ROOM III. GEOLOGY OF THE S. E. OF ENGLAND. 209 



such an accordance in the nature of the fossil remains im- 

 bedded in them, as to indicate that the entire series was accu- 

 mulated while the same conditions of animal life prevailed. 

 The organic remains of the chalk are essentially marine, and 

 consist of many hundred species of shells, corals, radiarise, &c. 

 Numerous species and genera of fishes and crustaceans, and a 

 few remains of reptiles, &c. obtained from the district under 

 review, are deposited in the Gallery of the Museum. In some 

 localities, drifted wood and fruits of terrestrial plants, and 

 bones and teeth of reptiles, and other spoils of the land, have 

 been discovered collocated with the usual marine productions, 

 and these remains have evidently been carried down by rivers 

 and streams into the sea, and transported by currents far 

 from land, till they subsided in the depths of the ocean. 

 One of the most remarkable instances of this kind is the 

 portion of a skeleton of an Iguanodon discovered near Maid- 

 stone, in that division of the cretaceous greensand called the 

 Kentish rag. 



The, Wealden. An extensive series of clays, sands, and 

 sandstones and shelly limestones, upwards of 1,000 feet in 

 thickness, characterized by the terrestrial and fluviatile 

 nature of the organic remains, and the almost entire absence 

 of any relics of marine animals or plants. 



ORDER OF SUPERPOSITION. Such is the chronological se- 

 quence of the formations of the south-east of England; in 

 other words, these several groups of marine and freshwater 

 strata have been deposited in the following order, beginning 

 with the lowermost or most ancient system : 



I. THE WEALDEN : the delta of a river, composed of the 

 alluvial debris of an extensive continent. These strata are 

 spread over the uppermost beds of the Oolite, a vast oceanic 

 formation, but which does not come within the scope of our 

 present observations. 1 



II. THE CHALK : the sediments of an ocean of great ex- 

 tent, deposited upon the Wealden. 



III. THE TERTIARY OR EOCENE : accumulated in depres- 

 sions on the surface of the Upper or White Chalk, consisting 

 of marine, nuvio-marine, and lacustrine deposits. 



With the view of simplifying the subject, the drift, or beds 



1 See " Geology of the Isle of Wight," p. 348. 

 P 



