W E A 



prodigious magnitude, that the ex- 

 isting animal creation presents us 

 with no fit objects of comparison. 

 Imagine an animal of the lizard 

 tribe, three or four times as large 

 as the largest crocodile, having 

 jaws, with teeth equal in size to 

 the incisors of the rhinoceros, and 

 crested with horns; such a creature 

 must have been the Iguanodon !" 

 WEALD-CLAY. (Argile veldienne of 

 Brongniart ; Wealdthon, Germ.) 

 A tenacious blue clay, containing 

 subordinate beds of sandstone and 

 shelly limestone, with layers of 

 septaria of argillaceous ironstone, 

 forming the subsoil of the wealds 

 of Sussex and Kent, and separating 

 the Shanklin sand from the central 

 mass of the Hastings beds. Dr. 

 ManteWs Geology of the South- east 

 of England. 



The "Weald-clay contains argil- 

 laceous iron-stone, occurring in 

 regular beds. This ore of iron 

 was so valuable, when it was the 

 practice to use wood-charcoal for 

 smeltiDg, that furnaces were for- 

 merly numerous along the verge of 

 the Weald. The thickness of the 

 Weald-clay is estimated at 150 or 

 200 feet in Western Sussex. 

 WEA'LDENFOEM'ATION. } TheWealden 

 WEA'LDEN STB' ATA. ) formation, 

 group, or strata, have been sepa- 

 rated into three principal divisions. 



1. The Wealden clay, above de- 

 scribed. 



2. The Hastings sands: grey, white, 

 yellow, and reddish-brown sands, 

 and friable sandstone, passing into 

 limestone. 



3. The Purbeck beds, called also 

 Asburnham beds, consisting of grey 

 limestone, alternating with blue 

 clay and sandstone shale. The 

 whole of these are freshwater or 

 fluviatile deposits. The wealden 

 is covered by the marine cretaceous 

 system, and reposes upon the upper- 

 most member of the oolite, which 

 is also a purely marine deposit. 



[ 460 ] W E A 



This intercalation, says Sir C. Lyell, 

 of a great freshwater formation be- 

 tween two others of marine origin 

 is a remarkable fact, and attests, in 

 a striking manner, the great extent 

 of former revolutions in the position 

 of sea and land. From these and 

 other data, he says, it seems a legi- 

 timate deduction that the marine 

 formations of an antecedent period 

 (that of the oolite) had become 

 land throughout a portion of the 

 space now occupied by the South 

 of England and the opposite coast 

 of France ; and that this land then 

 sunk down, with its forests, and 

 became submerged beneath the 

 waters of a great river. The 

 country may then have continued 

 to subside, until a thickness of two 

 thousand feet of fluviatile sediment 

 had been gradually accumulated; 

 and this deposit, or delta, by a 

 continuation of the same depressing 

 operations, may, in its turn, have 

 become buried deep beneath the 

 ocean of the chalk. Dr. Mantell 

 may be considered the great geo- 

 logical champion and hero of the 

 Wealden, for to his indefatigable 

 exertions in that field, are owing 

 some of the most splendid disco- 

 veries in paleontology. Until the 

 appearance of Dr. Mantell' s works 

 on the Geology of Sussex, the pe- 

 culiar relations of the sandstones 

 and clays of the interior of Kent, 

 Sussex, and Hampshire, were en- 

 tirely misunderstood. No one sup- 

 posed that these immense strata 

 were altogether of a peculiar type, 

 and interpolated amid the rest of 

 the marine formations, as a local 

 freshwater deposit. Prof. Phillips. 

 Dr. Mantell observes that the 

 Wealden may be considered as 

 covering an area 200 miles in 

 length, from west to east, and 220 

 miles from north-west to south-east, 

 the total thickness averaging about 

 2000 feet. Of this series of deposits, 

 clays, or argillaceous sediments, 



