Topographical Features of the New Haven region. 55 



At the mouth of Pine-Marsh Creek, Mill River takes a bend a little 

 to the eastward of south, while the creek has a course as much to the 

 westward of south, and Mill Rock stands between the extremities of 

 the V thus made by the two channels. In this position of Mill Rock, 

 we find the explanation of the facts referred to. 



The great glacier having had its ploughing under-surface shaped by 

 the gap west of Mt. Carmel, through which Mill River passes, moved 

 southward, excavating the valley of Mill River, while, at the same 

 time, abrading the soft strata over the hills and plains. The Mill 

 Rock dike, making now a ridge 200 feet in height, stood in its path, 

 the brittle ice confronting the unyielding trap mountain. Under such 

 circumstances, it would have been a natural consequence that at some 

 point north, the brittle ploughshare should have divided, the smaller 

 part to pass toward the Whitney ville opening, by the east end of Mill 

 Rock, and make a shallow furrow because of the hard trap rock under 

 foot at the gap ; the larger part, encountering only the soft sandstone, 

 to plough out the deep broad valley of Pine-Marsh Creek, leading by 

 the west end of Mill Rock and almost directly toward the Beaver 

 Pond region. 



The question arises whether the excavation was continued into the 

 Beaver Pond basin and thence southward to tlie bay, or whether 

 there was a lifting of the ploughing portion of the glacier through 

 the elevating action of Mill Rock and merely a transfer of the exca- 

 vating pressure to a line more to the westward — the j:)rocess of trans- 

 fer producing the six or eight bays characterizing the eastern side of 

 the Beaver Pond depression and the broad southwesterly surface 

 channels which lead into them. In the former case. Mill River would 

 have run through the Beaver Pond excavation and West Creek ; in the 

 latter, the waters of Pine-Marsh Creek would always have been trib- 

 utary to Mill River in its present position ; for in the Glacial era they 

 would have been those of a sub-glacier stream, and these would have 

 become far moi'e abundant in flow during the melting of the glacier, 

 and thus have made a stream commensurate with the Pine-Marsh 

 Creek valley. 



There are three objections to the view that Mill River once dis- 

 charged itself through the Beaver Pond Meadows. (].) The Beaver 

 Pond depression is prolonged half a mile north of the point where the 

 Pine-Marsh valley makes its nearest approach to it, and this northern • 

 extremity does not bend toward the valley or show any inclination 

 that way. There is here evidence that the Beaver Pond excavation 

 had its own independent beginning. 



