PLATE 15. 
Figure 1.— Banpep Cuiay, Woopsvitim, N. H. 
The specimen figured shows the difference in thickness between the layers of banded clay. The 
regularity of interval is what might be called ‘‘average”’ for banded clay. The thickness of the summer 
layer is more variable, as a rule, than the winter layer. The summer layers show in light color. It 
may be seen that these light layers vary between 1/32 of an inch to as much as ¢ of aninch. Where the 
summer layers are very thin, the winter layers also show thinning. 
Figure 2.— Tur rinest BAanpED SLATE aT SQUANTUM. 
This finest slate occurs at the highest observable outcrop of slate at the Squantum Head locality, 
about 800 feet above the tillite. Chlorite is the predominant mineral in its composition, giving a light 
green tint. It is most probable that erosion of a melaphyre area is responsible for the material of this 
finest banded rock in the glacial series of Squantum. 
Figure 3.— Banpep State, Squantum Hap. 
The light layers are of coarse material and the dark, fine. The regularity of interval is marked. 
The irregularities are no greater than in the specimen of banded clay shown in Figure 1. Note the 
fine lines in the coarse similar to those seen in Plate 16. 
Figure 4.— Banprep Suars, Squantum Hap. 
Weathering has not acted to the same extent on this specimen as on the one shown in Figure 3. 
The clearness with which banding shows in much of the slate without sandstone layers is due to weath- 
ering. 
