Yol. 6^.~] THE TOADSTONES OF DERBYSHIRE. 257 



the west to Matlock on the east, a distance of about 5| miles. 

 The igneous rocks are seen at the surface, through an area not 

 greater than 56 square miles. There are two main lava-flows 

 (one of them accompanied by tuff), several vents, intrusive sills, and 

 tuff unaccompanied by lava. 



The Upper Lava. 



The upper lava-flow appears in the railway-cutting near the 

 mouth of the tunnel north of Matlock-Bath Station. It may be 

 traced under the escarpment of the High Tor in a northerly 

 direction, on the eastern side of the Derwent for nearly a mile; it is 

 then carried down and across the river by the dip of the beds, and 

 can be followed on the opposite side of the dale by Masson Farm 

 in a north-westerly direction to near Oxclose Mine. It apparently 

 thins out here, and I have been unable to find it farther west. 

 From Matlock-Bath railway-cutting it may be followed across the 

 river in an easterly direction, and is carried up by the rapid dip 

 of 40° to the Heights of Abraham by the Yictoria Tower. The 

 Tower is built on limestone-beds above the toadstone, which dip 

 steeply soirth-eastward under the Yoredale Shales at Matlock-Bath 

 Station. The outcrop descends through the grounds of the Heights 

 of Abraham, and crosses the river near the Jubilee Footbridge. 

 It may be followed in a southerly direction below the escarpment 

 of limestone past the Lover's Leap to Masson Mills on the eastern 

 side of the dale. From this point I have been unable to follow it 

 farther. As the beds dip south-eastward, it should cross the river 

 near the Mills. "W. Hopkins : states that the toadstone is found on 

 the eastern bank of the river, and again in the foundation of a 

 house not far below the Cotton Mill. It may be cut off by a fault, 

 which would almost coincide with a mineral-lode on the 1-inch 

 Geological-Survey map. I have, therefore, only marked it on the 

 map so far as I have been able to trace it. 



The surface of the upper lava was seen by me at the bottom of 

 Cawdor Quarry, north of Matlock-Bridge Station, a few years ago. 



In Bradford Dale (see map, PI. XX) a bed of vesicular lava is 

 exposed, which I am inclined to refer to the upper lava of the 

 Matlock District. A rough section gives about 150 feet of 

 limestones between the shale and the underlying lava. The upper 

 50 or 60 feet of the limestones consist of thin beds with chert, and 

 the lower portion of massive limestones. This is very similar to 

 the section at Matlock Bath. 



The Lower Lava. 



The lower lava is much more extensive than the upper, and is 

 separated from it by from 80 to 100 feet of limestone. In Matlock 



1 ' On the Stratification of the Limestone District of Derbyshire ' [privately 

 printed] 1834, p. 39. 



Q.J. G.S. No. 251. t 



