J. G. ANDERSSON. 
I8 
(Schvved. Südpolar-Exp. 
vey to my mind the idea of a convulsion of which in historical records we might 
in vain seek for any counterpart.» 
This is the account of the marvellous »streams of stones» given by the great 
naturalist, to whom we owe most of our knowledge of the geology of the Falkland 
Islands.^ His mode of describing this splendid and strange phenomenon is very in- 
structive, but his attempt at an explanation offers to the modern geologist only a 
historical interest. 
Sir Wyville Thomson arrived at a much more intimate understanding of the 
formation of the »stone-rivers», and the explanation given by him needs only one 
essential modification to be brought in accordance with the most recent investi- 
gations. Also his account must be quoted here in extenso: 
»In the East Island most of the valleys are occupied by pale gray glistening 
masses, from a few hundred yards to a mile or two in width, which look at a di- 
stance much like glaciei's descending apparently from the adjacent ridges, and 
gradually increasing in volume, fed by tributary streams, until they reach the sea. 
Examined a little more closely, these are found to be vast accumulations of blocks 
of quartzite, irregular in form, but having a tendency to a rude diamond shape, 
from two to eight or ten or twenty feet long and perhaps half as much in width, 
and of a thickness corresponding with that of the quartzite bands in the ridges 
above. The blocks are angular like the fragments in a breccia, and they rest irre- 
gularly one upon the other, supported in all positions by the angles and edges of 
those beneath. 
They are not weathered to any extent, though the edges and points are in 
most cases slightly rounded; and the surface, also perceptibly worn but only by the 
action of the atmosphere, is smooth and polished; and a very thin, extremely hard, 
white lichen which spreads over nearly the whole of them gives the effect of their 
being covered with a thin layer of ice. 
Far down below, under the stones, one can hear the stream of water gurgling 
which occupies the axis of the valley; and here and there, where a space between 
the blocks is unusually large and clear, a quivering reflection is sent back from a 
stray sunbeam. 
At the mouth of the valley the section of the ‘stone-river’ exposed by the sea 
is like that of a stone drain on a huge scale, the stream running in a channel 
arched over by loose stone blocks, or finding its way through the spaces among 
them. There is scarcely any higher vegetation on the ‘stone-run’; the surface of 
every block is slippery and clean, except where here and there a little peaty soil 
has lodged in a cranny, and you find a few trailing spikes of Nassauvia serpens, 
^ Darwin: Journal of researches into the geology and natural history of the various countries visited, 
by H. M. S. Beagle. London 1840. P. 254 — 256. 
