Mr Huffli Miller on River- Terr aciruj. 279 



which it has passed, hut a bank along the base of which it 

 has been drawn. The running water in its circuits may be 

 likened to a scythe in its traverses along the edge of a field ; 

 there is a breadth of shorn stubble and a wall of standing 

 corn. Vertical strata in a stream-bed, as all observers know, 

 lie with their ends shaven off, like the strata that enter into 

 a plane of marine denudation on the sea-shore. If the banks 

 bordering the stream be of rock, and not too high, it may be 

 found that the planing process has been pursued before at a 

 higher level, and that there exists an upper plane of river- 

 denudation with the truncated ends of its floor overspread 

 with alluvium (Fig. 



Fig. 8. 



Pkmation — Tariet Burn, North Tyne. 



A, Stream ; B, Shales and Sandstones planed off at top ; C, Sand and Graved 



of— D, Alluvial Flat ; E, Bank. 



Still higher on the valley sides there may lie other plat- 

 forms, similarly planed and overspread. 



This process of cutting and levelling has been termed 

 planation.* 



Relation between the Travelling of River- Curves and 

 Formatio7i of Gravel. 

 The methods by which surfaces of planation become 



gradually doubled into a deep loop at the turn, the elbow of which was pushed 

 farther and further west until it at length burst over into a hollow leading 

 into the Eden. Since then it has deepened 40 feet below the level of its old 

 eastward valley, which remains with its empty flat and a selvage of higher 

 terrace to tell the tale. My friend, Mr David Burns, C. E. , first noticed this 

 old valley. He supposed it to have been choked with ice when the Irthing 

 was first forced to quit it. But the age of " ice-jams " seems to have been past 

 ere the occurrence took place, judging from what I have seen of the gravels, 

 and all the facts are well accounted for as above described. 

 * W, K. Gilbert, Geology of the Henry Mountains. 



