AN ANCIENT DELTA. 
341 
between the known superficial surface of the Weal- 
den, and the deltas of some modern rivers. As- 
suming that the occurrence of the Wealden strata 
at Beauvais is estiiblished, this eminent geologist 
computes that the remains of the delta of the 
Iguanodon period, are from west to east, or from 
Lulworth Cove, to the boundaries of the Lower 
Boulonnois, about ^300 miles ; and from north-west 
to south-east, or from Whitchurch to Beauvais, 
220 miles ; the total de])th or thickness being about 
2000 feet.* This but little exceeds the modern 
deltas of the Ganges, and tlie Mississi])])i ; and is not 
eipial to that of the Quorra, or Niger, which forms 
a surface of 2.5,000 square miles, being equal in 
extent to one half of England, t 
We have no data from which to calculate the 
probable duration of the Iguanodon epoch ; it is, 
however, manifest that no brief period could have 
sufficed for that profuse evolution of animal life, of 
which we have such positive evidence in the or- 
ganic remains. It may here, too, be remarked, that 
the vegetables and animals of this era, like the forest 
of Portland, denote a tropical climate, and belong 
to species and genera, wholly unknown ; and, as we 
have elsewhere observed, the fossil bones of the 
ovi])arous quadnqieds are so enormous, that it is even 
difficult to believe the evidence of our senses, when 
* Geology of Hastings, p. 58. 
-f- Ibid. Strata containing marine remains, with iron ore, have been 
observed between the upper beds of the oolite and the chalk, in the 
department of the Haute Saone ; near Gander, in the Brisgau ; and in 
Poland : they are supposed, by Mr. De la Beche, to have been formed 
in the sea during the Iguanodon era. — Man. Gcolog. p, 303. 
z .3 
