INVOLUTIONS. 101 



to occupy immense hollows in the primitive rocks. The 

 old red sandstone fills ^up the hollows of the transition, and 

 occasionally of the primitive rocks. The independent coal 

 formation is found occupying the hollows of the preceding 

 groups. The hollows of these different formations have been 

 still farther filled up, by the numerous series of beds con- 

 nected with chalk and gypsum ; and, at last, we come to the 

 alluvial deposits, which at present are contributing to fill up 

 existing inequalities. 



These changes which have taken place, have every where 

 diminished the height of mountains, filled up lakes, and in- 

 creased the quantity of dry land. We may therefore safely 

 draw the conclusion, that, along with the increase of dry 

 land, there musthave been a proportional diminution of aqua- 

 tic animals and plants, and a corresponding increase of those 

 which inhabit the land *. There is likewise reason to con- 

 clude, that, amidst these vast revolutions, so many altera^ 

 tions must have taken place in those physical conditions, on 

 which the life of animals depends, that multitudes must 

 have been annihilated with every successive change. The 

 increase of land, by this process of upfilling, and the reduc- 

 tion of the number of mountains supporting glaciers, must 

 have altered greatly the temperature of the globe ; and, in 

 every region, increased the difference between the heat of 

 summer, and the cold of winter, by promoting the intensity 

 of each. This change of temperature may have been some- 

 what modified by the progress of vegetation in the different 

 periods, by the formation of volcanic land, and the heat 

 communicated to the air by volcanic fire. It is impossible 

 to estimate all the effects which these changes may have pro- 



This view of the matter is countenanced by the circumstance, that the 

 remains of aquatic plants and animals are more abundant in the rocks of the 

 different ages, than those belonging to the inhabitants of the land. 



