( IIAPTER VI 



DETERMINATION OF ROCKS 



: HER field-geology is to be carried on rapidly and 

 in a generalised way, or slowly and in detail, the same 

 methods must be followed I have supposed the gcolo- 

 > have selected and reached his ground, and to 

 have made a few preliminary traverses to gain some 

 notion of the chief rocks and their arrangement. I 

 follow his subsequent operations. 



The brooks, ravines, sea-coasts, hillsides, valleys, and 

 mountains, the pits quarries, and rail way -cuttings, in 

 short every natural section or artificial exposure of the 

 rocks, will be carefully examined, and the observation* 

 made will be registered in notebook or map at the time. 

 In the course of these rambles three points will h. 

 be settled : first, the lithology and distribution of the 

 rocks ; second, their probable or actual geological horizon 

 or date ; third, their position with regard to each other, 

 that is, the geological structure of the district 



The determination of the nature of the rocks is 

 obviously the first question which must be dealt with. 

 And here it must be remembered that the term rock is 

 applied in geology indifferently to all kinds of naturally- 

 formed stones or deposits, even to peat, blown sand. 



