82 SEFSTROM ON THE FURROWS WHICH TRAVERSE 
in conjunction with some common geological occurrence, of 
which these furrows may be the yet remaining marks. Pro- 
ceeding with such a view, I determined to investigate how far 
these furrows extend over all our mountains; and whether 
their direction is everywhere the same; as well as (should they 
not be found alike) the nature of the variations which occur, 
and the circumstances under which they have originated. 
From my avocations for a time confining me to the im- — 
mediate vicinity of Fahlun, 1 have there more minutely in- 
vestigated the mountain-furrows, and come to a result which 
pointed out a plan for the researches which I afterwards had 
an opportunity of making in other parts of Sweden, as well as 
for those made by the students of the mining-school, who united 
zeal to an accurate knowledge of the object in view. It is the 
result of these investigations that I have now the honour of pre- 
senting to the Royal Academy, with the view that investiga- 
tions on this subject may be made by others in places where 
they have not hitherto been undertaken; and I shall also draw 
attention as much as possible to the method which I have pur- 
sued, in order to prevent errors in the observations. I shall first 
describe my investigations in the district of Fahlun, and, gene- 
rally, give an account of the experiments which circumstances at 
the time induced me to undertake. It is impossible to make this 
hypothesis clear to every one, and to give life to the details, with- 
out first saying some few words on the theory respecting the cause 
of this phenomenon, which gives the investigation its leading 
feature and enables the reader to comprehend the details,— 
without which clue it would appear of little importance. 
The circumstances which I have noticed lead to the conjecture 
that a mass of large and small stones, sand and gravel, by the 
action of water, have been rolled and washed forward over the 
already exposed surface of the earth, by which these stones, 
rolling against each other in their course, have produced the 
pebbles which lie collected in heaps on the extensive hills which 
we call dsar (ridges), and of which the heaviest, less subject to roll 
under the pressure of the weight of the masses of stone lying 
above them, have slidden over and around the surface of the 
mountain and furrowed it, in the same manner as a polished 
surface of marble is furrowed by grains of sand under the pres- 
sure of the finger when drawn briskly over it. To name this pro- 
bable geological occurrence I shall call it the Boulder-flood (Rull- 
stensflod), from the name Boulder (Rullsten, Gerélle), by which 
fae al 
