AEEAL DESCRirTIOX 619 



heaviest load of detritus, especially that of the Farniiiigton Eiver, was 

 drifted southward. The delta of the Pequabuck liiver in the highest 

 water was built at the edge of the highland southeast of Bristol. This 

 splendid delta, with altitude 240 feet, carriers the head of Eightmilu 

 l^iver and the kettle which holds Lake Compounce. When the land rose 

 and the Pequabuck extended its fiow^ to Plainville the heaviest accumu- 

 lation was yet southward in the restricted estuary, now at 180 to 200 

 feet. As the estuary waters gave place to rivers the Pequabuck Kivor 

 was obstructed by its owr delta and was diverted northw^ard, on the 

 weaker side of the delta.* It should be noted that no heavy tributary 

 joins the Farmington River north of the Pequabuck. 



At and below^ the summit marine plane the evidences of standing water 

 in the great valley are profuse. Many deltas of weak streams lie along 

 the valley walls. A good locality is the flank of the Bristol highland 

 the Avhole leng-th of the Meriden quadrangle. Good delta terraces are 

 suggested at Mixville and at Marion and northward to Compounce 

 Pond; also at Polkville north of Bristol. The summit delta plain at 

 Bristol is handsome. The smooth gravel plain abuts sharply against 

 the Bristol hills; with clear limits. The improved road leading north 

 from the mouth of the gorge is on the contact between rock and till on 

 the west and the delta plain on the east. An important fact is that here 

 the material of the delta is only sand, while south of the river it is 

 gravel. The apex of the delta at the mouth of the river gorge is about 

 245 feet, according to the Meriden sheet. The broad plain east and 

 south is 240 feet, which is taken as the summit marine level. 



The singular ridge along the east side of Compounce Pond appears 

 to be a strip of the delta deposited between ice blocks.' The top shows 

 similar height and slope as the adjacent delta plain. 



FITCHBURG DISTRICT 



Passing eastward from Millers Falls, by the Fitchburg Eailroad, over 

 the highlands, Ave drop to the marine level at Fitchburg. Here is the 

 delta filling of .Whitman River and Baker Brook. The altitude of the 

 marine level is taken as about 400 feet (the threshold of the railroad 

 station being 440.66 feet). 



Abundant evidence of the standing water is seen east of the city, in 

 the valley holding Baker Brook and in the broader valley southeast of 

 the city. The Lundenburg State road Avill lead the observer across the 



*A good example of similar diversion is that of the Iromohawk River on the Schenev- 

 tady- Albany delta (78, page 12 h 



