Feather stonhaugK's Geological Report. 15 



The moment such an individual begins to think of the cause 

 which could have produced this agreement betwixt pebbles 

 found in such dissimilar situations, he enters upon the study 

 of geology. This is one of its first and most important lessons, 

 and the solution to the inquiry will be found to be the key 

 to similar phenomena, in situations still more extraordinary. 

 To trace these rounded pebbles to their native rocks, often 

 hundreds of miles distant from them, they must be compared 

 with other pebbles strewed along the whole distance to the 

 original masses from whence they were detached ; and then 

 comes the great question of the cause which gave them the 

 pebble form, and which brought them there. Another im- 

 portant question would now suggest itself to him, whether the 

 whole substance of the crust of the earth is one solid mass of 

 materials resembling those which appear on the surface. Al- 

 though he had observed no mineral differences in the rocks 

 he had examined, yet if the territory upon which he trod fur- 

 nished several strata or beds superimposed upon each other, 

 he might find some indications of those strata either in the mural 

 escarpments on the sea-coast, in the valleys and ravines inland 

 which had been worn by the action of rivers, or in the fis- 

 sures which had been caused by any natural agents. In such 

 situations he would often find the mineral structure of the 

 rocks corresponding on the opposite sides of the valleys and 

 of rivers, in consequence of the strata having been divided, 

 and the same beds presenting themselves on each bank. 

 When fully satisfied that there were various mineral beds 

 lying beneath the arable soil on the surface containing the 

 rolled pebbles, he would be still more anxious to learn the 

 nature of all the beds lying beneath those he had examined. 

 At length, extending his investigations, he would find that the 

 same beds, containing the same kinds of fossil shells, were laid 

 upon each other in the same order of succession at very dis- 

 tant points, and that where he could recognise one bed, it 

 would serve as a key to the probable existence of other asso- 



