FLOOD GRAVELS OF THE LOWER MOHAWK VALLEY. 207 
may have been filled, but later opened and their edges rimmed out by 
the stream. 
It is not in the plan of this paper to discuss the delta of the lower 
Mohawk. The character and extension of the deposits which belong to 
it and their relations to the other Pleistocene materials of the Hudson 
valley offer an adequate field for a separate investigation. 
Various flood gravels.—Various gravels along the valley receive brief 
reference. Hast of the Little Falls gorge is the small moraine described 
by Chamberlin and south of it along the valley side a somewhat morainic 
accumulation, not sufficiently observed to warrant a detailed notice. 
Large boulders of gneiss are associated with coarse gravels, a natural 
product of the vigorous glacial and aqueous erosion of the gneissic 
barrier to the west. 
From Hast creek to near Saint Johnsville there extends for two miles 
a somewhat uneven terrace of coarse, indurated, horizontally bedded 
eravels, from 40 to 60 feet high. Its origin is not clear. It may be a 
remnant of a much more extensive sheet of gravel, as there are indica- 
tions of terracing upon the erosion cliff along its southern border. It 
may be derived from the East Creek valley. The plentiful exposures of 
limestone in that valley, taken with the extensive induration of the 
gravel seen where the Central railway has excavated for ballast, empha- 
sizes this suggestion. 
A very interesting gravel bed runs from the big Nose on the north side 
past Yosts station. It is three-quarters of a mile long and has been 
opened for nearly its entire length for the railway and to the depths of 
_ from 5 to 20 feet. The valley bottom abruptly widens from a quarter of 
a mile at the Noses to nearly three-quarters of a mile here, though the 
Calciferous cliffs still rise on the north. The railway runs between the 
gravel bed and the river, whose flood waters never now quite reach the 
track. Except at the west end, where it is a few feet higher, the gravel 
rises about 8 feet above the present floodplain. The material is fine, 
very uniform, with asandy matrix, and pebbles rarely exceeding an inch 
in diameter. The gravel is so clean to the top as to support only a spare 
growth of weeds. Along the north border the surface slopes gently 
toward the base of the cliff. Fresh exposures by the steam shovel show 
the same inclination of the strata. A long and very fine exposure near 
the middle of the mass shows the beds inclining down theriver from 8 to 
4 degrees, with elaborate displays of cross-bedding. The whole appears 
to be an alluvial apron made by the flooded Mohawk. As the pent up 
stream emerged from the narrow channel between the shores it dropped 
its well worn burden into the more quiet waters below, waters which 
XXXI—Butt. Groz. Soc. Am., Von. 9, 1897 
