Topographical Features of the Neio Haven region. 57 



the southern extremity of the Rock, and so have swept away the sand- 

 stone there remaining. 



The great ghieier did not succeed in ploughing out the Mill Rock 

 dike at the Whitney ville notch helow the level of the bottom of the 

 present dam, for the dam is built on the solid trap dike. The ice must 

 therefore have plunged down the front of it (the land having been 

 higher than now), and with it the sub-glacial stream descended. 

 South of this it appears to have made a deep Mill River channel. 



The glacier acted like the moulding tool in the plough of the car- 

 penter.. But the convexities and concavities on the cutting or abrading 

 edge of the tool were not needed in the pliant material ; for by the 

 fenders placed in its front, in Pine Rock, Mill Rock, and East Rock, the 

 edge was made in these parts to rise or arch upward, and by this 

 means long ridges of various heights were made beween the furrows. 



The correspondence between the channeling of the plain and the 

 position of the trap ridges is so close (especially if it is considered 

 to what an extent subsequent river and marine action must have 

 tended to modify the features of the surface and obliterate the tracks 

 of the glacier) that there seems to be here visible demonstration of 

 glacier action, and of the insufficiency of the iceberg theory of the 

 drift. 



If Sachem's ridge, the Beaver Hills and Pine Hill were the only 

 examples of north-and-south sandstone elevations due to hard-rock 

 fenders, the correctness of the explanation offered might be reasona- 

 bly questioned. But they are the least remarkable instances. Over 

 Hamden there are three north-and-south ranges three to four miles long, 

 as exhibited on the map, and they may be distinctly followed northward 

 to elevations in the transverse range of heights west of Mt. Carmel. 

 Cherry Hill (Ch) is the termination of one of these lines. A still 

 more striking example is the Quinnipiac ridge, the dividing ridge be- 

 tween Mill River valley and the Quinnipiac. It stretches from the 

 south side of Mt. Carmel to Whitney Peak, a distance of six miles, 

 and while broad and broken into hills to the north, is to the south 

 an evenly rounded elevation, looking from the summit of Mt. 

 Carmel like a splendid example of landscape grading. According 

 to the theory jiresented, this long ridge of sandstone owes its ex- 

 istence to the arching upward of the ice by the high east-and-west Mt. 

 Carmel range, the ridge being apart of the great sandstone formation 

 left thus elevated in consequence of this arching. The arch, although 

 narrowing somewhat, did not flatten out before reaching Wliitney 

 Peak, as the continuation of the ridge shows ; and here it was raised 



