It is concluded, therefore, that the Housatonic between Bulls' Bridge and Derby ([fig. 10]), had its course determined by the slope of the uplifted peneplain and is antecedent in origin. The old headwaters extended northwest from the turn in the river near Bull's Bridge, whereas that part of the river above Bull's Bridge was initially a minor tributary. This tributary, because of its favorable situation, in time captured all the drainage of the extensive limestone belt to the north and then became part of the main stream. The lower Housatonic, therefore, has always maintained its ancient course diagonal to the strike of formations, and differential erosion, which reaches its maximum expression in limestone areas, is responsible for the impression that the Still River lowland and other valleys west of the Housatonic may once have been occupied by the latter stream.
[12] Hobbs, W. H., Still rivers of western Connecticut: Bull. Geol. Soc. Am., vol. 13, p. 25, 1901.
[13] Crosby, W. O., Notes on the geology of the sites of the proposed dams in the valleys of the Housatonic and Ten Mile rivers: Tech. Quart., vol. 13, p. 120, 1900.
| State Geol. Nat. Hist. Survey | Bull. 30. Plate IV. | |
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A. View down the Housatonic Valley from a point one-half mile below Still River station. Pumpkin Hill, a ridge of resistant schist and quartzite, stands on right. A small island lies in the river.
B. Part of the morainal ridge north of Danbury. Till capped by stratified drift one mile north of Shelter Rock.