SOME NORTH-OF-ENGLAND DYKES. Dall 
Tur Hespsurn Dyke. 
Interature. 
Winco, N.J. ‘Observations on the Geology of Northumberland 
and Durham,” Trans. Geol. Soc. vol. iv. (1827). 
Lzzovr, Prof.G.A. Outlines of the Geology of Northumberland 
(1878), p. 48. 
Ordnance Maps (1 inch). 105 8.E. and S.W. 
This dyke is described by Prof. Lebour as emerging from beneath 
the Magnesian Limestone near Cleadon, and passing in a W.N.W. 
direction by Hedworth and Hebburn to the Tyne at Walker, where 
it enters Northumberland. ‘There is, so far as | know, no exposure 
of this dyke at the surface now known; but Winch describes a 
quarry which was formerly worked about 1 mile north of the Boldon 
Hills. ‘The rock,” he says, “ was fine-grained, nearly black, and 
filled with small globules of milk-white chalcedony not bigger than 
a mustard-seed.” 
The course of this dyke, as marked on the Survey maps, has there- 
fore been traced by means of the data supplied by the numerous 
colliery workings in the district. Prof. Lebour regards the cele- 
brated Coley-Hill dyke, which was formerly worked on such an 
extensive scale to the west of Newcastle, as a continuation of the 
Hebburn dyke ; but as the former agrees very well in direction with 
the Tynemouth dyke, with which it has also very close petrological 
affinities, I am inclined to regard it rather as a continuation of the 
latter than of the former. When speaking of the relations of the 
dykes of Coley Hill, Walker, and Boldon, Mr. Winch says :—‘“ It is 
by no means ascertained that they are portions of the same dyke 
connected together below the surface, since no trace of that of Coley 
Hill could be discovered in the very extensive and ancient collieries 
of Montagu and Kenton, situated in its course at a short distance 
to the east of it; nor was the Walker dyke found in any other 
quarry.” 
The only locality where I have had an opportunity of examining 
B. Greyish black cinder, 12 yards. 
C. Greyish black cinder. 
