124 ILLUSTRATIONS OF THE 



whinJlone. This, however, is to be confidered 

 as embracing a period of great duration j and 

 it muft always be recolleded, that veins are 

 found of very different formation ; fo that when 

 we fpeak generally, it is perhaps impoffible to 

 ftate any thing more precife concerning their an- 

 tiquity, than that they are pofterior to the llrata 

 and that the veins of whinftone feem to be the 

 mofl recent of all, as they traverfc every other. 

 123. In the fourth place, with refpedl to 

 time, we muft clafs the facfls that regard the de- 

 tritus and wade of the land, and mull carefully 

 diftinguilh them from the more ancient pheno- 

 mena of the mineral kingdom. Here we are 

 to reckon the fhaping of ail the prefent inequa- 

 lities of the furface ; the formation of hills of 

 gravel, and of what have been called tertiary llra- 

 ta, confining of loofe and unconfolidated mate- 

 rials ; alfo colledlions of fhelis not mineralized, 

 like thofe in Turaine ; fuch petrifadions as 

 thofe contained in the rock of Gibraltar, on the 

 coaft of Dalmatia, and in the caves of Bayreuth. 

 The bones of land animals found in the foil, 

 fuch as thofe of Siberia, or North America, are 

 probably more recent than any of the former *. 



_ J* 



124. Thefe phenomena, then, are all fo many 

 marks of the lapfe of time, among which the 



principles of geology enable us to dillinguilh a 



* 



certain 



* Note xxii. 



/ 



