s back on itself, the fall is 67 feet, or slightly
less than 5-1/2 feet to the mile (fig. 3, A).

[Illustration: ~Fig. 3.~ Profiles of present and preglacial Rocky River.
Elevations at a, b, c and i are from U. S. G. S. map.
Elevation at d is estimated from R. E. Dakin's records.
Elevations at e, f, g and h are from R. E. Dakin's records.
The U. S. G. S. figures for the same are enclosed in parenthesis.]

In tabular form the figures, taken from the Danbury and
New Milford atlas sheets and from reports of R. E. Dakin, are
as follows:

Miles Fall in feet per mile
Source to Sherman 4 177.5
Sherman to Wood Creek 8 6.25
Wood Creek to Jerusalem 4.5 3.8
Jerusalem to mouth 2.5 69.2

Near Jerusalem, where Rocky River makes its sudden change
in grade, there is an abrupt change in the form of the valley
from broad and flat-bottomed to narrow and V-shaped. The
profile of Rocky River is thus seen to be sharply contrasted with
that of a normal stream, which is characterised throughout its
course by a decreasing slope.

PREGLACIAL COURSE

The present profile of Rocky River and the singular manner in which
the lower course of the river is doubled back on the upper course are
believed to represent changes wrought by glaciation. Before the advent
of the glacier, Rocky River probably flowed southward through the
"Neversink-Danbury Valley," to be described later, and joined the
Still at Danbury, as shown in fig. 4. The profile of the stream at
this stage in its history is shown in fig. 3, B.

At Sherman a low col separates Rocky River basin from that of the
small northward flowing stream which enters the Housatonic about a
mile below Gaylordsville. Streams by headward erosion at both ends of
the belt of limestone and schist on which they are situated have
reduced this divide to an almost imperceptible swell. The rock
outcrops in the channel show that the glacier did not produce any
change in the divide by damming, though it may have lowered it by
scouring. Assume that at one time a divide also existed on the eastern
fork of Rocky River, for example near Jerusalem. According to this
hypothesis there was, north of this latter divide, a short northward
flowing branch of the Housatonic located on a belt of weak rock,
similar to the small stream which now flows northward from Sherman, and
very li