254 ME. H. H. ARNOLD- BEMR0SE ON [Aug. 1907, 



Ravensdale Tuff. — Cressbrook Dale, which runs from 

 Wardlow Mires on the north to Cressbrook Mill on the south, 

 forms a gorge in the Mountain Limestone. At the southern end 

 of the dale is a bed of lava, which may be traced on both sides 

 for a short distance. "Walking up the bed of the stream, which is 

 often dry, we pass through a narrow gorge in the limestone 

 about 9 yards broad at the bottom, and about 16 yards across at 

 the top. We soon come to a perpendicular but natural wall of 

 limestone : the beds are nearly horizontal. A short distance to the 

 north we enter a wider valley, the bottom of which consists of a 

 bedded tuff evidently cut off from the limestone by a fault running 

 nearly due east and west. The limestone is seen within 2 yards 

 of the tuff. The base of the latter is not exposed, and so it is 

 impossible to estimate its thickness. A short distance north of 

 Kavensdale Cottages (locally known as ' Bury my Wick ') 20 feet 

 of tuff are seen in the bank of the stream. The tuff can be traced 

 for nearly half a mile up the valley, where it dips under the 

 limestone at an angle of about 25° in a north-easterly direction. 

 The tuff consists of red and brown lapilli, in a cement of lapilli 

 and volcanic detritus, and contains small pieces of limestone and 

 blocks of a hard and dark igneous rock. 1 



Litton Tuff. — This tuff was mapped on the 1-inch Geological- 

 Survey Map from Tideswell Lane, through the village of Litton, 

 across Cressbrook Dale to Peter's Stone, a distance of nearly 

 li miles. I have been able to trace it for a distance of over 

 2 miles. The best exposures are at the eastern end of Litton, at 

 Peep o' Day, and under Peter's Stone. The tuff runs on from under 

 Peter's Stone on the eastern slope of Cressbrook Dale, to a point 

 west of Wardlow Hay, where all vestige of it is lost. It may 

 also be followed in the opposite direction north-west of Litton 

 under Litton Edge, across Conjoint Lane ; and, instead of turning 

 northward to Tideswell-Lane Head (as mapped by the Geological 

 Survey), it strikes across the road from Tideswell to the Lane 

 Head, through the fields north-east of Tideswell to within a short 

 distance of the limestone-quarry on the Peak-Forest road, two- 

 thirds of a mile north-west of the Lane Head. 



The tuff is laminated, and consists of lapilli which are mostly 

 vesicular ; some of them contain pseudomorphs of olivine, lath- 

 shaped felspars, and magnetite. Rounded pieces of fossiliferous 

 limestone and blocks of dolerite occur in the tuff. 2 The limestone 

 which rests upon the tuff at Litton is granular, very fossiliferous, 

 and contains lapilli up to a height of more than 20 feet. A 

 small quarry at the back of the house called ' Peep o' Day ' yields 

 the following section : — 



1 Quart. Journ. Geol. Soc. vol. 1 (1894) p. 630. 



a Ibid. pp. 628-29 ; see also Sir Archibald Geikie, ' Ancient Volcanoes of 

 •Great Britain' vol. ii (1897) p. 21. 



