302 " TYNEDALE ESCARPMENTS; 



stream-cut notches filled \nth. boulder clay, and the relations of 

 the drainage, which dates from an cai'lier period, seem to me 

 to point unequivocally in this direction.* 



5, Formation of Outcrop Terraces hy Rivers. — Attempts have 

 been made to trace the flights of limestone terraces that border the 

 Yorkshire dales to the immediate action of their rivers. This 

 ^'iew, however, is rendered quite untenable when the terraces are 

 found continuous with far-stretching series of ridges. It is of the 

 essential nature of ridges to become step-like or terrasse when 

 disposed in a common slope, and it is manifest that rivers cannot 

 possibly have themselves originated features that range, not only 

 alongside dales, but over heights and even water-sheds. Among 

 the Tynedale streamlets, one may certainly notice a tendency to 

 cut undenieath the more solid beds, here and there along softer 

 planes, lea^'ing faint local indications of terraces ; or more often 

 little crescent-shaped recesses, like the dent of a heel on the bank, 

 prettily overhung by trees and mantled by greenery. Such, — 

 veiy different from the "steps and stairs" we now fijid, — may 

 have been the beginnings of dale-terraces : but in valleys whose 

 far-withcbawing sides have overlooked the river in ages much 

 anterior to the glacial period this origin is a very remote ante- 

 cedent indeed. The valleys must have been widened otherwise 

 than by the river. What has widened them ? 



6. Tliconj of Origin by Atmospheric Waste. — At the end of last 

 century, Hutton, the Father of Physical Geology, wrote some 

 remarkable words about the Edinburgli Crag-and-Tail. " The 

 isolated Crag and Tail of Edinburgli," he said, *' hold their par- 

 ticular form from the joint operation of two different causes; one 

 is the extent and casual shape of the . . . mass ; the other is the 

 degradation of tliat mass, which is wasted by the influences of 

 the atmosphere, though wasted slower than tlie strata in which 

 it is involved."! Hero we have the enunciation, clear and for- 

 cible, of a belief that purely atmosi)heric waste is able to lower 

 the whole face of a countiy just as it decays and crumbles away 



• Sec poKtco, p. 316. 

 t Theory of the Etirili, Vul. II., |>. 417. 



