I iksi I BBAYfl is i in n-WORK .7 



of gr.t cd on the sides of valleys high abo\c t he- 



present streams, yet evidently themselves of flu\ 



red rude stone-implements of 



;i workmanship. In yet a third localr ; find 



a mass of clay, stuck full of stones with their surfaces 



cd and scratched like the rocks below a Swiss 



glacier will learn that these striated stones and 



the clay containing them have once likewise been under 



a sheet of ice. In short he will soon perceive ti 



one of the many varieties of superficial deposits 

 is a story to be made out, and that it is worth his 



or it 



Lastly, it may chance that the beginner is so situated 

 as to be able to watch the actual visible progress of geo- 

 logical changes .me may be by the margir 



occasional floods, and always bearing on- 

 ward past him its burden of mud from distant lulls No 

 rung in geological observation could he desire 

 h is supplied by a careful and methodical 

 of the operations < Its times of flood and 



of low water, the proportion of mineral substances in its 

 from month to month, the way in which the sedi- 

 >posed of, the action of the river on its banks, 

 here cutting down and there heaping up, the relation of 

 the form of the channel to the rocks through which it has 

 been cut, now a ravine, now a waterfall, here a rapid, 

 there a lake-like reach these and many other points in 

 the physics of a river furnish endless material of ever 

 fresh interest The stream has its moods like a living 

 two years of its operations are exactly alike, 

 always to have surprises in store for us, 

 G 



