The mountainous district known as the Eifel, or Eifel-Gebirge, in Rhenish-Prussia, is, as all geologists knowr, famous for the numerous well-preserved craters of extinct volcanos and for the lava-streams, scoriæ, trachyte, and basalt connected therewith.

The English reader will find a short account of the tertiary and volcanic rocks of the Eifel in Lyell’s ‘Manual of Geology,’ chapter xxxi.; and a good geological map of the Eifel and neighbouring districts is appended to a paper, by Sedgwick and Murchison, on the Rhenish Provinces, in the Transactions of the Geological Society, 2nd series, vol. vi. part 2. In the Eifel there are two extensive areas, in which volcanic activity has been especially intense.