Edward Merrick — The River Tyne Drainage Area. 297 



5. It would result in bringing younger rocks against increasingly 

 older ones on passing from east to west. (Fig. 2.) 



6. The strike of the rocks would follow the general trend of the 

 contour-lines as already described. 



7. Where the throw of the fault was small, the alteration in 

 direction of the lines of strike and contour-lines would also be small, 

 and they would still resemble ancient shore-lines through being nearly 

 concurrent with those in process of formation. 



8. The course of the main river would be concurrent with that of 

 the fault. (Fig. le.) 



The next step is to examine the surface and geological features of 

 the area to see if such disturbances and results have taken place. 

 Taking each of the above considerations in turn, it is found that — 



1. If the valleys of the Tyne area be imagined as being filled up 

 as high as the original surface of the junction-plane, the contour-lines 

 do then change their direction as mentioned. This reconstruction of 

 the surface contours can be done on the 1 inch contoured map by 

 joining the most easterly and southerly occurrences of the same 

 contour heights together by a line bounding them from the area on 

 which that height does not occur. 



Fig. 2. — Diagram of the strike in the strata in the same area as Fig. lc. 

 E = Later deposits. D = Permian. C, B, A = Carboniferous. 



2. The North Tyne and its tributaries are seen to flow in a direction 

 consistent with the above reconstruction. 



3. A watershed does run in this direction, which is the same as 

 that of the Corbridge Fold originally described by Professor Lebour. 



4. The lie of the rocks and the heights at which they outcrop are 

 changed. The Corbridge Fold and the extension of the Coal-measures 

 (with a southerly dip) along the Tyne valley are partial results of this 

 faulting. 



5. The Ninety Fathom Dyke, which runs generally east and west, 

 throws the Magnesian Limestone and Yellow Sands of the Permian 

 against the Coal-measures, and younger Coal-measures against older 

 Coal-measures, at its eastern exposure. Further inland the Stublick 

 Dyke commences, which brings the Coal-measures successively against 

 the Millstone Grit, Carboniferous Limestones, and Shales on proceeding 

 westwards. At the extreme west this junction-plane has been 

 lowered to such an extent that Triassic rocks were deposited upon it. 

 It must be pointed out, however, that at Cullercoats the present land 

 levels are the same on both sides of the Ninety Fathom Dyke, yet 



