THEORY OF THE EARTH. 21 



are in the ancient strata even in greater number 

 and better defined. 



But these primitive masses have also under- 

 gone other revolutions since the formation of the 

 secondary strata, and have, perhaps, given rise 

 to, or at least have partaken of, some of those 

 changes which these strata themselves have expe- 

 rienced. There are actually considerable portions 

 of the primitive formations uncovered, although 

 placed in lower situations than many of the secon- 

 dary formations ; and we cannot conceive how it 

 should have so happened, unless the primitive 

 .strata in those places had forced themselves into 

 view, after the secondary strata had been formed. 

 In certain countries, we find numerous large blocks 

 of primitive substances scattered over the surface 

 of secondary formations, aud separated by deep 

 valleys, or even by arms of the sea, from the peaks 

 or ridges from which they must have been derived. 

 We must necessarily conclude, therefore, either 

 that these blocks have been ejected by eruptions, 

 or that the valleys (which must have stopped their 

 course) did not exist at the time of their being 

 transported ; or, lastly, that the motions of the 

 waters by which they were transported, exceeded 

 in violence any thing that we can imagine at the 

 present day*. 



* The Travels of Saussure and Deluc present a multi- 

 tude of facts of this description. These geologists imagined, 



