Edward Merrick — The River Tyne Drainage Area. 355 



Stratigraphical Evidence. 



1. In this area post- Carboniferous and post-Permian movements are 

 known to have given changing directions of strike and dip to the rocks. 

 Some of these movements are known to be pre-Permian, but owing to 

 the absence of Mesozoic rocks it is not known if the post-Permian 

 movements are also post-Mesozoic ones. Pre-Permian planing is 

 proved by the unconformity between the Carboniferous and Permian 

 formations, both in this and neighbouring areas. It is proved in 

 South Durham by borings at Bradbury Carrs and Elstob, while at 

 Conscliff the Magnesian Limestone is seen to rest upon Millstone Grit. 

 The Yellow Sands are so irregular that the occurrence of the 

 Magnesian Limestone upon the Millstone Grit cannot be held as 

 proving either overlap or erosion of the Yellow Sands. Permian 

 erosion is proved in the Eden Valley by the presence in the Brockrams 

 of Carboniferous Limestone pebbles which are regarded as coming 

 from the Cross Fell escarpment, thereby implying the pre-existence 

 of the Pennine Fault. The latest erosion of the Tyne area can only 

 be returned as post-Permian from the stratigraphical evidence of the 

 solid rocks. 



2. Evidence of these movements is found in the neighbouring areas of 

 the Rivers Eden and Tees, where the land sank below sea-level, then 

 rose again with some covering of Liassic deposits that now exhibit 

 signs of disturbance. The Pennine Fault, by disturbing the Triassic 

 sandstones, is an example of Mesozoic or later faulting which follows 

 an older line of weakness. 



In describing the main valley and the collecting areas on its flanks, 

 the difference in surface levels was attributed to the Stublick Dyke 

 and the Cross Fell Anticline producing undulations of a rock surface 

 composed of strata with a common trend. If such were actually the 

 case, then the highest elevations reached by the different strata on 

 its flanks should vary in the same manner as the difference in surface 

 levels of the rock surface. Such, indeed, is found to be the case. In 

 a paper entitled "A New Flora of Northumberland and Durham", 

 by Messrs. J. G. Baker and G. P. Tate, 1868, there is a geological 

 introduction by Mr. G. Tate. In this paper it is mentioned that the 

 rocks attain different elevations on the two banks of the Tyne, but 

 no explanation is given for this. There is also a botanical map 

 founded upon the river drainage, but nothing is said about the origin 

 of the watersheds. The highest recorded outcrop of the Permian 

 formation in Northumberland is that of the yellow sands (now 

 obscured) at Closing or Clousden Hill, Killingworth, near the 200 foot 

 contour-line. 



Dr. D. Woolacott states that the highest point on the Permian 

 escarpment in Durham is at Warden Law, which is 646 feet high. 

 From this height about 120 feet of sand and gravel must be deducted, 

 leaving 526 feet for the height of the rock surface. Other exposures 

 are near the 500 foot contour. 



It is noticeable that the older rocks in the west are more elevated 

 than the younger ones in the east, yet it does not necessarily follow 

 that they form an older part of the Tyne drainage area. 



