MODIFIED DRIFT IN PISCATAQUA BASIN. 



159 



In the west part of the city this kame consists almost wholly of sand, 



and extends in a broad 

 N^??-i>«^w. ridge to Pine Hill cem- 

 etery, being in some 

 places overlain by till, 



Fig. 41. — Sand overlain by Till, Fourth Street 

 WEST of Cochecho River, Dover 



Length of section, 250 feet ; height, 30 feet ; base of but more frequently by 

 section is about 75 feet above the sea. ^^^y (.|^y_ Qn'the south 



side of Fourth street an excavation (Fig. 41) shows it to be horizontal 

 in stratification, except at its sides, where it is obliquely bedded, con- 

 formably to its slope. Here its west side is overlain by the unstratified 

 upper till, in which are numerous angular boulders 2 to 4 feet in diameter. 

 This till also forms a layer two feet thick over the top of the sand, con- 

 taining frequent rock-fragments of smaller size. Another section, show- 

 ing 15 feet of irregularly bedded sand, overlain by a similar deposit of 

 upper till, was observed a quarter of a mile farther south, at a height of 

 about 140 feet above the sea. At these points it seems probable that the 

 sand was deposited in an open glacial channel, bordered by overhanging 

 walls of ice, from which the upper till fell upon the side and was partly 

 strewn upon the surface of the kame. 



A ditch for laying water-pipe on Silver street showed this sand deposit 

 overlain by gray clay (Figs. 42, 43, and 44). The junction of the sand 



Ridges of till overlain by sand, which is overlain by gray clay. 



Fig. 42.— Section along Silver Street, south of Riding Park, Dover. 

 200 feet long ; 6 to 9 feet deep. 



Gray clay overlying sand. 



43- 



-Same, 300 feet east of last ; 100 feet 

 long; 8 to 10 feet deep. 



and clay was by a gradual transi- 



f w. 



tion, occupying one or two leet, 



and three or four feet of the clay ^j 

 next above was plainly stratified. 

 The rest of the clay was very 

 compact, with no evident lamina- 

 tion, breaking into iron-stained, 

 angular pieces, and contained oc- 

 casional pebbles. In the midst 

 of this clay (Fig. 43) a horizontal sandy layer was very distinctly shown 



Gray clay overlying 



Fig. 44- 



-Same, 500 feet farther east ; 100 feet 

 long; 7 to 10 feet deep. 



