122 On Lines of Ancient Sea-Levels. 



dergone since the existence of the present marine fauna (for 

 Scania has been depressed beneath the Baltic, whilst other 

 parts of Sweden have been raised), and I may be permitted to 

 add, that the extent to which elevations have affected the 

 north-eastern corner of Europe has been recently pointed out 

 in Russia by my companions and myself. 



In the prelude to the report on the part which M. Bravais 

 has performed in these labours, we are put in possession of the 

 results of the valuable researches of Professor Keilhau, who, 

 prior to the French expedition, had ascertained the levels of 

 different accumulations, all supposed to be marine, from the 

 sea-shores to altitudes of above 600 feet in the interior of 

 Norway. 



The greater number of geologists have for some time be- 

 lieved, that these phenomena could alone be satisfactorily ex- 

 plained by upheaval of the land, and M. Bravais has, by a new 

 method of proof, arrived at the same conclusion. 



Passing about a year in the environs of Hammerfest, he ob- 

 served that terraces of gravel in some spots, and marks of ero- 

 sion on the face of the cliffs at others, indicated at least two 

 ancient lines of sea-level, which extended from the coast far 

 into the interior along the sides of the sea-loch of Alten fiord. 

 Availing himself of the water-mark left by the line of sea- 

 weeds (Fucus vesiculosus), and estimating from that horizon 

 an approximate mean level of the tide, he instituted a series 

 of exact measurements of the altitude of both the lower and 

 upper sea beaches, or ancient water-marks upon the rocks, at 

 six different stations between the mouth of the fiord and its 

 southern extremity, a distance of ten to eighteen leagues, and 

 he arrived at the striking result, that the two terraces of Alten 

 fiord, which at first sight, or seen only to a limited extent, 

 seemed to be horizontal and parallel, are, when measured ri- 

 gorously, found to rise from the levels of 46 and 92 feet (En- 

 glish) above the sea near the mouth of the firth to the heights 

 of 90 feet and 220 feet at its further or inland extremity ! In 

 referring you to the Memoir for the ingenious and accurate 

 methods employed by the author to obtain these results, and 

 of which M. de Beaumont has given a very clear account, I 

 will here simply direct your attention to some of the chief geo- 

 logical considerations with which they are involved. 



