246 MR. B~. H. AEN0LD-BEME0SE ON [Aug. I907,. 



The Lower Lava. 



The lower lava of this district is seen at the bottom of the valley 

 of the Wye, a short distance east of Miller's-Dale Station, and can 

 be traced as far as Raven's Tor, where it disappears under the lime- 

 stone which dips south-eastward. The igneous rock is brought up 

 by a small dome in the limestone. It is much decomposed, and 

 good sections of the vesicular and amygdaloidal type are seen by 

 the roadside. 



The exposures of the toadstone in Monk's Dale and Chee Dale 

 belong to the lower lava-flow. In Chee Dale, near the river, 

 occurs a vesicular and amygdaloidal rock which can be traced across 

 the river, and up the hill on the opposite side to the top of the tunnel 

 in a westerly direction. It is carried up by the rapid dip of the 

 limestone-beds on the eastern side of the Dale, and can be followed 

 through Tunstead and Great Rocks Lees, by the village of Small- 

 dale, then by the north-east of Withered Low through Hargatewall 

 and into Monk's Dale. I have only been able to trace it for a short 

 distance on the eastern side of this Dale. After a break of about 

 half a mile in a northerly direction it is found again, and can be . 

 traced through Wheston and under the escarpment of Wall Cliff, 

 across Brook Bottom (a small valley north-west of Tideswell), thence 

 under the Cop as far as Starvehouse Mine near Oxlow Rake. A 

 small fault near Brock-Tor Dam shifts the outcrop a short distance 

 to the west, in a way similar to that in which another fault con- 

 nected with Moss Rake shifts the outcrop of the upper lava near 

 Piece Barn. I have been unable to trace it farther north, as mapped 

 by the officers of the Geological Survey, round the face of Oxlow to 

 Eldon Hill. If it extended in that direction, it should be observed 

 crossing Conies Dale between Oxlow and Eldon Hill. Through 

 the whole extent of this short dale the limestones are seen dipping 

 north-eastward at an angle of 5°, which increases to 15° at the top 

 of the dale ; but no outcrop of toadstone can be seen. The absence 

 of the lower lava near Eldon Hill is confirmed by the observa- 

 tions of Mr. S. Moore, of Castleton. He states that, between Eldon 

 Hill and Oxlow Dam, he could find no evidence of an outcrop of 

 toadstone. 1 



Returning to Tunstead, we find on the opposite (western) side of 

 the dry valley up which the Midland Railway runs to Peak-Forest 

 Station, a lava that is evidently on the same horizon as the lower 

 lava. It can be traced from Great Rocks Pastures to Higher 

 Bibbington, and within a short distance east of Dove Holes into 

 Holderness Quarry. The vesicular toadstone north and west of 

 the Waters wallows Sill probably forms part of the same bed. 



Near Upper Great Rocks the toadstone, which is vesicular and 

 amygdaloidal, almost abuts against the limestone, and is found within 

 a few feet of it. At first, I thought that it might be an intrusive 

 mass ; but a further examination of the ground on the western side 



1 Geol.Mag. 1903, p. 85. . . , ; 



