200  BRIGHAM—TOPOGRAPHY AND DEPOSITS OF MOHAWK VALLEY. 
Mohawk valley northward for a mile or more. These levels range from 
490 feet to slightly above 600 feet. South of Herkimer, across the valley, 
les the frontal portion of the delta. It may have been built at the front 
of an ice lobe pushing across the main valley, or may have been largely 
cut away byrivererosion. At its north edge by the canal 10 feet of fine, 
black, tough, lacustrine clay are overlain by 15 feet of very coarse gravel. 
The apron terminates short of the south side of the valley, leaving a de- 
pression through which the West Shore railway passes. The gravels 
have been extensively excavated for ballast, and are rather fine and in 
beds inclining southward. Position, contours, and structure are demon- 
strative of their origin. 2 
Deposits about Little Falls—A massive shoulder of drift continues on — 
the south side to a point near Little Falls, going east. The clays and fine 
sands give way to ordinary kame gravels and contours. At the north- 
west of Little Falls a very strong embankment of drift appears, consisting 
of till below and sands and gravels above. The mass is kame-like above 
the town, but a solid shoulder to the west, where its altitude is 808 feet 
above tide by the aneroid. The escarpment on the south border of the 
shoulder is steep and gashed by deep erosion gorges alternating with 
sharp spurs. 
It will have been seen from the detailed account of beds between 
Utica and Little Falls that a generalized section of the marginal drift 
from the top downwards will stand as follows: 
Till, overlying undisturbed beds of sand and grayel........ 10-12 feet. 
Fine to coarse sands;and oravelss 0. 22.202. encis esse esses A yariable thickness. 
Waterlaid, fine clays with glaciated pebbles............... A few to 36 feet. 
No till appears west of Utica and no fine clays, except below the val- 
ley bottom, though the sands and silts are very fine. 
Discussion of levels and succession of events—The altitudes of the several 
deposits thus far described fall into fair accord. 
Feet. 
Head of Rome-Westernville delta, about...... 575 
Nimes MulerGneekydeliahe-eeseerecremas ice 600 to 520 
Oriskany-Whitestown terrace..........-....- 540 
JarEhaaroray (GME) osqocpss6> denon ecoseeoe soe 560 to 480 
aon (delta) ci ace eicteemaa deeeoe ere stare elas 600 to 480 
West Canada Creek delta.:..-........-.-...- 600 to 490 
These figures indicate a waterlevel at about 600 feet.* The lower 
limits of height represent offshore delta deposits. If the accordance of 
* Professor Davis has called the attention of the writer toa sandplain at Oneida castle whose 
altitude requires a controlling barrier at not far from 600 feet, See also D. F. Lincoln: Geology of 
Seneca county, New York. State Museum Report, vol. 2, no. 48, 1894, p. 77. 
