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 
etery, being in some 
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. 
places overlain by till, 
gray clay. On 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. 
and clay was by a gradual transi- Gray Clay overlying. sand. 
tion, occupying one or two feet, 
and three or four feet of the clay 
Fig. 43.—Same, 300 feet east of last; 100 feet 
next above was plainly stratified. long; 8 to 10 feet deep. 
The rest of the clay was very 
compact, with no evident lamina- 
tion, breaking into iron-stained, 
Gray clay overlying sand, which overlies till. 
angular pieces, and contained oc- Fig. 44.—Same, 500 feet farther east; 100 feet 
casional pebbles. In the midst pO ERE Pe oe ECHL SE 
of this clay (Fig. 43) a horizontal sandy layer was very distinctly shown 
