GEOLOGICAL SKETCH 293 



I have before mentioned an old fort that stood near the 

 Black Mountain. A gentle stream flowed past the grim 

 old fort. Its waters were shallow and remarkably clear. 

 Its bed was composed of sand and pebbles all in con- 

 tinual motion, and from the bank it was easy to follow 

 the changes that occurred as all the grains of sand were 

 swept onward in their long journey to the sea. 



Grain after grain the little crystals rolled along 

 as though they were all racing for the ocean. But 

 there was some method, some system in their roll. 

 The smallest fragments were swept off the bed of the 

 stream to be dashed about in the gentle eddies, but 

 the larger fragments offered a more stubborn resist- 

 ance. The current would seize one of these larger 

 granules, hurry it onward, turn it over and over 

 amongst its fellows so as to smooth off its sharp edges 

 and projections. It is swept on, but soon meets an 

 obstacle in its path, and there fixing itself, it defies the 

 stream. Smaller granules are piled up against it, and 

 an ever-increasing resistance is offered to the waters. 

 The mass grows larger, it can now no longer withstand 

 the onset of the current, it is torn up and swept 

 onward to recommence the endless roll. The white 

 crystals of quartz and felspar have a poor chance in 

 their contest with the stream ; wherever they turn, 

 however they roll, the water can seize the little bulky 

 crystal and ever roll it on. It is the sparkling grains 

 of mica, though light and fragile, that fight with the 

 most effect against the current, for they glide in 

 between the larger pebbles and offer their sharp edges 

 to the stream. So does each grain of sand, some 

 slowly, some swiftly, roll along the river bed. 



Not only were all the little sand-grains rolling, but 



