MODIFIED DRIFT OF THE LAKE DISTRICT. 135 
deposits have been used for brick-making, and the latter has been exca- 
vated at two places an eighth of a mile apart. It is overlaid by about two 
feet of till, and a well showed the thickness of clay to be 13 feet, under 
which was a water-bearing layer of gravel. 
From this clay-bed a valley about 4o feet in depth descends to the 
south at the west base of the hill, which on this side is ledge. The bot- 
coe tom and the steep west side of 
Leet is Clay:beds. the valley are composed only of 
ae Bie modified drift, being fine silt or 
he Lines of section, and; while only till with many 
fig a." ™ large angular boulders up to 10 
Upper till. Sand. “Ledge. 
“ 
Mewes eww en eee eee 
Fig. 33.—MApP OF A SMALL AREA IN ALTON, _ Fig. 34.—SECTION CROSSING FIG. 33- 
TWO MILES SOUTH FROM CLAY POINT. Horizontal scale, 1 inch—} mile; ver- 
Scale, 1 inch=3 mile. Contour lines are tical scale, 1 inch—=400 feet. The 
shown for each 10 feet, the highest being dotted line at the base represents 
200 feet above the lake. the level of the lake. 
feet in size forms the top of its west bank and the irregular surface, 
which thence descends westerly to the alluvial area previously described 
on page a The contour of this locality is shown in Fig. 33; and Fig. 
: . 34 shows the apparent position of the sand 
underlying the very coarse till. Less than 
a mile farther south a similar valley is seen 
from the highway on its east side a short 
distance north of M. Adams’s house. The 
contour and probable section at this place 
are shown in Figs. 35 and 36. Here it 
Upper till. Sand. Upper till. 
Fig. 35.—Mapr OF A SMALL AREA w. comic ee E. 
IN ALTON, THREE MILES SOUTH 
FROM CLay Port. peers as Os SiS uta roe eee ne, 
Scale, 1 inch=3 mile. Contour Fic. 36.—SECTION CROSSING FIG. 3 Ge 
lines are shown for each 10 feet, | Horizontal scale, 1 inch—} mile; vertical scale, 
the lowest being 50 and the I inch= 400 feet. The dotted ine at the base 
highest 200 feet above the lake. fepresents the level of the lake. 
