Mr Ifujjh Miller on River- Terraciiifj. 295 



had worked the waterfall backwards through boulder okay for 

 more than 200 yards. In ten months it had extended its new 

 and deeper course to the foot of a rocky ravine.* But there, 

 as a separate impulse, its progress was checked. It added a 

 little to the length of the ravine, and something, perhaps, to 

 its steepness and liability to erosion, but the rock was a 

 medium in wliich the individuality of the impulse was 

 absorbed and lost. To this subject, however, we shall return. 

 In continuous boulder clay, or soft tertiary deposits, there is 

 no reason to doubt that impulses of the kind may be pre- 

 served for a considerable distance. The terraces thus pro- 

 duced, like the delta terraces into which they expand, are of 

 equal height on opposite banks. 



Gorge Terraces. 



The " gorge terrace " of Hitchcock is one of which the 

 writer has had no experience. It is stated to occur either 

 above or below gorges, and to be " intermediate between the 

 lateral and the delta (fan) terrace." It is higher than the 

 lateral terrace, and in issuing from the gorge (or in rising up 

 to it) seems to slope away to the normal elevation, somewhat 

 after the "fashion of a fan terrace. It does not appear, how- 

 ever, that there is any necessary room for the distinction 

 between lateral terraces and gorge terraces. In narrowed 

 positions streams rise higher, and, if formed and preserved at 

 all, their terraces must be higher also. Thus during the 

 Morayshire floods the heights attained by the river Findhorn, 

 as given by Dick Lauder, may be tabulated as follows : — 



At Eandolph's Bridge, after rising above the lip of the 

 * The ilovayshire Floods, 2d Edition, pp. 74-76. 



