AGE OF REPTILES. 



245 



earth was quite universally warm and genial, as is shown 

 by the wide diffusion of certain plants and animals, even 

 into the arctic regions. The vegetation, therefore, was 

 luxuriant, consisting largely of cy cads, conifers, and tree- 

 ferns, with some palms, lilies, etc. There were also equi- 

 setums and club-mosses. In Fig. 144 is represented the 

 vegetation of this period. In many localities the luxuri- 

 ant vegetation was packed down in beds of coal, as in 

 the Carboniferous period. There are localities of this 

 kind in Europe, in Great Britain, in China, in India, and 

 in Virginia in this country. Coal can be made of vege- 

 table fibre at any period if those circumstances are pres- 

 ent which I have stated to be necessary in the chapter 

 on the Coal-making age. 



350. Portland Dirt-bed. In the island of Portland, 

 and in some of the adjoining counties of England, there 

 have been found the remains of an ancient forest of the 

 Oolitic, or Jurassic period, lying between the strata. 

 This so-called Portland dirt-bed is composed of a bluish 

 loam, which contains stumps and roots of trees petrified, 

 as represented in Fig. 145. There are strata of rock 



\B 



Fig. 145. 



above and below ; those below, A, being mostly marine 

 limestone, and those above, C, being, on the other hand, 

 fresh-water limestone. The rocky strata and the dirt- 

 bed, you see, are all parallel, but not horizontal. They 

 were horizontal when they were formed, but have all in 

 some way been tilted up together. This tilting, howev- 

 er, is only found in some localities, the horizontal posi- 



