CLEVELAND BASALT DYKE. 



135 



charred the coal on each side of it, and rendered it soft and sooty ; 

 to use the language of a quarry man, who was working in the dyke 

 when I visited the place in 1813, " it had burned the coal wherever 

 it had touched it." The same dyke extends from the sea to the 

 western side of the county of Northumberland ; its termination in 

 that direction is unknown. 



The longest mineral dyke that has been traced in England maybe 

 called the Cleveland Basalt Dyke : it extends from the western side 

 of Durham to Barwick in Yorkshire ; it crosses the river Tees, at 

 this place, and proceeds in a waving line through the Cleveland Hills 

 in the east riding of Yorkshire, to the sea between Scarborough and 

 Whitby. It rises to the surface, and is quarried, in many parts of its 

 course, for stone to lay upon the roads. From Barwick-on-the-Tees 

 it may be traced in an easterly direction, near the villages of Stanton, 

 Newby, Nunthorp and Ayton. At Langbath-ridge a quarry is work- 

 ed in it ; it passes south of the remarkable hill called fioseberry 

 Toppin, near Stokesly, and from thence by Lansdale to Kildale ; 

 it may be seen on the surface nearly all the way in the above track. 

 From Kildale it passes to Denbigh Dale end, and through the village 

 of Egton-bridge, and hence over Leace ridge through Gothland, 

 crossing the turnpike road from Whitby to Pickering near the seven 

 mile stone, at a place called Sillow Cross on a high moor. I exam- 

 ined it at this place, where it is quarried for the roads, and is about 

 ten yards wide. From hence it may be traced to Blea Hill near 

 Harwood Dale, in a line towards the sea, near which it is covered 

 with alluvial soil ; but there can be little doubt that it extends into the 

 German Ocean. It is a dark greyish brown basalt which turns brown 

 on exposure to the atmosphere ; it is the principal material for mend- 

 ing the roads in the district called Cleveland. I am indebted to Mr. 

 Bird of Whitby for an account of the situations where it may be seen 

 on the surface. He has traced it through Yorkshire and Durham ; 

 in the latter county it cuts through the coal strata. Professor Sedg- 

 wick, in a valuable paper on the Trap Dykes of Yorkshire and Dur- 

 ham, published since this account of the Cleveland Basalt Dyke was 

 originally written, says that the continuity of this dyke with others 

 west of the Tees, is not fully ascertained : he thinks the length of 

 the dyke may be estimated at from fifty to sixty miles. The course 

 of this dyke is marked in the Geological Map of England, Plate IV. 

 By consulting the large maps of England, the course may be distinct- 

 ly traced; drawing a line in the direction from Cockfield in the coun- 

 ty of Durham to Barwick-on-the-Tees, and extending the line east 

 and west, it will pass near all the places above mentioned. In some 

 situations where the angle in which this dyke cuts the strata can be 

 ascertained, it is about eighty degrees. 



A circumstance attending this and other extensive dykes, which 

 has not, 1 believe, been hitherto regarded by geologists, completely 

 invalidates the theory, that dykes were originally open fissures form- 



