NOTES ON A SUMMER TOUR IN NORWAY. 79 
like sentinels on jutting points and ledges, the huge mounds of 
morainic aébris at the heads of the valleys, and the wild disorder 
of crags and boulders scattered over the former paths of glaciers, 
combine to make a picture which no after amount of sight- 
seeing is likely to cause a geologist to forget. The whole 
country has been moulded, and rubbed, and polished by one 
immense sheet of ice, which could hardly have been less than 
6,000, or even 7,000, feet thick.” —Gerkie. 
Now, when we consider that a mass of ice 1,000 feet thick 
exerts on the subjacent rock by its own weight alone a force of 
450 lbs. per square inch, that the ice sheet which covered 
Scandinavia at the height of the glacial period was six or seven 
times this thickness, and that the movements of this great mass 
of ice took place more rapidly, and with irresistible force, down 
the valleys which were in existence before this great ice mantle 
covered the country, it does not seem at all improbable that 
the moving ice, aided by the morainic débris attached to its 
lower surface, and by the flowing of water beneath, would 
scoop out great hollows in the valleys where the pressure of the 
ice was greatest and the rocks the softest. Taking everything 
into consideration, erosion by moving ice accounts best for the 
occurrence of rock basins in valleys, whether these are now filled 
by salt or fresh water; there are, however, some difficulties in 
the way of fully accepting this view; but this would take me into 
controversial matters, which would occupy your time too much, 
and, perhaps, result in but little profit. The principal facts which 
I want you to lay hold of with regard to both the Norwegian fjords 
and Scottish sea-lochs are, that they occupy submerged valleys, 
and that some parts of these valleys have, in some manner or other, 
been eroded to an enormous depth by the passage down and 
across them of the vast sheet of ice which once covered 
Scandinavia just as it does. Greenland in the present day. 
Having given you a rapid sketch of the existing physical 
_ conditions of the Scandinavian peninsula, and touched upon 
some of the causes which have led to the present physiography of 
the country, I will now proceed to describe some of its natural 
