162 Future Extension of the English Coal-fields. 



Wales, and still more to the north, skirting the Cumbrian or 

 Lake Mountain .r-oup. Lastly, I shall speak as to the coal- 

 fields of our south-western districts of Somerset, Gloucester 

 and South Wales. 



I. The Northumberland and Durham coal-field is well 

 known, extending from the mouth of the Coquet on the north 

 to the banks of the Tees on the south. The dip of the strata 

 is along the northern edge to the south-east, and through the 

 middle of the field due east; but at its southern extremity 

 along the Tees, near Bishop's Auckland, the line of bearing 

 appears to curve, and they change their dip, first to north and 

 then to north-west. Along the south-eastern border they are 

 uniformly overlaid by a terrace of magnesian limestone ; but 

 Mr. Sedgwick has satisfactorily shown that they are capable 

 of being profitably pursued beneath this limestone, and ac- 

 tually have been so in many instances. Here, therefore, is an 

 extension of the field apparently limited only by the expense 

 of deep drainage. But the most important point connected 

 with our inquiry presents itself on the south of the Tees, 

 where, in consequence of the curvature which we have men- 

 tioned of the line of bearing of the coal strata to the east and 

 north-east, the magnesian limestone, extending in its regular 

 course to the south, overlies unconformable their edges, and 

 comes in contact with the more unproductive subjacent strata 

 of millstone grit, &c. Now it ought carefully to be ascer- 

 tained whether this curvature near Bishop's Auckland be 

 more than a merely partial inflection ; and whether the main 

 coal strata do not speedily resume their southerly bearing, 

 beneath the covering of the magnesian limestone, under such 

 circumstances that they might still be profitably worked. 



From the Tees to the Wharfe the eastern terrace of mag- 

 nesian limestone in its course through northern Yorkshire 

 appears almost immediately in contact with the more barren 

 inferior strata; but Mr. Smith, in his Geological Map of 

 Yorkshire, has indicated a thin zone of carboniferous measures 

 as accompanying the greater part of its course; and Mr. 

 Sedgwick has indicated coal as worked in this interval near 

 the banks of the Gore at Winksley, and on the right bank 

 of the Nid near Bilton. Now if in pursuing these indica- 

 tions eastward in the direction of the dip beneath the mag- 

 nesian limestone the main seams were recovered, and traced 

 throughout the interval between the Tees and Wharfe, a di- 

 strict fully equal to those already worked might be laid open ; 

 and as the seams of the Somersetshire coal-field are worked 

 under a still thicker covering of superincumbent strata of 

 magnesian limestone, red marl, and lias, I do not doubt that 

 these might be worked with equal ease; and I believe I have 



