(* "Observations sur les Phenomenes d'Erosion en Norwege"
1857.)
Although even in such cases it remains to be proved whether a general crust of continental ice, like that of Greenland described by Rink (see above, Chapter 13), would not account for the deviation of the furrows and striae from the normal directions which they ought to have followed had they been due to separate glaciers filling the existing valleys.
It appears that in general the upward movements in Scandinavia, which have raised sea-beaches containing marine shells of Recent species to the height of several hundred feet, have been tolerably uniform over very wide spaces; yet a remarkable exception to this rule was observed by M. Bravais at Altenfjord in Finmark, between latitude 70 and 71 degrees north. An ancient water-level, indicated by a sandy deposit forming a terrace and by marks of the erosion of the waves, can be followed for 30 miles from south to north along the borders of a fjord rising gradually from a height of 85 feet to an elevation of 220 feet above the sea, or at the rate of about 4 feet in a mile.*
(* "Proceedings of the Geological Society" 1845 volume 4
page 94.)
To pass to another and very remote part of the world, we have witnessed so late as January 1855 in the northern island of New Zealand a sudden and permanent rise of land on the northern shores of Cook's Straits, which at one point, called Muko-muka, was so unequal as to amount to 9 feet vertically, while it declined gradually from this maximum of upheaval in a distance of about 23 miles north-west of the greatest rise, to a point where no change of level was perceptible. Mr. Edward Roberts of the Royal Engineers, employed by the British Government at the time of the shock in executing public works on the coast, ascertained that the extreme upheaval of certain ancient rocks followed a line of fault running at least 90 miles from south to north into the interior; and what is of great geological interest, immediately to the east of this fault the country, consisting of Tertiary strata, remained unmoved or stationary; a fact well established by the position of a line of Nullipores marking the sea-level before the earthquake, both on the surface of the Tertiary and Palaeozoic rocks.*
(* "Bulletin de la Societe Geologique de France" volume 13
1856 page 660, where I have described the facts communicated
to me by Messrs. Roberts and Walter Mantell.)
The repetition of such unequal movements, especially if they recurred at intervals along the same lines of fracture, would in the course of ages cause the strata to dip at a high angle in one direction, while towards the opposite point of the compass they would terminate abruptly in a steep escarpment.
But it is probable that the multiplication of such movements in the post-Tertiary period has rarely been so great as to produce results like those above described in Moen, for the principal movements in any given period seem to be of a more uniform kind, by which the topography of limited districts and the position of the strata are not visibly altered except in their height relatively to the sea. Were it otherwise we should not find conformable strata of all ages, including the primary fossiliferous of shallow-water origin, which must have remained horizontal throughout vast areas during downward movements of several thousand feet going on at the period of their accumulation. Still less should we find the same primary strata, such as the Carboniferous, Devonian, or Silurian, still remaining horizontal over thousands of square leagues, as in parts of North America and Russia, having escaped dislocation and flexure throughout the entire series of epochs which separate Palaeozoic from Recent times. Not that they have been motionless, for they have undergone so much denudation, and of such a kind, as can only be explained by supposing the strata to have been subjected to great oscillations of level, and exposed in some cases repeatedly to the destroying and planing action of the waves of the sea.
It seems probable that the successive convulsions in Moen were contemporary with those upward and downward movements of the glacial period which were described in the thirteenth and some of the following chapters, and that they ended before the upper beds of Number 5, Figure 49, with its large erratic blocks, were deposited, as some of those beds occurring in the disturbed parts of Moen appear to have escaped the convulsions to which Numbers 2, 3, and 4 were subjected. If this be so, the whole derangement, although Pleistocene, may have been anterior to the human epoch, or rather to the earliest date to which the existence of man has as yet been traced back.