z6o THEORY of the EARTH. 



means of heat, and hardened from a ftate of fufion. But this 

 propofition is equally to be maintained from principles which 

 are mechanical. The ftrata of the globe, befides being formed 

 of earths, are compofed of fand, of gravel, and fragments of 

 hard bodies, all which may be confidered as, in their nature, 

 fimple ; but thefe ftrata are alfo found compofed of bodies 

 which are not limple, but are fragments of former ftrata, which 

 had been confolidated, and afterwards were broken and worn 

 by attrition, fo as to be made gravel. Strata compofed in this 

 manner have been again confolidated ; and now the queftion is, 

 By what means ? 



IF ftrata compofed of fuch various bodies had been confoli- 

 dated, by any manner of concretion, from the fluidity of a 

 diffolution, the hard and folid bodies muft be found in their 

 entire ftate, while the interftices between thofe conftituent parts 

 of the ftratum are filled up. No partial fracture can be con- 

 ceived as introduced into the middle of a folid mafs of hard 

 matter, without having been comnumicated from the furround- 

 ing parts. But fuch partial feparations are found in the mid- 

 dle of thofe hard and folid maffes ; therefore, this compound 

 body muft have been confolidated by other means than that of 

 concretion from a ftate of a folution. 



THE Spanim marble already defcribed, as well as many con- 

 folidated ftrata of filiceous gravel, of which I have fpecimens, 

 afford the cleareft evidence of this fact. Thefe hard bodies are 

 perfectly united together, in forming the moft folid mafs ; the 

 contiguous parts of fome of the rounded fragments are inter- 

 laced together, as has already been obferved ; and there are par- 

 tial flirinkings of the mafs forming veins, traverfing feveral 

 fragments, but perfectly filled with the fparry fubftance of the 

 mafs, and fometimes with parts of the ftone diftinctly floating 

 in the tranfparent body of fpar. Now, there is not, befides 

 heat or fufion, any known power in nature by which thefe ef- 

 fects might be produced. But fuch effects are general to all 



confolidated 



