Topographical Features of the N^ew Haven region. 51 



great depths,* and less deeply the harder rocks, and in dislodging mass- 

 es from the dikes and other rock formations which had hecn previously 

 loosened in any way, the masses sometimes many tons in weight ; third- 

 ly, the taking up of the sand or gravel, stones and rocks, thus separated 

 or dislodged, into its own mass, which it was enabled to do because of 

 the attendant breaking up of the ice just alluded to, and the readi- 

 ness with which ice becomes solid again by regelation after a short 

 rest. Thus the glacier moved slowly on, engorging itself with what- 

 ever loose material it made, as well as with what it found in its path. 

 The glacier was made ready for its great work of abrasion eHher in 

 the way of rasping, planing, channeling or ploughing through the 

 sand, stones and rocks with which it was shod. The hard granite 

 rocks east of New Haven, as is exhibited at Stoney Creek, were mark- 

 ed by the glacier not only with scratches but with broad furrows six 

 inches to a foot in depth ; and this in addition to an unknown amount 

 of planing above the present surface. The soft red sandstone of the 

 region easily yielded under the pressure, and was ground up and 

 ploughed out in some places to a depth of several hundred feet, the 

 material being absorbed at the same time into the icy mass. Hills 

 and ridges lost much of their height, and those of trap were exten- 

 sively stripped of their associated sandstone. The isolated East Rock, 

 lying north and south, or in the direction of the movement, between 

 the Mill River valley and that of the Quinnipiac, was abraded both 

 along its western front and on the rear, and left nearly bare of sand- 

 stone on both sides. Pine Rock, an east and west ridge, besides un- 

 dergoing an unknown amount of decapitation, lost the sandstone on 

 its northern side for the upper sixty feet, and a wall of trap of this 

 height is left bare. Mill Rock suifered a like fate with Pine Rock ; 

 for the north wall of the trap dike projects in places twenty or twen- 

 ty-five feet above the sandstone. . Whitney Peak is in like manner 

 bare of sandstone on its north side for forty feet from the summit. 

 At the Fair Haven sandstone quarries and over the country near the 



* While this sandstone is hard enough for an excellent building stone m some por- 

 tions of the Connecticut valley, and often very hard-baked in the vicinity of the trap 

 dikes, a large portion of that exposed to view over the ISTew Haven region a little 

 remote from the trap is so soft that it is easOy dug up by a pick, and sometimes even 

 by an ordinary shovel; so that we have reason for regarding the strata of it underly- 

 ing the most of the New Haven plain, or its alluvium, as of this soft kind. Part at 

 least of the hardening and reddening of the sandstone was evidently due, as stated 

 above, to the heat that escaped in connection with the trap eruptions and from fissures 

 opened in their vicinity ; and in regions where there was no heat from these sources 

 the rock was but little hardened. 



