24 A. P. BRIGHAM — GLACIAL FLOOD DEPOSITS. 



jacent Oriskany creek and about the same distance above the surface of 

 a smaller pond with surface outflow near by. Into the latter it doubt- 

 less pours its surplus water through the intervening gravel. South of 

 the lake the continuity of the plain is much broken, and we have deep 

 and broad kettles and kames rising to, but not surmounting, the general 

 level. 



The material is course and bouldery in character and tumultuous in 

 structure near the moraine, but surfaces are sufficiently worn by rolling 

 to remove all glacial graving. Farther forward, sand and gravel replace 

 the coarser matter and assume a definite structure. A well drilled 113 

 feet from the top of the northern terrace near the moraine found gravel 

 and boulders to a depth of 75 feet, and sand from that point to the bot- 

 tom. On the north margin of the south terrace exposures of the lower 

 beds are frequent for more than a half mile. Fresh sections are so nu- 

 merous as to demonstrate that the " foreset beds," as termed by Professor 

 Davis, have unbroken continuity for 1,230 feet, well stratified sand and 

 medium gravel beds inclining forward from 25 to 30 degrees. These 

 beds, with the pronounced frontal slopes and lobes at Bouckville, appear 

 to prove 'the existence of a water body into which the material was dis- 

 charged, at least during the later stages of construction. The lake may 

 have been marginal to a shrinking ice-tongue merely, or may have been 

 more extended, filling the valley and prolonged southward. It has 

 seemed possible to account for such a temporary lake by the stagnation 

 and recession of the ice in this diagonal valley and the persistence of a 

 strong current from the more direct Oneida valley acting as a dam at 

 Pecksport. 



Additional accumulations of this order lie between Pecksport and 

 Hamilton, a deep glacial lake occupying most of the interval between the 

 terraces. The easterly one is three-fourths by one-fourth of a mile in 

 extent, 27 feet high at the south end, rising to 35 feet farther north. The 

 surface is smooth, slopes slightly southward, but more rapidly toward 

 the axis of the valley. The south end is strikingly lobate, with frontal 

 slopes of 13 to 18 degrees. The material of the lobes is sand and gravel, 

 rather fine. Northward we have abundant small boulders, gravel, and 

 sand, one fresh section, coarsely stratified, showing southward inclination 

 of 10 to 15 degrees. 



The western terrace accords with the other in height and slope, is 

 broader and longer, ends southward in no very characteristic way, and 

 is somewhat interrupted by transverse depressions. It thus fails of the 

 delta character shown by its companion, but is headed by a moderate 

 assemblage of kames, which, in turn, the easterly terrace lacks. Be- 

 tween the kames and the terrace runs the foss often found in such situ- 

 ations. 



