414 A Geognoslical Sketch of [Dec. 



There is another dyke, which occurs about ten miles west from 

 Newcastle, and prohably rises to some height above the surface of 

 the ground; for it is known by the name of Coaley Hill. 1 did 

 not myself see it j but I saw abundance of its contents as they are 

 driven to Newcastle, and used as stuff for mending the roads. The 

 substance was basalt, rather lighter coloured than usual. It con- 

 tained large crystals of felspar, and very minute black crystals, 

 which were probably augite. In some specimens there are round 

 cavities filled with chalcedony. I was not so lucky as to observe any 

 specimens of green-stone : though the existence of this basalt dyke 

 renders it very probable that dykes of green- stone likewise occur in 

 this coal-field. Various dykes occur between the river- Tyne and 

 ' Wear, and the heds in consequence are so much deranged that I 

 have a strong suspicion that some confusion exists with respect to 

 the identity of the different Tyne and Wear coal beds. 

 . 1 was led to expect from various accounts which 1 had received 

 that the coal in the neighbourhood of these dykes would be greatly 

 altered in its quality, and would be similar in appearance to coke ; 

 but I was not lucky enough to witness any such alteration, though 

 I examined the coal in the neighbourhood of various dykes, both at 

 Tvveedinouth and Newcastle, with considerable attention. Such 

 occurrences, therefore, must be rare, and like the disappearance of 

 the fiuor spar in the galena veins, I am afraid that in the present 

 state of our knowledge we cannot hope to be able to account for 

 them in a satisfactory manner. 



As the small coal cannot be sent to London, or sold to advantage 

 on the spot, great quantities of it are often piled up near the mouths 

 of the coal-pits. These masses of coal frequently take fire of them- 

 selves, and burn for a good many years with gieat brilliancy. Two 

 such heaps in combustion may be seen at present on the north side 

 of Newcastle. If yqu travel from Berwick to Newcastle, and enter 

 this last town in the dark, about three miles from the town, you see 

 two immense fires ; one on the left hand, about three miles from 

 the road, which has been burning these eight years. The heap of 

 coal is said to cover 12 acres. The other, on the right hand, is 

 nearer the road, and therefore appears more bright ; it has been 

 burning these three cr four years. These fires are not visible during 

 the day, but only during the night. It has often occurred to me 

 that this small coal might be converted into coke with profit, and 

 certainly in all cases where coal gas is wanted it would answer, as 

 well as any coal whatever. 



III. The third and last formation of these counties is the Mag- 

 nesian Lime-stone Formation. Though I now regard it as of 

 considerable importance, I must acknowlege with regret that my 

 examination of it was very superficial and imperfect. When I went 

 to Sunderland I was not aware of the nature of the country, and I 

 was so unwell that I found myself unable to travel over the country 

 sufficiently to determine the requisite points. My account, there- 

 fore, will not only be very imperfect, but unsatisfactory, as far as 

 the limits of this formation goes. I traced it from the river Tyne 



