BRAVAIS ON LINES OF FORMER SEA-LEYEL IN FIN MARK. 535 



of these marks may serve as an inferior limit, assisting us in fixing 

 the ancient level of the sea. 



Besides this also the study of former elevations enables us to 

 extend our researches over a considerable extent of the -earth's 

 surface, and multiply our observations in every favourable spot. 



In addition to the deposits just alluded to, the sea has also some- 

 times left traces of its former presence on the shore, which, if they 

 cannot be called more certain, are at least more precise ; and not 

 unfrequently the ancient beach is at a certain distance inland from 

 the present one, and is indicated by the most incontestable marks. 

 To follow one of these ancient lines of level for a considerable 

 distance, to convince oneself at every interruption of the former 

 continuity of the different fragments which now form the only 

 visible mark, to prove whether the line we thus re-construct is 

 or is not horizontal — this is a course of proceeding by which we 

 may hope to make out the amount of disturbance that has taken 

 place in one direction, viz. along the line of the sea-coast. If, 

 however, the coast is deeply intersected by long and narrow bays, 

 or if it is separated from the open sea by a number of detached 

 islands, we are enabled by similar measurements to obtain ad- 

 ditional data, and discover also the amount of elevation in the 

 direction of a line at right angles with the coast line. From such 

 combined series of data we may expect to deduce probable conclu- 

 sions concerning the law which governs these disturbances and 

 elevations of the earth's crust. 



Of all countries there is none of which the coast is better 

 adapted for investigations of this kind than Norway, and by a 

 fortunate coincidence there is no country which offers more dis- 

 tinct marks of alteration of level than this. Professor Keilhau, of 

 Christiania, has collected the observations of all his predecessors on 

 this subject *, and combining them with his own researches has 

 made the fact of this change of level perfectly clear. It thus ap- 

 pears that not only a narrow strip of coast, but the whole of 

 Norway, from Cape Lindesnass to Cape North, and beyond that as 

 far as the fortress of Vardhuus, has been in course of elevation 

 during a period immediately anterior to the historic period. On 

 the south-east coast this elevation has amounted to about 200 yards, 

 and the marks which denote the ancient line of coast, and which 

 have been seen and measured in many points, are so nearly hori- 

 zontal that the deviation from horizontality cannot be appreciated, 

 a circumstance which renders it impossible to account for the change 

 by assuming a number of small local or independent disturbances. 

 This main question has, indeed, been fairly set at rest by M. 

 Keilhau's important investigations, but it still remains to carry 



* A list of the heights of all the principal localities in Norway has been 

 published by Prof. Keilhau in the second part of his work, entitled " Goea 

 Norvegica," a work of great detail, and one of which it is intended to give 

 some account in a future number of the Journal. (Prof. Keilhau's book may 

 be obtained in London from Messrs. Williams and Norgate, Henrietta Street, 

 Covent- Garden. ) 



