BY HTJGH MILLER. 313 



of equal width throughout. Look along North Tynedale from 

 the high ground between "Wark and Bellingham, and it appears a 

 hroad and gently concave basin, as shallow in proportion to its 

 width, you might say, as the hollowed half of an oyster shell, or 

 even more so. Such valleys are evidently very far removed from 

 the deep, steep-sided trenches which rivers cut for themselves 

 when travelling through rainless districts, as is well known in the 

 case of the narrow profound canons of the Colorado, which some- 

 times exceed a mih in sheer depth. Eains and frosts have evidently 

 been long at work upon these far- withdrawing slopes. Tynedale 

 has in truth reached an advanced stage of excavation ; in com- 

 mon with all our large valley-systems it is greatly older than 

 the glacial period. '' It may be safely said," writes Prof. Eam- 

 say, *' that before the glacial period the river-systems of Britain 

 were very much the same as now."* So deeply excavated is it 

 into the body of the country, belonging, indeed, to a physical 

 order of things when Britain stood higher out of the sea, that 

 were the whole valley cleared from the glacial drifts that thickly 

 line its bottom, an arm of the sea would extend far inland ; how 

 near to Hexham Bridge I will not venture to say ; and in the 

 greater part of the valley above it, the river, which now flows off 

 and on its old channel, would run at a considerably lower level. f 



The same great breadth which I have remarked upon, is seen 

 in its main tributaries ; and seems in them altogether dispropor- 

 tionate to their length. The Erring Yalley, entering ]S"orth Tyne, 

 actually shews for its four miles of length (for above Hallington 

 its stream is nothing) one and a half of breadth. | Erring and 

 Houxty Burns, in North Tyne ; Allendale and the vale towards 

 Gilsland, — used in part by the Tipalt, in South Tyne ; are exam- 

 ples of this surprising breadth. 



Such are the main valleys, the great highways of transport for 



• Physical Gcol. and Geog. of Gt. Britain, 5th Edition, p. 630. 



f Prof. Ramsay in tho volume just referred to nliudos to the Tyne ns "this preglacial 

 river," and quotes a description of a lower reach of its old course. All the places I know, 

 from Falstone downwards, where the river runs on rock, are points nt which it has failed 

 to recover this ancient channel. 



% It is worth remarking that this valley docs not contain within it, so far as can be 

 seen, a single sandstone massive enough to build with. 



