206 
PHYSICAL HISTORY OF THE 
Mount Washington in the White Mountains 
(that is, having a thickness of nearly six 
thousand feet), moved over the continent of 
North America, — is it so improbable that, in 
this epoch of universal cold, the Valley of the 
Amazons also had its glacier poured down into 
it from the accumulations of snow in the Cor¬ 
dilleras, and swollen laterally by the tributary 
glaciers descending from the table-lands of 
Guiana and Brazil ? The movement of this 
immense glacier would be eastward, and deter¬ 
mined as well by the vast reservoirs of snow 
in the Andes as by the direction of the valley 
itself. It must have ploughed the valley bot¬ 
tom over and over again, grinding all the 
materials beneath it into a fine powder or 
reducing them to small pebbles, and it must 
have accumulated at its lower end a moraine 
of proportions as gigantic as its own ; thus 
building a colossal sea-wall across the mouth of 
the valley. I shall be asked at once whether 
I have found here also the glacial inscriptions, 
— the furrows, striae, and polished surfaces so 
characteristic of the ground over which gla¬ 
ciers have travelled. I answer, not a trace of 
them ; for the simple reason that there is not 
