Bd. III; 2) CONTRIBUTIONS TO THE GEOLOGY OF THE FALKLAND ISLANDS. 21 
This explanation given by Sir Wyville THOMSON, referring the formation of 
the stone-rivers to the slow removal of the waste down the slopes, must be will- 
ingly accepted by everyone who has studied the stone-rivers in nature. The only 
objection, and that a very essential one, is against the idea of the phenomenon as 
a product of present conditions and of the process as still working with full effec- 
tiveness underneath the vegetation that now partly covers the stone-rivers. It ought 
to be added to this review of earlier accounts of the stone-rivers that JAMES Geikie, 
knowing these tracts only from the descriptions of Darwin and THOMSON, has 
compared the stone-rivers with the rubble-drifts of Southern England and considered 
them like these deposits formed in a bygone period, characterized by a climate more 
severe than the present.^ As will be seen in the following this is exactly the con- 
ception of the formation of the stone-runs which I have arrived at independently of 
Geikie’s note, which I did not know of at the time of my visit in the Falkland Islands. 
My first experiences of the process that has formed the stone-rivers of the 
Falkland Islands I made on the small Bear Island in the North Polar Ocean. 
The hill-slopes and valley sides of this island e.xhibit almost everywhere clear 
indications of a moving of the waste from higher to lower ground. Many of the 
small hills show a very marked streakiness of surface, which is due to the peculiar 
arrangement of the detritus, and sometimes the flowing soil forms real streams which 
have much likeness to a glacier in miniature. Evidently these phenomena only 
represent different facies of the displacement of the waste. 
It is not very difficult to find out the mode of formation of the ’mud-glaciers’ 
mentioned above. When in summer time the melting of the snow has reached an 
advanced stage, often the bottoms of the valleys are free from snow, while big 
masses still rest in sheltered places on the valley sides. Every warm and sunny 
day new quantities of water trickle from these melting drifts into the rock-waste at 
their lower edge. As the masses of detritus are composed not only of coarser rock 
fragments such as blocks, slabs, and gravel, but also of finer particles filling the 
interspaces between the coarser material, they are able to absorb considerable quan- 
tities of water. When once saturated, they form a semifluid substance that starts 
moving slowly down-hill. This process, the slow flowing from higher to lower ground 
of masses of waste saturated with water (this may come from snow-melting or rain), 
I have proposed to name solifliiction. 
As the snowdrifts of Bear Island diminish in the course of the summer, new 
ground is exposed, its waste is thawed, and then, saturated with water, it follows 
the slow downward movement. The flowing detritus does not generally move as a 
‘sheet-flood’ with a broad front, but more often flows in some slight depression of 
the slope, taking the form of a narrow tongue, offering a most striking parallel to 
■ J. Geikie: The great Ice Age, 3d ed. (London, 1874) P. 722 — 723. 
