Between Danbury and Beaver Brook Mountain the Still departs widely
from its former channel, as shown in fig. 6. At the foot of Liberty
Street in Danbury the river makes a sharp turn to the southeast, flows
through a flat plain, and for some distance follows the limestone
valley of the Umpog, meeting the latter stream in a swampy meadow. It
then cuts across the western end of Shelter Rock in a gorge-like
valley not over 200 feet wide. Outcrops of a gneissoid schist on the
valley sides and rapids in the stream bear witness to the youthfulness
of this portion of the river channel.
An open valley which extends from the foot of Liberty Street in a
northeasterly direction (the railroad follows it) marks the former
course of Still River, but after the stream was forced out of this
course and superimposed across the end of Shelter Rock by the
accumulation of drift in the central and northern parts of the valley,
it was unable to regain its old channel until near Beaver Brook
Mountain. The deposits of drift not only have kept the Still confined
to the eastern side of its valley but have forced a tributary from the
west to flow along the edge of the valley for a mile before it joins
its master stream.
About a mile north of Brookfield Junction, Still River valley begins
to narrow, and at Brookfield the river, here crowded to the extreme
eastern side, is cutting a gorge through limestone. The preglacial
course of the Still in the Brookfield region seems to have been near
the center of the valley where it was joined by Long Brook and other
short, direct streams draining the hillsides. The glacier, however,
left a thick blanket of drift in the middle of the valley which turned
the Still to the east over rock and forced Long Brook to flow for more
than a mile along the extreme western side of the valley.
[Illustration: ~Fig. 9.~ Early stage of the Rocky-Still River,
antedating preglacial course shown in figure 4.]
The broad valley through which the Still flows in the lower part of
its course extends northward beyond it for over two miles, bordering
the Housatonic River. At Lanesville near the mouth of the Still, the
river has cut a gorge 30 feet deep and one-quarter mile long in the
limestone. Upstream from this gorge the river meanders widely in a
flat valley, whereas on the downstream side it has cut a deep channel
in the drift in order to reach the level of the Housatonic. There is
room in the drift-covered plain to the west for a buried channel of
Still River which could join the Housatonic at any point between New
Milford and Stillriver station. If the depth of the drift be taken at
25 feet, there would seem to be no objection to the supposition that
the Still initially joined its master stream opposite New Milford, as
shown in fig 6. After the limestone had been worn down to approximate
baselevel, the tendency of the Still would have been to seek an outlet
farther south in order to shorten its course and reach a lower level
on the Housatonic. This stage in the evolution of the river may not
have been reached before the ice age, and it is thus possible that
glacial deposits may have pushed the river to the extreme southern
side of its valley, superimposed it over rock, and forced it to cut
its way down to grade.