854 STRATIGRAPHICAL GEOLOGY. [Book VI. — 
Section II.—Oligocene. 
§ 1. General Characters. 
The term “ Oligocene ” was proposed in 1854 and again in 1858 
by Professor Beyrich* to include a group of strata distinct from the 
Kocene beds of France and Belgium, and which Lyell had classed 
as “Older Miocene.” ‘They consist partly of terrestrial, partly of 





Os 
a aN i 
Wied Wy 
\\ SN 
Fic. 407.—OLIGoceNE PLANTS. 
a, Sequoia Langsdorfii (Brongn.) (4) (from Heer’s Flor. Tert. Helvetiw, i. pl. 21); 
b, Chara Lyellii (Forbes) ('?). 



a 
fresh-water and brackish, and partly of marine beds, indicating con- 
siderable oscillations of level in the European area. They conse- 
quently present none of the massive deeper-water characters so 
conspicuous in some of the Kocene subdivisions, Among other 

Fic. 408.—O.icocrens LAMELLIBRANCHS. 
a, Cytherea incrassata (Sow.) (7); b, Ostrea cyathula (Lam.) (2); c, Ostrea flabellula 
(Lam.) (3). 
géographical changes of which they preserve the chronicles is the 
evidence of the gradual conversion of portions of the sea-floor over 
the heart of Europe into wide lake-basins in which thick lacustrine 
1 Monatsbericht, Alead, Berlin, 1854, pp. 640-666, 1858, p. 51. 
