260 SURFACE GEOLOGY. 



contributions from the mountains. It suggests the probabihty of the 

 transportation of those at Manchester and Nashua by the local Merri- 

 mack glacier. The ice from the White Mountains would meet the tribu- 

 tary glaciers from the west, and be compelled to slide upon the east side 

 of the valley exclusively. Hence, whatever boulders came from the 

 White Mountains would be found upon the East Concord or Manchester 

 side of the valley. 



As the continental glacial sheet moved to the south-east, it follows 

 that whatever White Mountain blocks are found in the lower till of the 

 Merrimack basin must have been transported by a valley movement, un- 

 less the natural radial divergence from the mountains could have spread 

 as far west as Manchester. 



Hanover and vicinity. 



Passing over to the Connecticut valley, boulders of a different class 

 present themselves to view, or those derived from Vermont. We also 

 find a large proportion of them brought by the south-east current, 

 although the strias close by run west of south. This confirms our pre- 

 vious suggestions of the existence of both movements in this valley. 



About two miles north of Dartmouth college the kame furnishes the 

 following pebbles, the largest lo inches in diameter : Barre granite, 

 Bethlehem gneiss — both varieties, Huronian diorite, quartz schists with 

 decayed layers, calciferous mica schist — several varieties, clay slates, 

 hornblende schist, jaspery quartz, quartzite, decayed limestone. Else- 

 where this ridge furnishes handsome pieces of red jasper, thought to 

 have been derived from ledges west of the Green Mountains, a distance 

 of 70 miles. The Barre granite has been carried 32 miles. The Bethle- 

 hem gneisses are in place one mile east of this kame for four miles, but 

 they more probably came from Haverhill, 40 miles distant, unless trans- 

 ported down from the Jacob's brook glacier in Orford, on the east side of 

 the valley. These pieces travelled on the Connecticut glacier. The 

 various Huronian and the calciferous schists, and the slates, mostly came 

 from the north-west, involving from a few rods to several miles of car- 

 riage. 



Further cast are heavy deposits of till composed of long travelled and 

 much glaciated stones. Three of them arc represented in the accompa- 



