444 



THE WONDERS OF GEOLOGY. Lect. IV. 



progress, they sank down, and became imbedded. The 

 phenomena here contemplated cannot, I conceive, be satis- 

 factorily explained upon any other grounds ; and the 

 source of the mighty stream which flowed through the 

 country of the Iguanodon must, therefore, like that of 

 the Mississippi, have been hundreds, perhaps thousands, 

 of miles distant, from the delta accumulated in the course 

 of ages at its mouth. 



Such was the country of the Iguanodon — a country, 

 which language can but feebly portray, but which the 

 magic pencil of a Martin, by the aid of geological research, 

 has rescued from the oblivion of the past, and placed before 

 us in all the hues of nature, with its appalling dragon- 

 forms, its forests of palms and tree-ferns, and the luxuriant 

 vegetation of a tropical clime.* 



47. Sequence of geological changes. — Let us now 

 review the sequence of those stupendous changes, of which 

 our examination of the geological phenomena of the south- 

 east of England has afforded such incontrovertible evidence. 

 From the facts brought before us, we learn that at a period 

 incalculably remote, there existed in the northern hemi- 

 sphere an extensive island or continent, possessing a climate 

 of such a temperature, that its surface was clothed with 

 coniferous trees, arborescent ferns, and plants allied to the 

 Cycas and Zamia ; and that the ocean which washed its 

 shores was inhabited by turtles, and marine lizards of 

 extinct genera. This country suffered a partial subsidence, 

 which was effected so tranquilly, that many of the trees 

 retained their erect position, and the cycadeous plants, and 

 a considerable layer of the vegetable mould in which they 

 grew, remained undisturbed. In this state an inundation 

 of fresh water covered the country and its forests, and depo- 

 sited upon the soil and around the trees a calcareous mud, 



* See the Frontispiece; an engraving on steel, from an original 

 painting by John Martin, Esq., K. L. 



