internal Structure of the Magnesian Limestone. 59 



deserted) have been sunk through the plateau of limestone on the west side of the Roman road. 

 Near Church Garforth the dip of the coal-measures is nearly due south ; and, consequently, to 

 the north of the village the successive beds rise towards the surface, and probably are only pre- 

 vented from abutting against the superincumbent limestone by some beds of yellow sand and red. 

 coloured clay, which are there interposed between the two formations. It was undoubtedly in 

 consequence of this peculiarity of position that the ancient works commenced within the region 

 of the limestone. Had the limestone been conformable to the coal strata, the several seams 

 would have been most easily accessible on the west side of its escarpment ; and the first exca- 

 vations would have commenced in that quarter*. 



7. North of the Wharfe the magnesian limestone ranges over the lower and almost unproductive 

 part of the coal formation. On the right bank of the Nid several works have, however been 

 carried down to an impure bed of coal about three feet thick. The pits are seen a little to the 

 north-west of the Bilton outlier ; but none of them were sunk through it. There are also the 

 remains of some ancient works at Winksley, a little to the west of the limestone. From the 

 neighbourhood of Bedale the formation (as far as we can judge from the few remnants of it which 

 are visible) appears to have ranged into the county of Durham, upon a portion of the carbonife. 

 rous series which is generally classed with the millstone grit. 



8. On the north side of the Tees the magnesian limestone, as appears by what is above stated, 

 occupies for several miles a nearly level region, which terminates at the base of the carboniferous 

 hills near Houghton-le-Side. The position precisely resembles that of the conglomerates, which 

 are spread over the outskirts of the carboniferous limestone in the south-western coal districts of 

 England, and is accounted for in the same way by the want of conformity between the magnesian 

 limestone and the beds of the coal formation. 



This fact is still more unequivocally shown in the range of the formation from Houghton-Ie- 

 Side to Ferry Hill. The south-western extremity of the Durham coal-field is deposited in the 

 form of an irregular trough or basin. The beds on one edge of this trough rise upon the lead, 

 measures, and dip to the S.E. ; but on the south-eastern edge they rise towards the terrace of 

 magnesian limestone, and dip on the whole towards the N.W. Over this south-eastern-edge 

 ranges the limestone (in the manner pointed out above) ; and in its whole course, from Houghton- 

 le-Side to Ferry Hill, dips towards the S.E. It is impossible to conceive a more complete instance 

 of want of conformity between two formations. 



The facts on which this conclusion rests are indicated in all the quarries of the district, and in 

 the sections formed by various coal- works which have been opened in the line of the limestone. 

 At the Brussleton coal-works the average dip is about N. by E. In the Shildon works (some of 

 which were formerly sunk through the limestone) the dip was about N. by W. At the village 

 of Eldon the dip is nearly the same. Many old works were sunk through the limestone ; and as 

 these were exhausted, it became necessary to sink further upon the dip. The present works are 

 on the west side of the limestone escarpment. At Goundou the coal-measures rise towards 

 the limestone, and probably pass under it; but the present works are at some distance ou 

 the west side of the terrace. The dip of all the neighbouring coal strata is about N.N.W. 

 Lastly, at Ferry Hill both the ancient and modern works are sunk through the plateau of mag- 

 nesian limestone, which has a slight inclination to the S.E. After passing through about eight 



* The present pits near Church Garforth are to the west of the limestone escarpment. This 

 part of the field has been proved to contain twelve beds of coal ; four only of which are worked. 

 In one pit these four beds are found at the respective depths of 38, 58, 91, and 181 yards. Tiie 

 two lower beds (called the high and lozo main) are each about five feet thick. 



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