32 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



2. Tributary valleys pointing upstream with respect to the 

 present river. 



3. The regional slope not in accord with the present course 

 of the river. 



4. Extensive glacial filling and ponded waters in the region 

 of the present sources of Still River. 



5. Strong glacial scouring at the northern end in default of 

 a glacial dam at the southern end of the valley, or to assist a dam 

 in its work of reversing the river. The evidence of glacial 

 erosion would be a U-shaped valley, overdeepening of the main 

 valley, and tributaries ungraded with respect to the main stream. 



1. A VALLEY WIDE THROUGHOUT OR BROADENING 

 TOWARD THE SOUTH 



At the mouth of Still River and for several miles north and 

 south of it there is a plain more than a mile broad. This plain 

 continues southward with a width of about one-half mile until, 

 at Brookfield, it is interrupted by ledges of bare rock. A little 

 distance south of Brookfield the valley broadens again to one-half 

 mile, and this width is retained with some variation as far as 

 Danbury. Drift deposits along the border of the valley make it 

 appear narrower in some places than is indicated by rock out- 

 crops. Between Brookfield and Danbury the narrowest place in 

 the valley is southwest of Beaver Brook Mountain, where the 

 distance between the hills of rock bounding the valley is one-fifth 

 of a mile (fig. 6). Opposite Beaver Brook Mountain, which pre- 

 sents vertical faces of granite-gneiss toward the valley, is a hill of 

 limestone. Ice, crowding through this narrow place in the valley, 

 must have torn masses of rock from the side walls, so that the 

 valley is now broader than in preglacial time. The constrictions 

 in the valley near Shelter Rock, are due to the fact that the pre- 

 glacial valley, now partly buried in till, lies to the north. There 

 are stretches of broad floor in the valley of Beaver Brook, in the 

 lower valley of Umpog Creek, in the fields at the south end of 

 Main Street in Danbury, about Lake Kanosha, and where the 

 Danbury Fair Grounds are situated. In the western part of 

 Danbury, however, and at Mill Plain the valley is very narrow, 

 and at the head of Sugar Hollow, the valley lying east of Spruce 

 Mountain, is a narrow col. 



