One of the distinguishing features of Rocky River is the angle at
which it joins the Housatonic (fig. 1). The tributaries of a normal
drainage system enter their master stream at acute angles, an
arrangement which involves the least expenditure of energy. Rocky
River, however, enters the Housatonic against the course of the
latter, that is, the tributary points upstream. Still River and other
southern tributaries of the Housatonic exhibit the same feature, thus
producing a barbed drainage, which indicates that some factor
interfered with the normal development of tributary streams. Barbed
drainage generally results from the reversal of direction of the
master stream[6], but it is impossible to suppose that the Housatonic
was ever reversed. As will appear, it is an antecedent master stream
crossing the crystalline rocks of western Connecticut regardless of
structure, and its course obliquely across the strike accounts for
the peculiar orientation of its southern tributaries, which are
subsequent streams whose position is determined by the nature of the
rock. For the same reason, the northern tributaries of the Housatonic
present the usual relations.
[Footnote 6: Leverett, Frank, Glacial formations and drainage features
of the Erie and Ohio basins: U. S. Geol. Survey Mon. 41, pp. 88-91,
figs. 1 and 2, 1902. See, also, the Genoa, Watkins, Penn Yan, and
Naples (New York) topographic atlas sheets.]