GLACIAL DRIFT. 259 
from deposition, as there has been no sorting of the material. Possibly 
some authors have mistaken these lines for stratification. 
An uncommon feature is the presence of cracks and cavities, or what 
seem like such openings, one or two inches wide, filled with the upper 
gravel. Some masses of the lower till are entirely encompassed by 
them, so that in a section they appear like imbedded, irregular patches. 
The till occupies most of the area, the gravel occurring mainly in the 
veins. The section suggests the possibility of ice occupying the present 
position of the veins at first, and the subsequent infiltration of gravel 
after the melting of the frozen material. There are cases on record of 
large fragments of boulder clay transported by ice as if they were rocks, 
There might have been disturbances in the till, and the interspaces sub- 
sequently filled with gravel. This gravel does not show any cleavage 
structure like that of the lower till. 
The larger of the boulders here are of granite, such as occurs within 
two miles. Those next in size are of the Manchester or Hooksett quartz, 
and mica schists of Andover and Franklin. Stones four inches long are 
composed of the Albany granite, and there are also two kinds of White 
Mountain porphyry. Similar White Mountain boulders occur in a rail- 
road cut very near Massabesic lake, in a compact, elongated moraine, 
different from anything else in the vicinity. 
The greatest distance of carriage indicated by these boulders is 68 
miles. The mica schists travelled about 35 miles. The great bulk of 
the stones on Wilson’s hill has come, therefore, from 35 miles and less. 
A pebble of White Mountain porphyry has been shown to me by a 
resident of Nashua, who found it near his home. This must have 
travelled as much as 86 miles. 
Concorp. 
An examination of the Concord kame showed many stones 8 to 10 and 
12 inches in diameter, more than three fourths consisting of the Con- 
cord granite and associated rocks. I found, also, white quartz, ferrugi- 
nous schists, porphyritic gneiss, trap, blue quartzite, hornblende schist, 
gneiss, and a possible example of Huronian schist from the Connecticut 
valley. Careful search failed to discover any rocks from the White 
Mountains. This indicates that the locality is too far west to receive 
