BY HUGH MILLEE, 319 



influences of the summer, to give us the beautiful vale of 

 JN'orth Tyne. 



I pass on to consider the features among the ' ' Eig-and-Fur" 

 that depend upon specialties of structure. 



It has been already sufficiently indicated that it is the compo- 

 site nature of these Carboniferous strata that occasions this diver- 

 sity into ridge and furrow. We may see the same, to a certain 

 extent, in the cliffy scaurs bared at the elbows of a winding 

 stream, when bands of sandstone and limestone separated by 

 shale exhibit their conduct under the weather, side by side. The 

 face of the shales, where bare, is almost invariably hollowed, 

 leaving the others projecting, and often so undermined by its 

 decomposition, as to have little chance of becoming weathered 

 themselves. 



2. Sandstone Escarpneyits . — Among the several escarpment- 

 forming beds the first in general importance, though less pro- 

 minent than the "Whinsill, are the sandstones. There is no one 

 line of sandstone outcrop rising into crags throughout its whole 

 length. Constantly varying in quality along their strike or 

 stretchy the thickest and compactest sandstones are apt to dete- 

 riorate within a short distance. The crags coincide with hard, 

 well-jointed developments. In the well-known Queen's Crag 

 the main rock consists of one almost seamless bed, twenty-five 

 feet thick, marked out into massive pieces by joints. Followed 

 castwai'd this mural cliff sinks down within a few yards into a 

 heathery bank ; and a quarry some distance on shews the stone 

 to have become divided up into easily separable pieces of the 

 handy size favourite with builders of dry stone dykes. In other 

 crags the change is yet more sudden and complete. About a 

 hundred yards cast of Colt Crag, near Watling Street, the sand- 

 stone has become so loosened that it can be dug with a spado, 

 and the feature has wholly sunk from view. In this case the 

 deterioration is probably due to the absence of the chemical bind- 

 ing principle.* 



* Some saiulstoncs sei luulcr wcnthoriiij;' ; surfjices catuii liy tlic woatlior miiy bo seen 

 glistening almost as if porcollauizcd, and much more liomogoncous tlian In tin." interior 

 of the stone. Tlic sandstone upon wliich Ihc l{omans liave left their wedye-marksi 



