Feather stonkaugfr 8 Geological feport. 87 



grow, are there in abundance, with their * Oots struck into the 

 black dirt; these stumps are also silicified. At Ludworth 

 cove (see diagram No. 9) these beds are at an inclination of 

 about 45 degrees. The thickness of this bed of black earth 

 furnishes some measure, though of an indefinite kind, of its 

 duration, since it must be considered as an accumulation of 

 vegetable matter formed subsequent to its elevation from the 

 sea. Granting to the forest lands of the United States the 

 entire duration of our own chronology, they do not show evi 

 dences of having accumulated vegetable matter to that extent, 

 and allowing for the luxuriance of vegetation consequent upon 

 the ancient climate, a very long period may at least be con 

 ceded for its accumulation. But the terrestrial level of this 

 bed was again changed, and a basin-like form given to it, for 

 the collection of fresh waters, which at various periods have 

 deposited lacustrine sediments, 1,000 feet thick, including the 

 whole wealden group. During the existence of this lake, a 

 new race of monstrous reptiles appears the iguanodon, which, 

 from the organic remains collected, appears to have abounded 

 there. Mr. Mantell, the discoverer of this fossil animal, has 

 named it thus from its analogy to the recent iguana, wkfch is 

 an omnivorous animal, and from various fossil bon^s he pos 

 sesses, has made a comparative proportional estimate of the 

 probable size of the individuals of some genera, of which 

 they formed a part, and it has resulted that they were seventy 

 feet long from the snout to the end of the tail, were near fifteen 

 feet in circumference, and that the tail was upwards of fifty- 

 two feet long. Besides this animal, the megalosaurus, with 

 more than one species of crocodile, and various fresh-water 

 fish, were inhabitants of the waters. The generations of 

 these animals were, however, to cease, for we find these fresh 

 water strata changing their character and becoming the floor 

 of the ocean, the whole cretaceous group, of marine origin, 

 and about 1,000 feet thick, being deposited upon them. This 

 was probably produced by a reaction of the cause which first 



