172 



REV. THOMAS BROWN ON THE OLD RIVER TERRACES 



&c, the work of running water flowing down the valley. Eighty yards further 

 up, the same bank (sketch 19) is laid open up to its whole height of 120 feet, 

 where, in one of the gullies, innumerable alterations of the same strata are 

 shown. The last 20 feet* at the top are particularly well seen, as also are the 

 50 feet at the base in Sketch 18. 



Now that this terrace was formed by river floods is shown by its connection 

 with similar deposits further down the stream. Those seen in Sketch 1 must 



Sketch 19. — Below the Castle of Monzie. 



have been a river formation from the slope of their surface down the stream, 

 and not only is their structure identical with that at Monzie, but — allowing for 

 the effects of partial denudation — they may be traced running on till the one 

 series actually meets and passes into the other, forming two stages of terrace c, 

 as in Sketch 12. 



But if these deposits were formed by river floods, a single glance at such a 

 section as that in Sketch 18 will satisfy every geologist that the running water 

 began its work at the bottom, down on the level of the present river bed. 

 When the first stratum was laid down, the running water had found the valley 

 cleared out down as low as it is now. Explain that matter how we may, these 

 old floods must have had the power of doing this ; beginning at the level where 

 the stream runs now, they could form a terrace, piling stratum above stratum, 

 up to the height of 120 feet, as far, indeed as the water was able to rise. 



It is plain, therefore, that if the analogy of our Scottish rivers will apply to 



* See Plate iv. fig. 4, showing the arrangement of the gravels and sands forming the upper portion 

 of the terrace. 



