194 



OLDER PLIOCENE PERIOD. 



[Ch, XIV. 



ENGLISH MILES. 

 1234 



No. 48. 



r ....;..-. .1 Volcanic) A, Upper Eifel. f ^ I Points of eruption, with craters 



t-i-' '-'' '! District / B, Lower Eii'el. . ' and scoria?. 



|<"t,j Basalt. 



3 Trachyte. g] Brown coal. 



N.B. The country in that part of the map which is left blank is almost 

 entirely composed of graywacke. 



There has been a long succession of eruptions in this 

 country, and some of them must have occurred when its 

 physical geography was in a very different state, while others 

 have happened when the whole district had nearly assumed 

 its present configuration. 



The fundamental rock of the Eifel is an ancient secondary 

 sandstone and shale, to which the obscure and vague appella- 

 tion of 'graywacke' has been given. The formation has 

 precisely the characters of a great part of those grey and red 

 sandstones and shales which are called ' old red sandstone ' in 



