534 



III. TRANSLATIONS AND NOTICES 



OF 



GEOLOGICAL MEMOIRS. 



I. On the Lines, of Ancient Level of the Sea in Finmark. 

 By M. A. Bravais, Member of the Scientific Commission of 

 the North. 



( From Voyages de la Commission Scientifique du Nord, 8fc. ) 



The general question of elevation as bearing on Geology has been 

 one of the most important subjects of discussion in geological 

 science in modern times, and is connected with grave consideration 

 concerning the actual physical condition of our globe. Documents 

 sufficiently exact with regard to the extent of a district now 

 undergoing changes of level, and the alteration effected by each 

 successive movement, thus become of great value, and are likely to 

 be extremely useful hereafter in unveiling the causes of these phe- 

 nomena, which indeed are even more obscure than the phenomena 

 themselves. Now it will readily be seen what is the nature of 

 the difficulties which almost necessarily prevent our obtaining 

 accurate results in such cases. If the change of level is effected 

 very slowly, as in the Gulf of Bothnia and the Bay of Puzzuoli, 

 this slowness of the movement is itself a reason why it is impos- 

 sible to arrive at any solution of the question, except after the 

 lapse of a long series of years. On the other hand, with regard to 

 sudden elevations, of which the extent is more limited, and the 

 cause of which seems to have reference to direct volcanic in- 

 fluence, the few exact hypsometrical data we possess at present 

 concerning the form of the earth's crust, are hardly sufficient to 

 justify geologists in extending their researches beyond the shore, 

 or even in tracing in the interior of a continent the effect of an 

 elevating force. The rarity of these phenomena again, and their 

 being generally quite unexpected, are additional obstacles in this 

 kind of investigation. 



In passing from the recent period to one a little more ancient, 

 it may seem at first that the difficulties necessarily increase, and 

 that, without having first determined the changes at present going 

 on, it would be hopeless to endeavour to throw any light on those 

 of former times. This is not however exactly the case, for an 

 elevated coast line often exhibits numerous marks of the action of 

 water upon it, in the shape of alluvial masses of sand and gravel, 

 and occasionally of clay containing the remains of shells, and each 



