and Orography of the Earth's Surface. 311 



the kind, from the actual state and place of the protuber- 

 ances, chains, and cavities now existing, to those in the re- 

 motest times. A third important document is furnished by 

 the palseontological geography. The countries where iden- 

 tical petrifactions lie in a formation, may be distributed 

 in countries very distant from one another, yet they were 

 covered by the same sea, or even one same channel of 

 salt water, notwithstanding now large chains intervene be- 

 tween them. The certainty of such palseontological indica- 

 tions increases with the more recent age of the formations, 

 and diminishes the more one considers an older formation. 

 The following are some examples. 



A great similarity is known between the miocene beds of 

 Italy, of the Adriatic, of European Turkey, as well as of 

 Austria and Switzerland. This proves the old free commu- 

 nication of the Miocene sea on both sides of the Alps, not- 

 withstanding the differences of climate and the chains inter- 

 spersed. In the Eocene period, the extent of the nummulitic 

 beds indicates the free union of the basins of the Euphrates 

 and Tigris with the Mediterranean and the old eocene sea 

 round the Alps. On the contrary, the difference between 

 the tertiary fossils in Chili and the Pampas {Compt R.Ac, d, 

 Sc 9 Paris, 1843, v. 17, p. 392), shews that these two neigh- 

 bouring countries, notwithstanding under the same latitude, 

 were already separated in the tertiary period by a mighty 

 dike composed mostly of trachytes ; a circumstance which 

 explains also the great mass of agates and of red argil 

 amongst the inferior tertiary beds of the Pampas. In a 

 similar way D'Archiac has been able to prove that the ter- 

 tiary basin of northern France was hardly connected with 

 Belgium and England, because at the place of the present 

 British Channel there extended a chain in NES. direction ; 

 for that reason the shells of the red crag of Suffolk, and the 

 crag of Belgium, are not those of the faluns of the middle of 

 France (Compt. R. Ac. d. Sc, Paris, 1845, v. xx., p. 314). 



On the other hand, the differences in the chalk formation 

 around the Mediterranean, and in the NW. of Europe, com- 

 pel us to believe that in that period there was a great dif- 

 ference of climate as well as a separation of the two seas. 



