THE SCANDINAVIAN MOUNTAINS. 113 
or shaftered to pieces on the spot. If, on any part of these, fur- 
rows were met with, it would be clear that the shattering had 
taken place after the passing of the boulders ; but no such dis- 
covery has hitherto been made. Meanwhile it is also uncertain 
whether the shattering to pieces occurred before that flood, be- 
cause, probably, the flood could not have reached so high up as 
to the mountain ridges. The circumstance which Mr. Wegelin 
observed on the higher rocks around this place, namely, large 
detached fragments which are not worn by rolling, makes the 
case so much more doubtful, until we are enabled to investigate 
the circumstances more narrowly. Where I have had an oppor- 
tunity of seeing the same phenomenon in some porphyry rocks 
to the westward of Lake Siljan, similar fragments had loosened 
themselves, by the action of the atmosphere, from the steep and 
fissured cliffs. 
§7. 
Of the probable rapidity of the Boulder-stream. 
When I first began my observations, I remarked in several 
places, that if two furrowed rocks succeeded each other in the 
direction of the furrows, and were near each other, the northern- 
most was on the resisting side, and, if it was not too steep, fur- 
rowed as low down as the plain; whilst, on the contrary, the 
resisting side of the latter had been sheltered by the projecting 
rock situated before it; by which it is evident that where the 
boulders passed over the highest top of the first rock they struck 
on the latter at a certain depth. If we can therefore determine 
the point where the boulder left the former rock, as well as the 
point where it struck upon the latter, and measure their di- 
stance both horizontally and on the diverging line, we might hope 
that, assuming the dip to a second was the same formerly as now, 
we could thus calculate how great the horizontal rapidity of the 
boulders had been. 
A diligent search has also been made to find a point where 
such a measurement could be undertaken, but hitherto without 
success, partly on account of the distance being too inconsider- 
able between the points, partly because the places where there 
might have been some hopes of finding such a situation have 
been covered with large masses of earth; and besides this, 
VOL, Ill, PART IX. I 
