The conclusion that the Still-Umpog was not reversed by a glacial dam does not preclude the possibility that this valley has been occupied by a south-flowing stream. It is probable that in an early stage in the development of the drainage, the streams of the Danbury region reached Long Island Sound by way of the Still-Umpog-Saugatuck valley. Along this route, as described under the heading "The Still-Saugatuck Divide," is a fairly broad continuous valley at a higher level than the beds of the present rivers. A south-flowing river, as shown in fig. 9, brings all the drainage between Danbury and the Housatonic into normal relations. This early relationship of the streams was disturbed by the reversal of the waters of the ancient Still in the natural development of a subsequent drainage. The Housatonic lowered the northern end of the limestone belt, in the region between New Milford and Stillriver village, faster than the smaller south-flowing stream was able to erode its bed. Eventually a small tributary of the Housatonic captured the headwaters of the south-flowing river, and by the time the latter had been reversed as far south as the present divide at Umpog Swamp, it is probable that the advantage gained by the more rapid erosion of the Housatonic was offset by the Saugatuck's shorter course to the sea. As a result the divide between Still and Saugatuck Rivers at Umpog Swamp had become practically stationary before the advent of the glacier. The complex history of Still River is not fully shown in the stream profile, for the latter is nearly normal, except in the rock basins in the valley of the Umpog. This is due to the fact that changes in the course of the Still, caused by the development of a subsequent drainage through differential erosion, were made so long ago that evidence of them has been largely destroyed. The foregoing conclusion practically eliminates hypothesis IV--that the Still developed from the beginning as a subsequent stream in the direction in which it now flows. This hypothesis holds good only for the short portion of the lower course of the present river, that is, the part representing the short tributary of the Housatonic which captured and reversed the original Still. DEPARTURES OF STILL RIVER FROM ITS PREGLACIAL CHANNEL 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.