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 outcrops. 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 presents 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 preglacial 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. The broadest continuous area in the Still-Umpog Valley is, therefore, in the lower six miles between Brookfield and New Milford; south of that portion are several places where the valley is sharply constricted; and beyond the head of the Umpog, about one and a half miles below West Redding station (fig. 7), the Saugatuck Valley is a very narrow gorge. On the whole, the valleys south and southwest of Danbury are much narrower than the valley of the Still farther north. It is evident from these observations that Still River Valley is neither uniformly broad, nor does it increase in width toward the south.