THE GLACIAL THEORY. 



PART II. 



Changes in Glaciers — Their descent — Occurrence of dirt and gravel beds 

 — Boulder stones — Moraines — Ice-tables — JSJeedles and gravel cones — 

 Chasms — Arched hollows in the lower part of glaciers — Occurrence of 

 lakes and torrents — Striated Rocks. 



** The flanks of all glaciers are more or less inclined towards the rocks 

 forming their boundaries." Jgassiz. 



" The flanks of the glaciers are inclined towards the mass of rocky 

 fragments (medial moraine) in the glacier of the Aar." Agassiz. 



" All glaciers have chasms and crevices." Agassiz. Hugi. Saussure. 

 Charpentier, 



" I have seen the surface of the lower glacier of the Aar filled mth 

 small cracks of an inch in length." Agassiz. 



" Chasms are formed where a sudden inclination of the bed of the 

 glacier occurs, as in the large glacier of Aletsch." Agassiz. 



" The chasm in one of the glaciers of Mont Blanc is 100 feet wide.'* 

 De Saussure. 



*' The depth of a chasm in the lower glacier of the Aar is 1 20 feet." 

 Hugi. 



On the 27th December, 1819, a large portion of the glacier of Randa 

 was detached from one of the rocky walls of the summit of the Weiss- 

 horn, and was precipitated with incredible noise over the subjacent 

 glaciers." Venetz. 



"At the junction of the glaciers of the Finsteraar and Lauteraar, 

 Mons. Hugi constructed a small hut in 1827, which since that period 

 has advanced 200 feet towards the mouth of the valley." Agassiz. 



"M.M. Venetz, Charpentier, Hugi, and Agassiz, all observed descents of 

 glacial masses in the elevated districts of the Alps." 



" Layers of mud or gravel always occur beneath glaciers." Agassiz. 

 Charpentier. De Saussure, &c. 



Raised boulders are frequent near the cascade of Pissevache, and 

 below the baths of Lavey." Agassiz. 



" They also occur on the glacier of the Aar." Agassiz. 



*' They also occur on the Saleve." Be Saussure. 



"The fragments of rock composing moraines are proved to have been 

 derived from the rocks bounding the glaciers, by their mineral con- 

 struction." Agassiz, 



