32 



SURFACE GEOLOGY. 



W 



The village of Haverhill is situated on a high, smoothly rounded, ter- 

 race-like area of till. This slopes steeply towards the river, but very 

 slightly to the north and north-east, and extends nearly level for half a 

 mile south-east to the foot of Catamount hill, and for two miles south- 

 ward along the Piermont road. A large proportion of the boulders in 

 this till are glaciated, sometimes jDreserving distinct striae. Tlie prevail- 

 ing size is less than three feet ; but rocks of five or six feet diameter, or 

 even larger, also occur. These are found most rarely over the south part 

 of this area in Piermont, where the abundant rounded or glaciated peb- 

 bles exposed by the channels of streams present the appearance of coarse 

 . rt kame-like gravel. At about one fourth mile south- 

 west from Haverhill village a gully recently made on 

 a previously smooth slope, at a height about 175 feet 

 ^ above the river, and consequently much above its 

 S highest terrace, and 75 feet below the village, showed 

 ", 1 5 feet of modified drift resting on till. The surface 

 "5) was 3 feet of coarse gravel, which was succeeded by 

 J 1 2 feet of interstratified fine gravel and sand, oblique- 

 H ly bedded. The stratification here sloped with the 

 2 present surface, about 10 feet in 100, with the ob- 

 H liquely bedded portions steeper in the same direc- 

 Q tion. Similar sections of overlying modified drift are 

 Q shown in many places west and south from Haver- 

 o hill, but the north and east parts of this area consist 

 < only of till. This is the ground-moraine of the ice- 

 sheet, peculiarly massed here in very large amount, 



^ resembling the massive rounded hills of the same 



d 



H material, which are abundant near the coast. On the 



w opposite side of the river we find the extensive slope, 

 tA which rises south from Hall's brook, also composed 

 •I-" of till with no outcropping ledges. 



In Piermont, opposite Bradford village, the modi- 

 fied drift is divided by Icdgy hills close to the river 

 ?: into two belts, the eastern of which has a height of 



478 feet above the sea, or about 90 above the river, where it departs 

 from the main valley. This extends along 'Gully brook, sloping in two 



•88^ -a 



