KORTHUMBKRLAND AND DURHAM. 31 



east, and is traceable a distance of 7 miles, passing, in its course, 

 also through Mountain Limestone strata. On the Tweed it is 

 10 feet wide, but it thickens eastwards, and at Melkington it is 

 15 feet, and at Mattalees 33 feet wide. 



The Lindisfarne Dike has a course from eastward to westward, 

 but not straight. It crosses the south part of Holy Island in the 

 direction of south 85° east, and is seen two miles seaward, form- 

 ing the Plough and Goldstone rocks, on which the Pegasus was 

 wrecked. On the west side of the island the dike is exposed in 

 a high cliff, and is there 120 feet wide, with a slope to the south 

 of 95° ; large blocks of limestone are enveloped in the basalt and 

 highly metamorphosed, and the strata have a considerable upcast 

 on the south side. A calcareous shale, highly fossiliferous, lying 

 above a limestone, is remarkably metamorphosed — and near to 

 the Castle veins of the basalt penetrate the shale. This dike is 

 seen near T'enham, and afterwards a little northward of Kyloe 

 chm-ch, where it has a direction of S. 80° W., and is from 20 to 

 60 feet wide, increasing in width as it descends ; and in one part 

 it is covered by sandstones and shales. It cuts through the 

 Lowick coal field and is traceable westward to Leitham, the 

 whole ascertained course being about 1 4 miles. 



The Beadnell Bike is well exposed on the coast, rising like a Cy- 

 clopean wall through sandstone, limestone, shale, and coal beds, 

 whose relative position is but slightly altered, but whose struc- 

 tural characters are greatly changed : coal for some distance from 

 it is valueless, limestone near it will not burn into lime, and 

 shale and sandstone are indurated. The mutual transference of 

 qualities, between the basalt and the stratified rocks penetrated, 

 is well illustrated in this dike. Its width is generally 25 feet ; 

 the direction is south 85° west ; and it is traceable four miles in- 

 land as far as the Newham Station. 



The Howieh Bike is only 4 feet wide, sloping south 95°, and 

 with a direction of north 80° east. It is seen only on the coast, 

 and is remarkable for its wall-like appearance and its nearness to 

 the "Whin Sill, which, however, it is not seen to join. 



