REPTILES ABUNDANT. 65 



been the bottom of the sea. The dirt-bed contains exuviae 

 of tropical trees, accumulated through time, as the forest shed 

 its honours on the spot where it grew, and became itself 

 decayed. Near Weymouth there is a piece of this stratum, 

 in which stumps of trees remain rooted, mostly erect or 

 slightly inclined, and from one to three feet high ; while 

 trunks of the same forest, also silicified, lie imbedded on the 

 surface of the soil in which they grew. 



Above this bed lie those which have been called the 

 Wealden, from their full development in the Weald of Sussex ; 

 and these as incontestable argue that the dry land forming 

 the dirt-bed had next afterwards become the area of brackish 

 estuaries or lakes partially connected with the sea ; for the 

 Wealden strata contain exuviae of fresh- water tribes, besides 

 those of the great saurians and chelonia. The area of this 

 estuary comprehends the whole south-east province of Eng- 

 land. A geologist thus confidently narrates the subsequent 

 events : " Much calcareous matter was first deposited [in this 

 estuary], and in it were entombed myriads of shells, appa- 

 rently analogous to those of the vivipara. Then came a thick 

 envelope of sand, sometimes interstratified with mud ; and, 

 finally, muddy matter prevailed. The solid surface beneath 

 the waters would appear to have suffered a long continued 

 and gradual depression, which was as gradually filled, or 

 nearly so, with transported matter ; in the end, however, after 

 a depression of several hundred feet, the sea again entered 

 upon the area, not suddenly or violently for the Wealden 

 rocks pass gradually into the superincumbent cretaceous 

 series but so quietly, that the mud containing the remains 

 of terrestrial and fresh-water creatures was tranquilly 

 covered up by sands replete with marine exuviae." ( 39 ) A 

 subsequent depression of the same area, to the depth of at 

 least three hundred fathoms, is believed to have taken place, 

 to admit of the deposition of the cretaceous beds lying above. 

 From the scattered way in which remains of the larger 

 terrestrial animals occur in the Wealden, and the intermix- 

 ture of pebbles of the special appearance of those worn in 

 rivers, it is also inferred that the estuary which once covered 



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