Ch. XXXI.] LOWER. MIOCEXE VOLCANIC ROCKS. 677 



M. Hartung, in his account of the Azores, published in 1860, de- 

 scribes twenty-three shells from St. Mary's,* of which eight perhaps 

 are identical with living species, and twelve are with more or less cer- 

 tainty referred to European Tertiary forms, chiefly Upper -Miocene. 

 One of the most characteristic and abundant of the new species, Car- 

 dium Hartungi, not known as fossil in Europe, is very common in 

 Porto Santo and Baixo, and serves to connect the Miocene fauna of 

 the Azores and the Madeiras. 



It appears from what has been said in the twenty-ninth and in the 

 present chapter, that the volcanic eruptions of Madeira, the Canaries, 

 and the Azores, commenced in the Upper Miocene period, and con- 

 tinued down to Post-pliocene times : in some islands of the Canarian 

 and Azorian groups, the volcanic fires are not yet extinct, as the re- 

 corded eruptions of Lanzerote, TenerifTe, Palma, St. Michaels, and 

 others attest. 



In each of the three archipelagoes there are proofs of Miocene sub- 

 marine formations having been gradually uplifted during the outpour- 

 ing of successive lavas, in the same manner as the Pliocene marine 

 strata of the oldest parts of Vesuvius and Etna have been upraised 

 during eruptions of Post-tertiary date. In the Grand Canary, in 

 Teneriffe, and in Porto Santo, I observed raised beaches, showing that 

 movements of elevation have in each of them been continued down to 

 the Post-tertiary period. 



LOWER MIOCENE VOLCANIC ROCKS. 



The Eifel. — A large portion of the volcanic rocks of the Lower 

 Rhine and the Eifel are coeval with the Lower Miocene deposits to 

 which most of the "Brown-Coal" of Germany belongs. The Ter- 

 tiary strata of that age are seen on both sides of the Rhine, in the 

 neighborhood of Bonn, resting unconformably on highly inclined and 

 vertical strata of Silurian and Devonian rocks. Its geographical 

 position, and the space occupied by the volcanic rocks, both of the 

 Westerwald and Eifel, will he seen by referring to the map (fig. 724), 

 for which I am indebted to the late Mr. Horner, whose residence for 

 some years in the country enabled him to verity the maps of MM. 

 Nbeggerath and Yon Oeynhausen, from which that' now given has 

 been principally compiled.f 



The Brown-Coal formation of that region consists of beds of loose 

 sand, sandstone, and conglomerate, clay with nodules of clay-iron- 

 stone, and occasionally silex. Layers of light brown and sometimes 

 black lignite are interstratified with the clays and sands, and often 



* Hartung, Die Azoren, I860 ; also Insel Gran Canaria, Madeira, und Porto 

 Santo, 1864,"Leipsig. 



f Horner, Trans, of GeoL Soc., Second Series, vol. v. 



