No. 3O.] STILL RIVER. 33 



The 'broadest continuous area in the Still-Umpog Valley is, 

 therefore, in the lower six miles between Brookfield and New 

 Milford; south of that portion are several places where the 

 valley is sharply constricted ; and beyond the head of the Umpog, 

 about one and a half miles below West Redding station (fig. 7), 

 the Saugatuck Valley is a very narrow gorge. On the whole, 

 the valleys south and southwest of Danbury are much narrower 

 than the valley of the Still farther north. It is evident from 

 these observations that Still River Valley is neither uniformly 

 broad, nor does it increase in width toward the south. 



But if a broad valley is to be accepted as evidence of the work 

 of a large river, then there is too much evidence in the Still 

 River valley. The broad areas named above are more or less 

 isolated lowlands, some of them quite out of the main line of 

 drainage, and can not be grouped to form a continuous valley. 

 They can not be attributed to the Housatonic nor wholly to the 

 work of the insignificant streams now draining them. These 

 broad expanses are, in fact, local peneplains developed on areas 

 of soluble limestone. The rock has dissolved and the plain so 

 produced has been made more nearly level by a coating of peat 

 and glacial sand. In a region of level and undisturbed strata, 

 such as the Ohio or Mississippi Valley, a constant relation 

 may exist between the size of a stream and the valley made by 

 it; but in a region of complicated geologic structure, such as 

 western Connecticut, where rocks differ widely in their re- 

 sistance to erosion, the same result is not to be expected. In this 

 region the valleys are commonly developed on limestone and their 

 width is closely controlled by the width of the belt of limestone. 

 Even the narrow valleys in the upland southwest of Danbury are 

 to be accounted for by the presence of thin lenses of limestone 

 embedded in gneiss 'and schist. 



The opinion of Hobbs that Still River valley is too wide to be 

 the work of the present stream takes into consideration only the 

 broad places, but when the narrow places are considered it may 

 'be said as well that the valley is too narrow to be the work of a 

 stream larger than the one now occupying it. Valley width has 

 only negative value in interpreting the history of Still River. 



