152 Mr Poulett Scrope's observations on the Volcanic 



larly along the course of the river Kyll, than at its eastern 

 extremity. The epoch of their activity appears also to be 

 equally recent, dating at least since the formation of all the 

 vallies of the country, into which their lava-streams have in- 

 variably flowed, usurping the beds of the rivulets, which 

 but in very few instances seem to have had force or time 

 enough to execute a new channel to any depth below the level 

 of their former one. Indeed, such is the freshness of aspect 

 which many of the volcanic rocks of this district exhibit, that 

 it requires the silence of all historical records on the subject, 

 to persuade us they have not been produced within the last 

 2000 years. Nor is such evidence, indeed, at all conclusive. 

 It is probable that accounts of phenomena of this kind would 

 rarely reach the meridian of Rome from distant and barbarous 

 districts, unless when they were of a most destructive and ter- 

 rific character, such, perhaps, as that spoken of by Tacitus, 

 and mentioned in a former page ; and if any such occurred 

 during the middle ages, all traditionary account of them may 

 well be supposed to have perished with so much of other and 

 more valuable information. 



The volcanic eruptions of the Lower Eiffel have burst 

 through the exposed surface of the transition slate formation 

 on many points, and on others through masses of floetz strata, 

 which overlie the slate, throughout a considerable part of this 

 district ; these later formations are red sandstone, shell lime- 

 stone, and quader-sandstone. Some of the vents have emitted 

 currents of augitic lava (basalt ;) others have confined them-, 

 selves to the discharge of fragmentary matters. The latter 

 principally, and in some instances almost entirely, consist of 

 broken greywacke, slate, and sandstone, more or less affected 

 by heat, and pulverized. It is probably owing to the clayey 

 nature of these fragments, when reduced to great fineness, 

 that the craters of this country have nearly, without excep- 

 tion, become reservoirs of water, or Maare, as they are called 

 by the natives. Most of them still have small lakes or peat- 

 marshes at their bottom. Some have been drained for the 

 sake of cultivation ; a few appear to have undergone the 

 same process by natural means, either from the lake rising till 

 its weight burst through the banks encircling the crater, or 



