ain, and those flowing over limestone or schist
deepened, then widened their valleys much faster than could the
streams which flowed over the resistant granite and gneiss. By a
system of stream piracy and shifting, similar to that which has taken
place throughout the Newer Appalachians, the smaller streams in time
became well adjusted to the structure. They are of the class called
subsequents; on the other hand, the Housatonic, which dates at least
from the beginning of the uplift if not from the earlier period of
peneplanation, is an antecedent stream.

The complex rock surface of western Connecticut had reached a stage of
mature dissection when the region was invaded by glaciers.[4] The ice
sheet scraped off and redistributed the mantle of decayed rock which
covered the surface and in places gouged out the bedrock. The
resulting changes were of a minor order, for the main features of the
landscape and the principal drainage lines were the same in preglacial
time as they are today. It is thus seen that the history of the
smaller streams like those considered in this report involves three
factors: (1) the normal tendencies of stream development, (2) the
influence of geologic structure, and (3) the effect of glaciation.

The cover of glacial deposits is generally thin, but marked
variations exist. The fields are overspread with coarse till
containing pebbles 6 inches in diameter to huge boulders of 12 feet or
more. The abundance, size, and composition of the boulders in the till
of a given locality is well represented by the stone fences which
border fields.

[Footnote 4: This stage of glaciation is presumably Wisconsin. No
definite indication of any older glacial deposits was found.]

[Illustration: ~Fig. 1.~ Present drainage of the Danbury region.]

The regional depression which marked the close of the glacial period
slackened the speed of many rivers and caused them to deposit great
quantities of modified or assorted drift. Since glacial time, these
deposits have been dissected and formed into the terraces which are
characteristic of the rivers of the region. A form of terrace even
more common than the river-made terrace is the kame terrace found
along borders of the lowlands. Eskers in the Danbury region have not
the elongated snake-like form by which they are distinguished in some
parts of the country, notably Maine; on the contrary, they are
characteristically short and broad, many having numerous bra