192 



MESSRS. KIRKBY AND DUFF ON THE 



seams is shown to run about 

 east and west in the north part 

 of the coal-field, which of course 

 implies the dip to be to the 

 south. Moreover, it is well 

 known that immediately to the 

 north of the Yorkshire coal- 

 field, the Millstone Grit comes 

 to the surface and ranges over 

 a broad band of country on to 

 Knaresborough and Ripon, just 

 as the same rock comes up be- 

 neath and extends beyond the 

 coal-field in South Durham. 



It would thus appear that 

 the Yorkshire coal-field ends 

 on the north by its Measures 

 outcropping sharply to the north 

 and north-west ; while the Dur- 

 ham coal-field on the south 

 ends, so far as can be seen or 

 known, by the outcrop of its 

 Measures to the south, or by 

 their rising and abutting in that 

 direction against the Magnesian 

 Limestone, as at Thrislington 

 and other places. The follow- 

 ing figure will assist in ex- 

 plaining our views on this 

 point : — 



We of course hold with most 

 geologists that the coal-fields of 

 Durham and Yorkshire were 

 once united, forming, in fact, 

 with those of Cumberland, Lan- 

 cashire, and possibly others, 



■Yorkshire Coal-field. 



.Millstone Grit. 



-Yoredale Rocks with 

 outcropof Great Lime- 

 stone at Moulton, 

 Middleton Tyas. 

 Barton, &c. 



Millstone Grit. 



■ 



• Durham Coal-field. 



■m 



