GLACIAL WATERS IN BLACK AND MOHAWK VALLEYS 3 1 



to 720, belong to the Amsterdam lake ; below about 780 they belong 

 to the Sacandaga tributary lake. All the above figures are from the 

 map contours. 



In the narrow Mohawk valley the lowest levels are the most 

 prominent, being the accumulations of detritus by downwashing 

 into the bottom of the valley and leveling by the later waters. These 

 plains include all the level stretches which are so conspicuous from 

 the railroads in the valley. Following are some of the occurrences: 

 at Oriskany, both sides of the valley, at 520-540; Frankfort, 500; 

 Ilion, 500; Herkimer, 520; Fonda, 420-460; Tribes Hill, 420-440; 

 Amsterdam, 420-440; near the mouth of Schoharie creek from 

 420 down. The most extensive plains lie north of Rome (plate 2), 

 built by the heavy ice-border drainage along the north side of the 

 ice lobe, at 600 down to 460 feet. 



The occurrence of the lake plains in the Sacandaga valley and the 

 lower Mohawk have been noted by Professor Brigham, and correctly 

 attributed to a Mohawk lake, but without determination of the out- 

 let channel (see title 6, pages 26-28). 



FIFTH stage: lake ALBANY 



The name Lake Albany has been given by Professor Woodworth 

 to the body of water held in the Hudson valley in the Albany region 

 in which were deposited the widespread sands and clays, partly 

 shown in plate 6. This lake and its relations are described in 

 State Museum Bulletin 84 (see title 40), and it is not the province 

 of the present writing seriously to discuss the Hudson-Champlain 

 lake history. Woodworth regards the Albany waters as lying against 

 the receding ice front northward over the Fort Edward district 

 as far as Fort Ann, and as extending south in a narrowing strip of 

 water probably to Kingston. He supposed that the barrier on the 

 south was due to elevation of the lower Hudson a few hundred feet 

 above its present level, with probably some obstruction by morainal 

 drift in the gorge of the highlands. The final draining of the lake 

 he suggests might have been due to the removal of the drift barrier 

 by the greatly increased volume of water when all the overflow of- 

 the Great Lakes was turned through the Mohawk valley, in Iroquois 

 time. 



The broad plains at South Schenectady, which we may consider 

 the head of the Albany delta plains, are 340 feet elevation. Some- 

 what interrupted by glacial drift the lake plane steadily declines 

 until at South Bethlehem, near the bottom of plate 6, it is 200 feet; 

 and at Coeymans the deposits terminate at 160 feet. 



