FIRST TERTIARY PERIOD. 



473. The great duration of this first Tertiary period may be 

 judged from the fact, that these nummulitic strata have in some 

 localities a thickness of several hundred yards. The marine 

 flora of this period consisted chiefly of Cryptogamous Ainphigenes, 

 Alga3, and monocotyledonous Naiads. 



474. The terrestrial flora consisted of Cryptogamous Acrogenes, 

 such as Hepaticce, ferns, Equisetacete or mares' tails, Characeae, 

 Palms, Conifers, and Taxinese. 



475. In comparing the geography of this period with that of the 

 preceding, it will be seen that, while at some parts the seas are 

 limited by the same shores, at others their outline is completely 

 changed. Upon the northern and southern borders of the Anglo- 

 Parisian basin, the shores lie within those of the Cretaceous age, 

 leaving a band of ground, previously submerged, uncovered. On 

 the south, the shores have retired still further, no traces of the 

 deposits of this stage being found beyond the line which would 

 pass through Montereau, Melun, Paris, Houdan, and Louviers. 

 This basin extended in England, in an irregular direction S.W. 

 and N.E., from Dorchester to Wells, passing through Dorset- 

 shire, Wiltshire, Surrey, Berkshire, and Hertfordshire, in a 

 direction which probably extended much further to the north 

 over the ground now covered by the German Ocean. 



476. In the Pyrenean basin the northern limits of the sea were 

 nearly the same as in the Cretaceous period. It extended probably 

 from the Atlantic Ocean to the Mediterranean, covering all the 

 space upon which the Pyrenees now stand as well as part of Spain. 



477. In the Mediterranean basin the sea entirely changed its 

 place : Provence, which it formerly covered, was now occupied 

 by fresh-water lakes, but the sea appeared above Grasse, in the 

 department of the Yar ; its western shore extended W.N.W. to 

 Castellane, and seemed to follow the line now occupied by the chain 

 of the Alps to Annecy, and beyond that to Grlaris. 



478. Beyond these limits this sea extended to the east, over 

 Sardinia, Italy, the Tyrol, part of Switzerland, and communicated 

 probably with Egypt, the Crimea, the Caucasus, and from the 

 slopes of the Ural to India. Corresponding changes took place on 

 the land, a fresh-water lake existed at Hilly la Montaigne. On the 

 north of the Pyrenean basin the land was uninterrupted from the 

 Ocean to the Mediterranean. 



479. A fresh-water lake covered the part of Provence between 

 Orgon, Martignes, and Aix. These and other details may be easily 

 followed on M. d'Orbigny's map (fig. 181), where the seas of 

 this period are distinguished by the shading number 24. 



480. The changes which took place in the outlines of land and 

 water in consequence of the convulsion which closed the Cretaceous 



125 



