96 PKOF. J. LOGAN LOBLEY, P.G.S., ETC., ON 



portion has been destroyed. When it is remembered that 

 the chalk has a total thickness of over a thousand feet, the 

 denuding agencies that have destroyed so much of it will be 

 at once seen to have produced most impoi-tant changes of 

 surface in Tertiary times. 



In the south-east of England, where we now are, the 

 chalk extended over the whole of the Wealden area^ 

 connecting the North Downs of Surrey and Kent with the 

 South Downs of Sussex. The pebbles constituting the 

 Oldhaven Beds, 40 or 50 feet thickness, and forming still a 

 large area in West Kent and East Surrey, are cogent evidence 

 to everyone walking over Blackheath or Croham Hurst of 

 the enormous destruction of chalk that took pJace in early 

 Tertiary times, for these beds are of Lower Eocene age, and 

 every pebble is a highly finished, well rounded fragment of 

 a chalk flint. 



Of the geological Avork and consequent geographical 

 changes accomplished during the Tertiary epoch. Sir 

 Archibald Geilde says : " The Tertiary periods witnessed 

 the development of the present distribution of laud and sea 

 and the great mountain chains of the globe. Some of the 

 most colossal disturbances of the terrestrial crust of which 

 any record remains took place during these periods. Not 

 only was the floor of the Cretaceous sea upraised into low 

 lands with lagoons, estuaries, and lakes, but throughout the 

 heart of tiie Old World, from the Pyrenees to Japan, the bed 

 of the early Tertiary or nummulitic sea was upheaved into a 

 succession of giant mountains, some portions of that sea- 

 floor now standing at a height of at least 16,500 feet above- 

 the sea."* 



The great development of the Jiighest organic forms- 

 which, as has been said, also distinguished the Tertiary 

 epoch is abundantly testified to by the records of the 

 Tertiary rocks. The highest group of plants we have seen 

 Avas well developed at the close of the Secondary epoch, 

 but in the animal kingdom only the orders Marsupialia and 

 Monotremata, of the class Mammalia, were represented, so 

 far as we know, at that time. In the Tertiary formations, 

 however, the fossils introduce us to higher and higher 

 species, until in its latest strata forms are found almost 

 identical with species of the highest existing orders. 



From the Eocene beds of the Paris Basin remains have 



Text Book of Geology^ 3rd edit., \). 963. 



