30 FORMATION OF THE EARTH 



Persia, the region now occupied by the Himalaya, and extended 

 as far as China. This was the Nummulitic sea, so called because 

 it contained enormous quantities of fossil nummulites, coin- 

 shaped, slightly bi-convex, and somewhat resembling the 

 ancient liards. A gulf, which soon filled up, extended over 

 the Paris basin. It was now that the Pyrenees began to emerge 

 between France and Spain. The sea spread further into the 

 Paris basin, finally submerging Beauce, while certain reaches 

 extended to the Central Plateau, and also covered the basin 

 of the Gironde. England then stretched eastwards to Boulogne ; 

 the Paris basin was inundated, and the English Channel, of 

 which there were already signs, although narrower than at 

 present, communicated with the North Sea. Soon, however, 

 the level of the sea subsided and enormous freshwater lakes 

 replaced it in the central parts of France, Spain, and Switzer- 

 land. This was the Oligocene period, which immediately 

 followed the Miocene. The freshwater lakes occupying central 

 France now filled up, and the Alps and the Himalaya attained 

 their greatest altitudes. The sea finally abandoned the basin 

 of the Seine, but, on the other hand, invaded those of the 

 Loire, the Gironde, and the Rhone. Brittany became an 

 island, was separated from the rest of France ; England, on 

 the other hand, was joined to the continent, from which it had 

 been isolated in the preceding epoch. Throughout the rest of 

 the Tertiary period England remained united at first to Artois, 

 whose south-east coasts were washed by the lake that had 

 occupied the basin of Paris. In the Miocene period this became 

 free from water ; the English Channel was driven back to the 

 west of Cotentin, and England, to a large extent, was connected 

 with what was to become Normandy and Artois. 1 This large 

 area was only an isthmus in the Pliocene period, and was cut 

 during the Quaternary period, thus opening the Pas de Calais to 

 the ocean which was to become the Atlantic and which already 

 separated Europe from America and Africa from Brazil. 



The general configuration of land and sea had already 

 become stabilized somewhat earlier, during the Pliocene period. 

 Some regions like Brittany were rather less hemmed in by the 

 sea, which, on the other hand, advanced further along the 

 entire west coast of the Atlantic from Brittany to Spain and 



1 X, 168. 



