356 Edward Merrick — The River Tyne Drainage Area. 



Strata. 

 Magnesian Limestone 

 Yellow Sands 

 Coal-measures 

 Millstone Grit 



Though, the outcrop of the Millstone Grit has been arched up some 

 2,500 feet higher at Cross Fell than in the Tyne Valley, yet the 

 change in level of the land surface and dip of the strata is so gradual 

 that it is similar to the passage of horizontal strata into a monoclinal 

 fold which gradually breaks into a fault along the Tyne Valley. On 

 the other hand, when examining the Geological Survey maps of the 

 older rocks forming the inlier below Cross Fell, it is observed that 

 they are bounded on the north by normal faults throwing north, and 

 on the south by normal faults throwing south. 



The Carboniferous rocks on the top of this inlier are very slightly 

 disturbed, being almost horizontal, while those in the synclines 

 flanking it (as near Haltwhistle and Fourstones) are rolling and 

 associated with short and sharp anticlinal and synclinal folds. These 

 disturbed rocks lie at a lower elevation than the surface of the inlier, 

 giving it the appearance of a buttress against which they have been 

 pressed ; but as they occur some miles north of the inlier, this 

 appearance may be deceptive. The above description would almost 

 fit the Craven area if Ingleborough were put for Cross Fell, and the 

 other place-names also changed. 



The drainage system of the Tyne has been described above as due 

 to the denudation of a composite plane of rock. Because the close 

 connexion between the field structure and drainage supports this 

 view, this river system is therefore not regarded as one superimposed 

 upon it by the denudation of a younger deposit now completely 

 removed. Yet if this area were ever covered by a deposit of fairly 

 uniform thickness, laid upon this rock, surface as an unconformity, 

 the resulting drainage would still be much the same as it is now, 

 provided that this young deposit were older than the earth movements 

 already described. 



The denudation of the area is so closely related to the outcrops of its 

 rocks (nearly all of which belong to the younger Palaeozoic period) 

 that it has the appearance of continuous action during the later 

 periods, especially so as the most elevated area is most eroded. That 

 this may not be the case is seen on comparing it with a younger area 

 with greater denudation. 



A suitable area for such comparison is the Weald, where post- 

 Cretaceous movements arched the Chalk into an anticline now 

 denuded. When a line of correlation was drawn as an anticline 

 connecting the two escarpments, its height above the present 

 surface was termed the "Geological Elevation" of the Chalk by 

 Mr. W. Hopkins. This is a height of some 2,500 feet, and by a happy 

 chance the same height that the Millstone Grit on Cross Fell has 

 been arched above its outcrop in the Tyne Valley. In the Weald the 



