Narrative of the surveying voyages of his majesty's ships Adventure and Beagle (vol.3)

ADDENDA. 623 admitted by all that the grooves on the solid rock were formed by the passage of these boulders over it. Although the minor inequalities of the surface of the land appear to have had no influence whatever on the action which produced the scratches, yet the larger features, as the general bearing of the main valleys, appear to have determined their direction. Sir James distinctly states that the scoopings and furrows have precisely that form whicli the long action of torrents tends to produce on a solid rock ; but he adds, and I believe most truly, tliat the furrowed surface produced by such means is smooth, and not deeply scored and scratched. It is indeed utterly inconceivable that large stones should be carried along as if " independcntli/ of their graviti/" by any ordinary means, witli such velocity, as to mark with horizontal lines the perpendicular face of a rock. From these facts, — from the presence of great erratic blocks, from the steepness of one face of the grooved hills, and the tail of sediment stretching out from tlie other, Sir James Hall, having in his mind the recorded cases of the great waves consequent on earth- quakes, inferred that a vast deluge had burst over the country from the westward. M. Brongniart, and lately M. Sefstrcirn {U Imtitut, February 22d, 1837), have described phenomena in Sweden almost identical with those of Scot- land. The rocks are there grooved and scratched,* even to the height of 1500 feet, in north and south lines, parallel to the valley of the Baltic and of the Gulf of Bothnia ; but they are considerably ^deflected by the larger inequalities of surface. The north side of the hills are most affected, whilst from the southern side, long ridges, called oasars, stretch out ; they are composed of sand and waterworn materials, and appear to be simi- lar, but on a much larger scale, to the tads of diluvium in Scotland. In Sweden, however, the erratic blocks always lie on the surface of these ridges, and are not embedded within them : but M. Sefstrom says, that at the time when the grooves were formed, enormous masses of rock were torn from the mountains. In the United States, the phenomenon of the grooved rocks appears to be developed in an extraordinary manner. Pro- * Mr. Lyell, moreover, describes (PMlosoph. Transact., 1835, p. 18), the rocks of gneiss on the beach near Oregrund in Sweden, as being so " smooth and polished, that it is difficult to walk on tliem." Further on (p. 21), he describes the large bodies of ice, which are annually packed on this coast, so as to be eighteen feet tliick ; here then we have the same phenomena as in the Alps ; and great icebergs in movement, instead of solid glaciers. More lately M. Berzelius has sent specimens of these rocks, " polished as if by emery in a constant rectilinear direction" (Edinb. New Phil. Journal, vol. 1., p. 313), to Paris, accompanied by a letter to M. Elie de Beaumont.