Drainage modifications and glaciation in Drainage modifications and glaciation in the Danbury region, Connecticut drainagemodifica00harv Year: 1920 No. 30.] STILL RIVER. 41 these two swamps may be regarded simply as extensions of the Umpog Creek channel, but when the elevations of their bottoms are compared with that of points to the north and south, where the river flows on rock, it will be seen that a profile results which is entirely out of harmony with the present profile of the river. Thus Umpog Creek falls 40 feet at the point where it spills over the rock ledge into the swamp, and if
Drainage modifications and glaciation in Drainage modifications and glaciation in the Danbury region, Connecticut drainagemodifica00harv Year: 1920 No. 30.] STILL RIVER. 41 these two swamps may be regarded simply as extensions of the Umpog Creek channel, but when the elevations of their bottoms are compared with that of points to the north and south, where the river flows on rock, it will be seen that a profile results which is entirely out of harmony with the present profile of the river. Thus Umpog Creek falls 40 feet at the point where it spills over the rock ledge into the swamp, and if the 45 feet which measures the depth of Umpog Swamp be added, the difference in level is seen to be at least 85 feet. A similar calculation locates the bottom of the smaller swamp near Bethel at an elevation of 340 feet above sea-level or on the same level as the bottom of Umpog Swamp. In a straight line 2j4 miles north of Bethel, Still River crosses rock at a level of 350 feet, or 10 feet higher than the bottom of Umpog Swamp. At Brookfield, 6y2 miles north of the mouth of the Umpog, the Still crosses rock at 260 feet, and 4^2 miles farther north, it joins the Housatonic on a rock floor 200 feet above sea-level (fig. 8, A). Such a profile can be ex- Fig. 8. Profiles of rivers. A. Profile of present Still River and buried channel of Umpog-Still River. \\. Profile of preglacial Croton-Still River. C. Profile of preglacial Umpog-Still River. Solid lines show the present levels. Dotted lines show preglacial levels. plained in either of two ways: glaciers gouged out rock basins in the weak limestone, or the river in its lower part has been
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