Vol. 54.] EAILWAY BETWEEN LINCOLlsr AND CHESTERFIELD. 



165 



in fig. 4; but, owing to the present state of the catting, it is 

 difficult to make out what really occurs. 



Fig. 4. — Section at the luestern end of Duokmanton Tunnel^ showing 

 the curious break -up of the coal-seam on the northern side. 



a = Shales, sandy shales, and sandstones. 



6= Coal, about 6 feet thick at the tunnel : this thins out westward, and breaks 



up into patches. *" 



c =01ay and shale. 

 ^= Sandstone, thinning out westward, 



[On the south side of the cutting the coal is represented by one small patch.] 



Close to the top of the tunnel-arch there is a fault, as shown in 

 the figure, but there is no trace of it beneath the large coal-seam. 

 The fault on reaching the coal-seam appears to have developed into 

 a lateral thrust, which has drawn out the coal in a long tongue to 

 the west, and broken it up into a series of isolated patches that 

 extend for 50 yards or more. These patches being high up in the 

 nearly vertical cutting, it is not easy to examine them carefully, and 

 one does not feel sure as to the true interpretation of this very 

 curious section. As this cutting is near the foot of a rather steep 

 escarpment, it is possible that no true fault exists, but that we have 

 here the section of a verj^ considerable landslip. 



"Within 1200 yards of the tunnel-mouth the line crosses no less 

 than six faults, showing the broken nature of the strata hereabouts. 

 The rocks consist of alternations of sandstones, shales, and thin 

 coals, with thick shale in the upper part and massive sandstone at 

 the bottom. The dip decreases gradually from 15° at the tunnel 

 till the great anticlinal axis, which traverses this part of the coal- 

 field, is reached. This axis is crossed at 800 yards from the tunnel, 

 and forms a fairly flat arch in the thick beds of sandstone and shales, 

 which is beautifully shown in the deep cutting that occurs at this 

 point. 



Beyond this the inclination of the beds turns over to the west, and 

 the dip gradually increases, to as much as 25° at Hady Lane, where the 

 outcrop of the Black Shale Coal with the Ironstone series above it 



a. J. Gc. S. No. 214. N 



