320 Mr. N. Wood on the Geology of Northumberland, ^c. 



Midgeholme and Tindal Fell the Coal-beds are found cut off by a mass 

 of Whin. This is probably occasioned by a Whin Dyke intersecting the 

 line of the Slip Dykes, and then following their direction ; as we find a 

 Whin Dyke, which occurs near St. Oswald's Church above Chollerford, 

 stretches across the South Tyne near the chain bridge, and passing 

 Wharraley, proceeds in a direction towards Whitfield, where a Basaltic 

 Dyke is seen crossing the West Allen. Diverging a little from this 

 course, a Basaltic Dyke crosses the South Tyne near Harper Tower, 

 following the line of the Slip Dykes, 



The Midgeholme Coal Basin is the western extremity of this narrow 

 slip of Coal Measures. Proceeding westward along the line of the 

 Dykes, we find the strata on the north side rising rapidly from the Coal- 

 field of Midgeholme, or from the boundary of the two counties ; and in 

 a very short distance on the east side of Tindal Fell, we pass the Grit 

 Rocks rising out from underneath the Coal Measures, and meet with the 

 first Limestones on Tindal Fell. 



The line of Dykes here diverges considerably to the south-west, and 

 the strata become more flat, and take a gradual rise west, or rather 

 towards the south-west ; stretching away towards the escarpment rising 

 above the plain of Red Sandstone, where we find the beds of Lime- 

 stone bassetting out. 



As above stated, at Tindal Fell we find the upper Limestones, rising 

 from below the Coal Measures. Accompanying these, we find a work- 

 able bed of Coal, which forms the Coal works of Lord Carlisle, on the 

 north brow of that fell. The Coal here consists of one workable bed, 

 about four feet thick, lying underneath a bed of Limestone, from which 

 it is separated by about forty feet of Sandstone and Shale. From the 

 alteration of the dip of the strata, this Coal-bed, besides stretching away 

 north-eastward, as will be noticed hereafter, widens out westward ; and 

 is again, after passing a series of Slip Dykes on the west side of Tindal 

 Fell, found at Talkin. 



At this place the determined direction of the strata is north and south 

 nearly, rise west about 1 in 11 or 12. This bed of Coal consequently 



