Erratic Phenomenon in Valleys. 221 



ficence of his Majesty the King of Prussia, who has deigned 

 to grant me his support in this undertaking. 



A study of equally great importance, with reference to our 

 theory, is that of the history of glaciers. The chronicles and 

 the registers of the communes situated in the high valleys of 

 the Alps contain scarcely any thing else but the recital of that 

 long struggle between man and the rivers of ice ; a history 

 sad and melancholy when the enemy gains possession of the 

 tract, but joyous and animated when he beats a retreat under 

 the influence of a series of w^arm summers. The same influ- 

 ences and the same reactions must exist in the north of Europe, 

 and the history of the formerly flourishing colonies of Green- 

 land, when it becomes better known, will doubtless tell us of 

 some of those extensive changes in the covering of ice at the 

 North Pole. 



In the present article I shall confine myself to some details 

 regarding the observations I have made since the publication 

 of my work ; and, as these observations are of a very varied 

 nature, some belonging more peculiarly to the domain of geo- 

 log}', and others to that of natural philosophy or of meteorolo- 

 gy, I shall divide the subject into two sections, and intend, in 

 the first, to treat of the erratic phenomenon properly so called, 

 such as I have observed it in Britain. In the second, I shall 

 communicate some of the experiments which I made on gla- 

 ciers last summer, during my sojourn upon them, and in the 

 course of my expeditions ; and the whole will be terminated 

 by a short narrative of our residence on the glacier. 



I. The Erratic Phenomenon. 

 I have already said that the most striking discoveries, in re- 

 lation to the erratic phenomenon, had been made in l^ritain. 

 The most important facts Avhich I have observed may be ar- 

 ranged in three categories : — • 



1. The phenomena proper to the interior of valleys. 



2. The dispersion of erratic blocks in plains, at gi'eat dis- 

 tances from their origin. 



3. Parallel terraces. 



I. Tlie phenomena peculiar to valleys are almost identical at 

 all places where they have been observed. When we studv 



