14 NEW YORK STATE MUSEUM 



to the Mohawk river at Northwestern. The history of the lake is 

 graphically indicated in plates 15 and 16 and the central part of the 

 basin is shown in plate 3. The lake was narrow at the south end, 

 being- about two miles wide at Port Leyden, three miles at Lyons 

 Falls, five miles at Glenfield and expanding northward. The west 

 shore of the lake was quite direct, lying along the limestone slope, 

 but the east shore was very irregular, being formed by the enlarging- 

 deltas built by the Adirondack drainage. The depth of the lake was 

 about 260 feet at Port Leyden, 300 feet at Lyons Falls and 400 feet 

 at Glenfield. 



The outlet valley is a narrow, deep channel in shale, evidently cut 

 by a vigorous stream of relatively short life, and well shown in 

 plate 2. It does not appear just where the initial overflow began, 

 but we know that it could not have been higher than 1240 feet, the 

 altitude of the deserted Remsen outlet. Before the Lansing kill 

 valley became the outlet of Black waters it must have been flooded 

 by the Forestport lake, until the ice front receded from the Steuben 

 valley between Trenton and Northwestern (see page 35). The ulti- 

 mate head of the glacial river and the present col is a flat stretch 

 extending southeastward from Boonville about two miles and now 

 occupied by the summit level of the Black river canal. This has one 

 lock (no. 71) in Boonville and the next (no. 70) over two miles 

 south, the water surface being 1120 feet. About one and one-half 

 miles south of the village the canal has a cut of 10 feet in limestone, 

 which makes the present altitude of the outlet channel about 1130 

 feet. Immediately below the head of the channel the river had 

 cascades, the widened main channel having narrow and steep 

 trenches on both sides, with a plunge basin and lakelet on the east 

 side. 



One mile below the cascades the channel becomes very narrow, 

 in shale, with only room for the present creek, the highway and the 

 canal, and so continues for six miles. The succeeding five miles to 

 Northwestern have a somewhat wider but yet narrow valley, and 

 from that village the valley is open, preglacial, and partly filled with 

 detritus. Below the village of Delta the ancient valley was blocked 

 with moraine and the present Mohawk has been compelled to cut a 

 channel on the east side of the old valley, locally known as the 

 "' Palisades." Delta village lies on the old lake bottom and present 

 Mohawk flood plain. 



From the channel head two miles below Boonville, to North- 

 western, a distance of about 11 miles, the channel bottom drops 530 

 feet (from 1130 to 600), the canal having in that stretch 48 locks. 



