Vol. 6^.~] THE TOADSTOXES OP DERBrSHIRE. 247 



of the dale led me to explain the relative positions of the rocks by 

 two faults within a short distance from one another, running in a 

 direction from north-west to south-east, which have let down the 

 toadstone lying between them. Several calcite-veins, one of them 

 2 or 3 yards wide, traverse the toadstone in a direction parallel to 

 the faults. The limestones immediately to the north of the northern 

 fault are very much disturbed, and in one place are vertical. 



These faults have produced a marked change of feature in the 

 landscape. Walking up Great Eocks Dale, when we arrive at the 

 southern fault at the northern end of the short railway-tunnel, 

 we see that the narrow, flat-bottomed, rocky valley, with its almost 

 perpendicular cliffs of limestone on each side, suddenly loses its 

 gorge-like aspect, and becomes for a short distance a broader grass- 

 covered dale. The limestones south of the fault near the tunnel- 

 mouth form an almost perpendicular cliff parallel to the fault. 



The lower lava is also found at Blackwell (on the road from 

 Miller's Dale to Taddington), west of Calton Hill, and in the village 

 of "Wormhill. 



The lava in the faulted inlier of Tideswell Dale, which has been 

 invaded by the sill (so that in some places it is below, and in others 

 above, the intrusive dolerite), lies some distance below the upper 

 lava on Hamerton Hill, and is probably part of the lower lava of 

 the area. 



Uncorrelated Lava-Flows. 



In addition to the two main lava-flows there are several isolated 

 patches of lava, the horizon of which I have not been able to 

 determine. Pour of them occur a short 'distance to the south of 

 Buxton, namely in Ash wood Dale and on the road to Ashbourne, 

 on Staden Low, on Fox Low, and on Staker Hill. Although I am 

 not quite sure, I think that they belong to the lower lava of the 

 district. 



In Tideswell Dale, south of the southern fault are two thin 

 lava-flows, which are nearly on the same horizon as the lower lava 

 of the district. North of the northern fault is an outcrop of lava 

 which may be on the same horizon as one of those to the south of 

 the southern fault. Opposite the Tideswell gas-works a lava was 

 seen faulted against the limestone on the north until a few years 

 ago. Since then a wall has been built which conceals the fault, 

 but the vesicular toadstone may be seen south of the wall. 



On the western face of Fin Cop, between Ashford and Taddington, 

 are two lavas each about 30 feet thick and separated by about 

 150 feet of limestone. In the absence of any evidence to the 

 contrary, they might be considered as the thinning-out of the two 

 main lavas of the Miller's-Dale area. The lithological character of 

 the limestones above the upper lavas militates, however, against 

 this conclusion. The upper lava of Fin Cop is overlain by at least 

 250 feet of thin limestones with chert, but the upper lava of Miller's 

 Dale is succeeded by about 120 feet of massive limestones without 



