4O CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



North of Bethel the Umpog occupies an open valley developed 

 in limestone. Knolls of limestone rise to heights of about 40 

 feet above the floor of the valley and their upper surfaces are 

 cut across the highly tilted beds. This truncation, together with 

 a general correspondence in height, suggests that these knolls, 

 as well as the rock terraces found between Bethel and West 

 Redding, and the limestone ridge which forms the divide itself, 

 are portions of what was once a more continuous terrace pro- 

 duced by stream erosion and that they determine a former river 

 level. The absence of accurate elevations and the probability of 

 glacial scour make conclusions regarding the direction of slope 

 of this dissected rock terrace somewhat uncertain. As will be 

 indicated later, however, it seems likely that these terrace 

 remnants mark the course of a southward flowing river that 

 existed in a very early stage in the development of the drainage. 



South of Bethel the old Umpog valley has lost from one-third 

 to one-half its width through deposits of stratified drift (PI. II, 

 A and B). On the west, gravel beds lie against rock and till; 

 on the east, deposits of sand and coarse gravel form a bench or 

 terrace from 500 to 700 feet broad, which after following the side 

 of the valley for one-half mile, crosses it diagonally and joins the 

 western slope as a row of rounded hills. Through this drift 

 the present stream has cut a narrow channel. 



The narrowest part of the Umpog valley is about one mile 

 south of Bethel. Farther upstream the valley expands into the 

 flat occupied by Umpog Swamp, which presents several interest- 

 ing features. The eastern, southern, and western sides of the 

 swamp are formed of irregular masses of limestone and granite- 

 gneiss 20 to 60 feet high. Near the northwestern edge of the 

 swamp is a terrace-like surface cut on limestone. Its elevation 

 is about the same as that of the beveled rock remnants lying in 

 Umpog valley north of Bethel. 



Umpog Swamp was formerly a lake but is now nearly filled 

 with organic matter so that only a small remnant of the old 

 water body remains. Soundings have revealed no bottom at 

 43 feet 1 and the depth to rock bottom is not less than 45 feet. 

 The swamp situated one-half mile southwest of Bethel has a depth 

 to rock of 35 feet. In their relation to the Still River system 



'Report by T. T. Giffen, 1907. 



