235 
LUpham. 
short, the typical subglacial till, such as forms the drumlins every- 
where ; but here and in Third Cliff very unusual subglacial de- 
posits of modified drift are associated with it. 
The only organic remains observed in these sections are small 
fragments of lignite, resembling charcoal, which Prof. W. O. Crosby 
and Mr. Bouve found in Third Cliff (at c of fig. 2) scattered 
through a thickness of about six inches of the sand where it rests 
upon stratified clay 10 or 12 feet below the overlying till. The ob- 
ject of our visit together to this section, on the occasion when we 
discovered its remarkable structure, was to search for glacially 
transported fragments of marine shells like those of the till form- 
ing drumlins in Hull, Quincy, the islands of Boston Harbor, East 
Boston and Wintlirop, 1 but no trace of them was found. It seems 
probable that the lignite fragments were wood from preglacial or 
interglacial forests that were overwhelmed by the arctic climate, 
snowfall, and ice-sheet of the last glacial epoch, these fragments 
being enclosed like boulders, gravel, sand and clay in the ice and 
forming part of its englacial drift, until they were washed away by 
streams on its dissolving surface and finally were carried beneath 
the ice to form part of the nucleus of modified drift in this drnmlin. 
A similar derivation was suggested ten years ago for such scanty 
deposits of lignite noticed in the modified drift of Cape Cod ; 2 but 
there the deposition evidently took place in an embayment of the 
border of the waning ice-sheet, where the sediments were spread in 
a flood-plain open to the sky and bounded on each side by higher 
areas of ice. 
Peculiar dark bands ( d ), evidently representing successive stages 
of deposition, were noted in the till of Third Cliff above the north 
end of the modified drift and along an extent of about 200 feet to 
the north. Their number is seven or eight, each six to twelve inch- 
es thick, varying from one to three or four feet apart, continuing 
separate throughout, with no branching nor inosculation. The por- 
tion of the till thus banded has a vertical width of 15 to 20 feet 
and dips about five degrees northward, being included between 20 
and 45 feet above the sea. Like the dips at each end of the mod- 
ified drift, it is more inclined than the overlying surface of the drum- 
lin, which is there about 60 to 55 feet above the sea, or than even 
its steepest slope farther down. No stratified layers or seams of 
Proceedings of this Society, vol. xxiv, pp. 127-141, Dec. 19, 1888. 
9 American Naturalist, vol. xiii, pp. 560, 561, Sept., 1879. 
