MINERALOGY OF THE REDHEAD. 



341 



The Brothick Bum appears to have formed its 

 own channel in the soft alluvial strata through 

 which it flows. The bottom of the valley is of 

 considerable extent, when compared with the nar- 

 row bed which contains the river in the drought 

 of summer ; but when the stream is swollen with 

 autumnal floods, or choked with the ice and snow 

 of winter, the valley itself, unless prevented by 

 artificial barriers, would then become the bed of the 

 river, as its smooth surface indicates it at one 

 time to have been* When the present bed of the 

 river shall have acquired sufficient depth to contain 

 all the water which at any season flows in it, then 

 a new flat will be formed on each side, and the 

 banks will present that terraced appearance which 

 may be observed on the sides of many streams 

 which have scooped out their channels in loose and 

 soft materials. The opposite banks of rivers, may 

 always be expected to be parallel where the mate- 

 rials of which they are formed are similar in com- 

 position * having obtained such a relation at first, 

 they have been exposed to the influence of the 

 game destructive agents in every subsequent period. 



The beds of gravel and sand, which form the 

 banks of the Brothick, are connected with similar 

 depositions, which occur in the neighbourhood. 

 Near the Town of Aberbrothick, there are nu- 

 merous hills of gravel, which appear to have a 

 north-westerly direction. The gravel is frequent- 

 ly coarse, and consists of rounded masses of granite, 



VOL. II. 7. 



