GEOLOGICAL TOUR. 19 



and multitude of chemical and organic combi- 

 nations carried on in the great laboratory of 

 nature. 



Eaces of beings belonging to an epoch of 

 incalculable duration lived and perished, leaving 

 their exuviaB in the solid rock as memorials of 

 their existence. These were succeeded by others 

 of different forms and habits, who also becoming 

 extinct, bequeathed to subsequent times a history 

 of themselves and their age, written, like that of 

 their predecessors, in the durable materials of the 

 globe ; they in their turn were succeeded by others 

 of dissimilar forms ; these again by others ; so 

 that the mutations which geological inquiries 

 disclose may truly be considered as the history of 

 life and its metamorphoses. 



Commencing our tour at the Land's End, and 

 proceeding eastwards along the shores of Corn- 

 wall and Devonshire, the remarkable circumstance 

 attracts our attention, that the whole of the coast, 

 with certain exceptions, is formed of the old red 

 sandstone, to which the term Devonian strata is 

 applied, but which sparingly occurs in any other 

 district of England, while it constitutes a large 

 portion of the central and northern divisions of 

 Scotland and a considerable portion of Wales. 

 Associated with this prevailing formation we find, 

 moreover, granite rocks, which form the Land's 

 End; serpentine, which constitutes the Lizard; 

 mica and chlorite schists at the promontory of 

 Start Point, and several instances of trap and 

 porphyry occurring at intervals. Proceeding 



C 2 



