96 Selections from Huxley 



vast in their amount, as they were slow in their progress. 

 The area on which we stand has been first sea and then 

 land, for at least four alternations; and has remained in 

 each of these conditions for a period of great length. 

 5 Nor have these wonderful metamorphoses of sea into 

 land, and of land into sea, been confined to one corner 

 of England. During the chalk period, or "cretaceous 

 epoch," not one of the present great physical features of 

 the globe was in existence. Our great mountain ranges, 



10 Pyrenees, Alps, Himalayas, Andes, have all been up- 

 heaved since the chalk was deposited, and the cretaceous 

 sea flowed over the sites of Sinai and Ararat. 



All this is certain, because rocks of cretaceous, or still 

 later, date have shared in the elevatory movements which 



15 gave rise to these mountain chains; and may be found 

 perched up, in some cases, many thousand feet high upon 

 their flanks. And evidence of equal cogency demonstrates 

 that, though, in Norfolk, the forest-bed rests directly upon 

 the chalk, yet it does so, not because the period at which 



20 the forest grew immediately followed that at which the 

 chalk was formed, but because an immense lapse of time, 

 represented elsewhere by thousands of feet of rock, is not 

 indicated at Cromer. 



I must ask you to believe that there is no less con- 



25 elusive proof that a still more prolonged succession of 

 similar changes occurred, before the chalk was deposited. 

 Nor have we any reason to think that the first term in 

 the series of these changes is known. The oldest sea- 

 beds preserved to us are sands, and mud, and pebbles, 



30 the wear and tear of rocks which were formed in still 

 older oceans. 



But, great as is the magnitude of these physical changes 

 of the world, they have been accompanied by a no less 

 striking series of modifications in its living inhabitants. 



