CLAYS IN THE HADLEY LAKE. 699 



but in places certainly of very great, tliickness, and the clav has done 

 more than all the other beds to obliterate the vertical irregularities impressed 

 upon the basin by the ice. It still underlies the whole flood plain of the 

 Connecticut, and although the river in its oscillations has cut in the clay a 

 broad and deep channel, it has not cut through to the base of the clay 

 stratum, except opposite North Hadley, where a reef of sandstone projects 

 through, and at the knee of the great bend, where the river has worn into 

 a submerged drumlin. This great bed of clay continues southward to the 

 Westfield River, where the conditions of the Deei-field are exactly repeated, 

 and the clays are replaced b}^ the fine delta sands. 



It extends everywhere iinder, and sometimes very far under, the shore 

 terrace, notably in the case of the Mill River delta in Northampton, where 

 the clays spread under the delta deposits clear up to the " Bay State," near 

 Florence, where they are worked in large brick pits and rest on till with a 

 thickness of 23 feet. There are also large pits near the asylum. It reaches 

 apparently its greatest thickness under the Northampton and Hadley 

 meadows and in the East Sti'eet basin in Amherst. At the Belden silk 

 mill, near the station in Northampton, the clay was. reached beneath a few 

 feet of sand, and its bottom was 140 feet below the surface — that is, about 

 12 feet below sea level. Beneath the clay was 10 feet of red sand. 

 The clay was piei'ced 112 feet at the piers of the overhead l)ridge at the 

 Northampton station. 



The trial piles at the Northampton bridge over the Connecticut, heavy 

 timbers well jointed and hooped, were driven 113 feet below low water — 

 that is, about 13 feet below sea level — without finding bottom, and after 

 the pile had rested in its place for the night the first blow in the morning 

 advanced it as much as the last of the night before, which would have 

 hardly been possible in any material except a very plastic clay. The piles 

 for all the piers of the bridge were driven 30 feet below the river bottom 

 in the same clays after passing- through the river gravels. 



About 1,500 feet north of the bridge the clays rise in the high western 

 bank of the river about 72 feet above low water. This is just opposite and 

 only a few yards from the south end of the Catnp Meeting cutting (see 

 p. 677), and the clays between are continuous. Thus their maximum 

 thickness may be about 218 feet. About the same distance south of the 

 bridge they are exposed for a long waA- in the river bank, at the south end 

 of Hadley .street, a locality furnishing fossil leaves (see p. 738) and an 



