868 DR B. N. PEACH AND DR J. HORNE ON 



An important economic question arises as to the probability of finding workable 

 coal-seams in the Carboniferous area north of the Triassic rocks between Canonbie and 

 the river Nith below Dumfries. In the previous section (p. 866) evidence has been 

 given to prove that in the tract extending from the river Sark by Kirtlebridge, west- 

 wards to Clarencefield, near the mouth of the Nith, the three divisions of the Coal- 

 measures at Canonbie were removed by denudation before the Triassic rocks were 

 deposited. There is therefore no prospect of finding any part of the Coal-measures 

 within that area north of the Trias. The same evidence renders it very improbable 

 that the Coal-measures will be found underneath the Trias extending from the Cadgill 

 Burn near Kirkpatrick south-westwards to Annan, or below the basin of New Red Sand- 

 stone at Dumfries. 



Bores have been put down near Springkell, east of Kirtlebridge, which have proved 

 the existence there of thin coal-seams, but none workable. This result is what might 

 be expected from a consideration of the evidence in the field, for these thin seams lie 

 there below the Marine limestones of Kirtlebridge (d V11 , Plate III.), on the horizon of the 

 Lawston Linn coals of Liddisdale and the Scremerston coals of Northumberland (d vi , 

 PI. III.). These coals, as developed in Dumfriesshire, are of little or no economic 

 importance. It is probable, however, that representatives of the Kilnholm coals (d vui , 

 PI. III.) might be found underneath the Trias between Cadgill Burn and Annan, bub 

 even these seams, as they appear in Liddisdale, are too thin to be worked at the present 

 time. 



V. Comparison of the Carboniferous Subdivisions in Eskdale and Liddisdale 



WITH THOSE IN NORTHUMBERLAND AND CENTRAL SCOTLAND. 



The evidence relating to the correlation of the Carboniferous subdivisions in Eskdale 

 and Liddisdale with those in Northumberland is fortunately of a conclusive character. 

 To Mr Tate, of Alnwick, belongs the merit of having been the first to establish the 

 sequence of the Carboniferous rocks in north Northumberland, where he worked it out 

 between 1849 and 1868. His classification is given below : — 



3. Calcareous group, embracing all the beds from the base of the Millstone 

 Grit down to the Dun Limestone, and containing numerous marine lime- 

 stones, with alternations of sandstones, shales, and coal-seams. 

 2. Carbonaceous group, with various workable coal-seams (Scremerston coals) 



and thin limestones, usually impure. 

 1. Tuedian group, comprising all the strata between the base of the Carbon- 

 aceous division and the Upper Old Red Sandstone, and containing shales, 

 clays, sandstones, and thin beds of argillaceous limestone (Cementstone 

 group). 

 This classification has been adopted by the Geological Survey with one modifica- 

 tion, viz., the insertion of the Fell Sandstone group between the Tuedian and 

 Carbonaceous divisions. The detailed mapping of the border territory has shown 



