50 A. BLYTT. [NO. 1. 



arc 12'. In some places (e. g. Constantinople) this stage begins 

 with freshwater formations which are covered by marine ones 

 (cfr. Suess Antlitz der Erde. I. p. 419). From a profile taken in 

 Hungary (by Peters in' Sitzber. d, Wien. Akad. math. natv. CI. 

 1861), the stage has 4 alternations. 



After that stage follow the Pliocene Congerian beds, which 

 in the Vienna basin, are only represented by brackish- water 

 formations, according to Fuchs (Jahrb. d. K. K. geol. Reichs- 

 anst. 1875) with 4 alternations; arc 13'. And with these beds 

 the marine formations of the Vienna basin, Hungary, and Sieben- 

 burg are closed. Volcanic eruptions in those regions began 

 already in the Oligocene epoch; they became most frequent in 

 the Miocene, and in that epoch the Alps increased to great heights. 



In the Mayence basin, after Oligocene beds (marine sand 

 of Weinheim and septaria-clay) a fresh-water formation first 

 follows; then the Miocene epoch began with a rising of the 

 sea. But during volcanic eruptions the basin was upheaved and 

 became more and more fresh. A continuous formation of beds 

 took place. Above the Cerithium lime-stone, the Corbicula lime- 

 stone and the Litorinella clay became deposited, with altogether 

 20 alternations, or somewhat more (cfr. Lepsius: Das Mainzer- 

 becken). All those layers are Miocene. 



We pass now further on in time. The Pliocene has four 

 oscillations 13', 14', If)' and 16'. We have already mentioned 

 the Congerian beds of the Vienna basin. In England there are 

 three oscillations: Coralline Crag (14'), Red Crag (15') and 

 Cromer clay or Westleton Shingle (16'). Profiles of these are to 

 be found in the Quart. Journ. Geol. Soc. London 1871 (by Prest- 

 triclu. The climate of Europe began to be colder in the Pliocene 

 epoch. Already the oldest Pliocene beds in England contain 

 stones that must have been transported by ice, and towards 

 the close of the Pliocene epoch great glaciers were already 

 formed; after the Pliocene comes the Glacial age. We have 

 seen, how, during strong and widely spread volcanic erupti- 

 ons, previously marine basins were, in the Oligocene, and especi- 

 ally in the Miocene epochs, upheaved over the surface of the sea, 



