of the South IVesh Coal-basiti. 113 



die line between the outcrop of the highest and lowest bed of 

 this series. Now the dip along this line varies greatly, being, 

 in the north, from 1 in S-t to 1 in 12; and on the south, where 

 the beds are most disturbed, 2 or 4 in 10 : but as the dip of 

 about 1 in 12 predominates through much the most conside- 

 rable portion, I think we may take the average as 1 in 8, 

 which will give 100+ fathoms per mile, and this will yield a 

 breadth of 2 miles, measured from the outcrop to that point 

 where the beds reach the assumed extreme workable depth of 

 200 fathoms beneath the level of the valleys ; but since, after 

 thus first making their appearance on the surface, they range 

 at least a mile further along the sides of the hills, we may take 

 3 miles as the breadth of the workable zone ; its superficial 

 extent will be, therefore, 35x3 miles =105 square miles. 

 The anticlinal line of Cefn Eglwysillan must again bring these 

 beds within working depth, from Newbridge east to Bed- 

 was, near which this line inosculates with the outer edge of 

 the basin: but the strata along this line have not yet been 

 explored, not being raised anywhere quite to the surface ; 

 though just across Newbridge, in the next district, there are 

 pits on them. I will not, however, make any allowance on 

 this account, but take it as a set-off against the quantity 

 worked out on the north edge among our iron works. 



The middle series in this district I consider as nowhere 

 sinking beneath the working level, and the coal may therefore 

 be procured wherever the series exists. Drawing a line through 

 the middle of the outcrop of this series (to allow for the less 

 extent of its upper members), I make it occupy, in the part 

 of this district north of the Eglwysillan Saddle, an extent of 

 80 square miles, and south of ditto, about 30; total, 110 

 square miles. The upper coals form an oval between Llan- 

 vabon and Crumlin Bridge (I refer always to places in Mr. 

 Greenough's Map), about 8 miles long x 3 broad = 24 

 square miles ; this is in A, north of the Saddle. I do not know 

 that this series is found in B. 



District II. — The lower series is not, I believe, anywhere 

 below the working level in this district. I calculate its extent 

 north of the Saddle in A, 200 square miles; and south of it 

 in B, 100 square miles. The middle series is here also about 

 100 square miles in A, and 50 in B; the upper series hardly 

 takes ground anywhere in this district. 



District III. — The lower coals are workable all along the 

 northern outer edge ; but as the southern edge is much broken 

 into by Swansea Bay, &c. we cannot take the line at more than 

 40 miles long. 1 take the workable breadth of this zone at 

 3 miles, which gives for the result 120 square miles. The 



N. S. Vol. 1 1. No. 62. Fc'0. 1832. Q middle 



