Stone.] 434 [March 3, 
into typical granite boulders, a portion of which were partially dis- 
placed by the glacier from their native bed. Although much of the 
material of the lower till has come from a distance, yet in our exten- 
sive areas of slate this formation is usually finer and more argilla- 
ceous than in regions of crystalline rocks. In Maine where granitic 
and schistose rocks abound, aggregations of lower till commonly take 
the lenticular type, or that of the broad rounded ridge, while in 
areas of slate, and fossiliferous rocks which are but little indurated, 
there is also a decided tendency to form narrower ridges, which 
sometimes have so steep sides as to be mistaken for kames. Asa 
rule they are nearly parallel with the line of glaciation. In N. Ber- 
wick the lower till is composed of two well defined layers. The lower 
is excessively hard and blue, and composed almost wholly of granitic 
fragments like the underlying rock. The upper layer is partly com- 
posed of the local granite, but chiefly of micaceous slates, such as 
are to be found to the northward. These ferruginous slates give a 
browner color to this layer, and it is not so compact as the lower. 
At Portland there are vertical pockets of sand in the ground moraine. 
2. The Upper Till, supposed to consist of the morainal detritus 
which was in the ice, and above the land surface. This formation is 
looser in structure than the ground moraine, in fact it is much like a 
modern moraine. Its color is browner, and its boulders larger, while 
few are distinctly glaciated except in lee of a high, precipitous peak. 
Intercalated masses of clay, sand, or gravel, are common. Accumu- 
lations of upper till are very variable in form and distribution. 
3. The Kames or Eskers, including that part of the till which 
was classified by water and was deposited upon the ice or within ice 
walls. No distinction of names is made between the longer and the 
shorter systems. The systems here described are, however, homo- 
logues of the, Scandinavian aasar, rather than the short ridges (= 
kames) to be found near the terminal moraine. 
4. The Valley Drift, including all that part of the modified 
drift which was deposited after the ice had melted at the place of 
deposition. In valleys of moderate slope the lower layers are usually 
of fine sand or clay, the upper of coarse sand or gravel. 
5. The Lower Marine Clays. ‘These are fine, generally dark 
or bluish, often fossiliferous, especially in the lowest layers. They 
alternate with fine quicksands and contain occasional stones and 
boulders. 
