Mr. Tate on Basaltic Rocks. 213 



sandstone and yellow sand, in the cliff facing the sea, below 

 the Priory ; but it is not seen penetrating the Magnesian 

 Limestone belonging to the Permian Formation, which caps 

 the same cliff a little to the northward. It is twelve feet 

 wide, and has a direction of nearly S.E. to N.W. (S. 40 Q E.), 

 with a slope southward 85°. 



The Coaly Hill Dyke, which varies in width from seven 

 to twenty-one feet, has a general direction E.S.E. to 

 W.N.W. Buddie has described it*, and notices that the top 

 of it undulates and only occasionally comes to the surface. 

 The basalt dyke in the bank of the Ouseburn, near to New- 

 castle, and that at Simonside, in the county of Durham, seem 

 to be continuations of it. In Benwell Colliery it is two 

 hundred feet ; and in Walker Colliery, six hundred and 

 thirty feet below the Tyne level. The coal in contact with it 

 is reduced to a cinder. 



In Wallbottle Dene two small dykes, about thirteen feet 

 apart, appear in the high bank of the burn, with a direction 

 of east to west, and sloping north 78°, the one being five 

 feet and the other six feet wide. They cut through Coal 

 Measures. 



The Brunton Dyke, near North Tyne, is sixteen feet wide, 

 and cuts through Mountain Limestone beds, which are up- 

 cast on the north-east side twenty feet. Its direction is 

 nearly from north-east to south-west (N. 40° E.) ; it crosses 

 the South Tyne and passing Warmley, probably extends to 

 Whitfield, where a basaltic dyke is on the West Allen. 



The Lewis Burn Dyke, which has a long and somewhat 

 irregular course, but with a general direction of from W.S.W. 

 to E.S.E., is traceable from Short Cleugh on Lewis Burn, in 

 North Tynedale, to Troughend and Darden, in Redesdale, a 

 distance of twelve miles. At Short Cleugh, in the deep 

 gullies, worn out by water torrents, this dyke is exposed at 

 several points ; it widens as it descends and attains a breadth 

 of fifty feet : Mountain Limestone strata are cut through and 

 greatly disturbed ; on its south side sandstone beds are flat, 

 while on the other they are nearly perpendicular. A small 

 branch comes from the main trunk, and is seen on the hill-side. 



The phenomena described suggest some theoretical ques- 

 tions — What is the origin of the basalt — How has the Whin 

 Sill been intruded among the strata, and what is its age — 

 And what is its relation to the perpendicular basaltic dykes ? 



* Trans. Nat. Hist. Soc. Northd., &c. 



