of the floodplain at Indian Castle. At Saint 
Johnsville rock lies at a depth of 14 feet by the edge of the river. From 
Saint Johnsville to Palatine Bridge on the north side drift is scanty, ex- 
posures of rock being frequent and often continuous along the lower 
slopes. At Canajoharie and the Noses rock appears at the edge of the 
*N. H. Darton: A preliminary description of the faulted region of Herkimer, Fulton, Montgom- 
ery, and Saratoga counties. State Museum Report, vol. 2, no, 48, 1896, 
