NATURAL HISTORY OF CREATION. 67 



we liiid the masses of dry land increase in number and 

 extent, and begin to bear an amount of forest vegetation, 

 far exceeding that of the most sheltered tropical spots of 

 the present surface. The climate, even in the latitude 

 of Baliin's Bay, was torrid, and perhaps the atmosphere 

 contained a larger charge of carbonic acid gas (the 

 material of vegetation) than it now does. The forests 

 or thickets of tiie period included no species of plants now 

 known upon earth. They mainly consisted of gigantic 

 shrubs, many of which are not represented by any exist- 

 ing types, while others are akin- to kinds which, in tem- 

 perate climes at least, are now only found in small and 

 lowly forms. That these forests grew upon a Polynesia, 

 or multitude of small islands, is considered probable, 

 from similar vegetation being now found in such situa- 

 tions within the tropics. With regard to the circum- 

 stances under which the masses of vegetable matter were 

 transformed into successive coal strata, geologists are 

 divided. From examples seen at the present da}^, at the 

 mouths of such rivers as the Mississippi, which traverse 

 extensive sylvan regions, and from other circumstances 

 to be adverted to, it is held likely by some that the vege- 

 table matter, the ivubbish of decayed forests, was carried 

 by rivers into estuaries, and there accumulated in vast 

 natural rafts, until it sunk to the bottom, where an over- 

 layer of sand or mud would • prepare it for becoming a 

 stratum of coal. Others conceive that the vegetation 

 first went into the condition of a peat moss, that a sink 

 in the level then exposed it to be overrun by the sea, and 

 covered with a layer of sand or mud ; that a subsequent 

 uprise made the mud dry land, and fitted it to bear a new 

 forest, which afterwards, like its predecessor, became a 

 bed of peat ; that, in short, by repetitions of this process, 

 the alternate layers of coal, sandstone, and shale, consti- 



c 2 



