﻿Vol. 6 1.] OF THE NORTHUMBEELAND AND DURHAM COALFIELD. 



73 



Geological Survey in as accurate a manner as possible, and the maps 

 appended to the present paper (figs. 7 & 9, pp. 82 & 85, & PI. IX) 

 indicate the parts of the country where the rock comes to the 

 surface. 



From some of the areas now bereft of a covering of clay, the 

 superficial Glacial deposits have undoubtedly been removed, and 

 the rock has been exposed along the courses of several of the post- 

 Glacial streams, which have in many cases cut their way through 

 rock rather than through Boulder- Clay. 



The surface-deposits lie arranged in the valleys formed before the 

 Glacial Period, and in many of them reach a considerable depth. 

 They thus fit upon and level up the pre-Glacial inequalities of the 

 country, being thick along the hollows that existed before the Ice- 

 Age, and rising to a considerable height along their sides. The 

 deepest borings through these deposits are thus all found to lie 

 along the valleys, and, as a rule, to decrease gradually in depth as 

 the higher ground along the flanks is reached. By mapping all the 

 available sinkings it has been found possible to obtain the lie of 

 the rock-surface, and a true idea of the pre-Glacial surface of the 

 country, provided that there have been no extensive differential 

 movements since pre-Glacial times. The following are some of the 

 deepest borings through the superficial deposits. It will be seen 

 that many of them go to a considerable depth below sea-level before 

 reaching the rock-surface, and that the maximum thickness attained 

 by these deposits, so far as the data that I have been able to collect 

 prove, is 233 feet at Newton Hall, Framwellgate, about 2 miles 

 north of Durham. It is, however, very probable that they reach 

 as much as 300 feet in the valley of the ' Wash.' 



1 



Locality. 



Valley. 



Height 

 above 



sea-level. 



Thickness op 

 superficial 

 deposits. 



Height op 

 hock-surface 



ABOVE, or 



DEPTH BELOW, 



SEA-LEVEL. 



j Burdon Main 



1 Norwood New Pit 



Blaydon 



Wallsend 



Tyne 



'Wash' 



Tyne 



Tyne 



Feet. 



50 



16 



20(?) 



72 

 100 



50 



70 



28 



'55 



86 

 105 

 230 

 210 (?) 

 300 (?) 

 295 



Feet. 

 191 

 156 

 145 

 170 

 193 

 143 

 145 

 90 

 102 

 123 

 116 

 233 

 186 

 220 (?) 

 202 



Feet. 

 -141 

 -140 

 -125 



- 98 



Percy Main 



Sleekburn 



Chirton 



Cambois 



West Cbevington . . . 



Harton 



Cboppingtoa 



Newton Hall 



Netherton 



Whalton 



Bearpark 



Tyne 



' Sleekburn ' 



Tyne 



' Sleekburn ' 

 ' Sleekburn ' 

 ' Cleadon '... 

 ' Sleekburn ' 

 'Wash' 



Browney . . . 



- 93 



- 93 



- 75 



- 62 



- 57 



- 37 



- 11 



+ 24 

 -r 80(?) 

 + 93 



[Throughout this paper the 4- sign indicates tbat the rock-surface lies 

 above sea-level, the — sign that it lies below.] 



