384 



THE GEOLOGIST. 



A Wash oe Deift theough the Coalfields of Dueham. By- 

 Messrs. N. Wood and E. F. Boyd. — The course of an ancient river, to 

 which the paper related, differed from the courses of the Tyne and of the 

 Wear. It passed almost in a direct line from Durham to the river Tyne 

 at Newcastle. It was 93 feet below the present level of the Wear, ana 

 140 feet below the level of the foundations of the High Level Bridge, 

 which were 30 feet below the bottom of the river. Having, in the prose- 

 cution of their professional duties, had many opportunities of collecting 

 information of the particulars of the thicknesses of the covering of gravel, 

 sand, and clay spread over the surface of the coalfield of Durham more parti- 

 cularly, in various situations and under different circumstances, and having 

 had frequent opportunities of observing the effect of the abrasion of the 

 mineral strata of the districts, and especially of a particular wash or drift 

 in the coalfield of Durham which has denuded a considerable portion of 

 the coal-measures, the authors laid before the Association the results of 

 their experience. Premising that such a wash or drift can be traced 

 through the coalfield from the vicinity of the city of Durham to the 

 river Tyne at Newcastle, traversing a portion of the valley of the Wear, 

 passing Chester-le-Street, and following the valley of the river Team, and 

 terminating at the river Tyne, their communication consisted of a plan 

 of the district in question, and a series of sections showing the line of the 

 wash and the depth to which it extends, with various other particulars. 

 An examination of the different cross sections, particularly those nearest 

 to the river Tyne, will encourage the idea that the deepest portion of the 

 denudation was by the eastern side, and that the edges of the strata 

 nearest to that side are more upright arid abrupt. No trace of shells 

 whatever has been found in any part of its course, nor of bones or animal 

 remains. The pieces of shale which were observed entire and resting on 

 edge against the eastern side, as if recently broken from their stratified 

 bed, contained on examination the usual ferns and plants of the Carboni- 

 ferous series ; all the stones and pebbles in having their edges entirely re- 

 moved and rendered smooth, particularly those of harder character, bore 

 evidence of long exposure to the abrading influence of water in motion, 

 and whenever the bottom on which the diluvium rests was exposed, there 

 are unmistakable evidences that the water which carried the debris was in 

 motion and of great power. At the sinking of the Ouston pit, the first solid 

 strata met with after sinking through the 23| fathoms of clay and sand 

 was a strong freestone, the upper surface of which was furrowed with rough 

 and scored outlines and polished, as may be noticed in the exposed bed of 

 a mountain-torrent passing over a strong rock. The edges of the coal- 

 seams adjoining the denudation, as the Hutton seam by Harbour House 

 and Frankland, and the main coal-seam at Urpeth, were worn and rounded 

 off in some instances where the upper portion of the seam having been 

 tender had given way to the abrading action, whilst portions of that 

 nearer the floor remained, the intervening parts being filled up with clay 

 and boulders and broken pieces of coal. The contemplation of this re- 

 markable deposit suggests to the authors considerations of the following 

 character : — 1 . The extent and cause of opposition which the dislodged 

 waters of the ocean met with in their progress to their ultimate sea-level. 

 If the magnesian limestone hills of Boldon, Pensher, Houghton, Pitting- 

 ton, and Quarrington (superimposed over the coal-measures), formed as 

 decided a barrier as they now present. 2. The quantity of debris with 

 which they were charged, and the opportunity thus afforded them of de- 

 positing these by the action of gravitation, exercised during the above op- 

 position met with, until the silting process was completed up to the level 



