IN THE WHITE MOUNTAINS. 261 
Norway, of the Himalaya Mountains, and the mountains 
of New Zealand, the Andes, and the polar regions at 
the present day, these rivers of ice flowed down the val- 
leys, like a plastic mass of frozen and refrozen snow and 
ice. We learn from the writings of geologists that in 
former times the Alpine glaciers, which now cling to 
the mountain peaks far up the valleys, descended during 
a period of great cold, when the Polar Bear, Reindeer, 
and other arctic animals were spread over Southern Eu- 
rope, and extended far out upon the broad plains of Italy 
and Germany. Such must have been the scene in New 
England during the time of intense cold, known as the 
Glacial Period. But before theorizing, let us . present 
the facts which seem to us new, and to confirm the opin- 
ions. that have been before expressed by some of our 
geologists, that the principal valleys of the White Moun- 
tains have been filled with these rivers of ice. Our ob- 
servations only relate to the eastern part of the mountains. 
Let us first explain what is meant by ice-marks or 
glacial scratches, striw, grooves, and moraines. The 
rocks and ledges in all the Alpine valleys are grooved 
and fluted by nearly parallel marks made by gravel and 
Pebbles frozen into the bottom and sides of the slowly- 
moving mass of ice. The glacier thus grinds down, 
polishes, and scratches the rocks over which it moves. 
So steady and uniform is the motion of these immense 
bodies of ice, that the marks preserve a remarkably 
uniform course over the uneven surface of the valley. 
Sometimes a huge ledge projects into the valley. Around 
this the glacier sweeps, and the marks are curved at this 
point. Where the glacier debouches on to a broad plain, 
the ice-marks tend to radiate outwards, fan-like, from the 
mouth of the valley. L a 
