2 Vallentin, Notes on the Falkland Islands. 



half that distance in diameter. The blocks of quartz-like 

 rock of which it is composed vary very considerably in 

 size, but in form are all very similar, the length generally 

 exceeding the breadth, and they invariably have their 

 ends rounded off by weathering. This fact seems clearly 

 to indicate that these rocks have been detached from 

 their original beds ages ago. These stones are not 

 heaped up in any way, but are always spread fairly 

 uniformly over the ground ; giving one the impression 

 that they had been scattered broadcast. A main body 

 or central stream can always be distinguished in every 

 ^stone-river,' while lesser affluents can be observed joining 

 the main stream at almost right angles. Close examina- 

 tion of every ' stone-river,' always shows that the rocks in 

 the upper portion are covered with lichens, and that these 

 lowly plants decrease in quantity as one proceeds down 

 the slope, till within a short distance of the foot the rocks 

 are bare of vegetation. 



Darwin" and Sir Wyville Thomson* are the two most 

 recent authors who have touched on the structure and 

 formation of the ' stone-rivers.' Darwin thinks that 

 their present position is due to some enormous convulsion 

 of nature. Sir Wyville Thomson ventures the theory that 

 ..." The blocks of quartzite in the valleys are derived 

 from the bands of quartzite in the ridges above, for they 

 correspond in every respect ; the difficulty is to account 

 for their flowing down the valley, for the slope from the 

 ridge to the valley is often not more than six to eight 

 degrees," ..." The process," he continues, " seems to be 

 this : The beds of quartzite are of different hardness ; 

 some are soft, passing into crumbling sandstone, while 

 others are so hard as to yield but little to ordinary 

 weathering." In the process of time the harder blocks 

 tumble from their places, and these displaced fragments 



