425 
it is only necessary to bear in mind that these enormous 
frozen rivers, as they may be termed, move forward with a 
slow motion and with an overwhelming force. Their surfaces 
become the depositories of the fallen fragments of the rocky 
valleys into which they descend. These accumulate, and are 
arranged either at each side of the valley, forming what are 
termed lateral moraines — in the form of united moraines, 
when they are called medial moraines — or at the end of the 
glacier, when it finally dissolves at the lower extremity, and 
thus deposits what is called a terminal moraine. But the 
principal circumstance attending the movement of the glaciers, 
so far as relates to the subject of this paper, is that they leave 
behind them a permanent record of their existence, legibly 
inscribed on the surface of the rocks over which they have 
passed. The nature of this record is very clearly exhibited 
in the plates of the " Study of the Glaciers," by Agassiz. It 
consists in the rounded and polished form of such rocks, and 
in the formation of numerous furrows, grooves, and scratches: 
these are admirably delineated in the plates, which are 
thirty-two in number ; fourteen of them are finished litho- 
graphed drawings ; fourteen are outline charts, or pictorial 
maps, whereon are engraved a brief explanation of the locality 
of each of the views; and the remaining four are detailed 
representations, which do not require an explanatory chart. 
The first and second plates present a panoramic view of' 
the glaciers of Mount Rosa, and, when united, exhibit a con- 
tinuation of the great chain of mountains of that name, with 
the various glaciers descending from them, as they appear 
when viewed from the summit of Rifi'el, above Zermatt, in 
the valley of St. Nicholas. From an immense platform of 
ice, the Porte Blanche, there descend two glaciers, separated 
by a moraine ; one of which Agassiz calls the Glacier Porte 
Blanche, aud the other the Little Glacier of Gornerhorn. 
The Great Glacier of Gornerhorn descends from the same 
