170 iTR. H. H. AEXOLD-BEMEOSE ON A QrAETZ-EOCK [May 189S, 



quartz-rock is neither distributed universally throughout the lime- 

 stone series nor restricted to certain beds in it. There is, on the 

 other hand, sufficient evidence to show that it occurs irregularly in 

 the limestone, and is found most plentifully in two small areas : the 

 southern, near Bonsall, and the northern, near Castleton. In the 

 southern area it occurs in the limestone-beds below the second 

 Toadstone of Masson, and therefore 400 feet at least below the top 

 of the limestone, while in the northern area it occurs in the cherty 

 beds near the top of the series. 



The presence of the quartz-rock in the northern area was men-- 

 tioned in the Geological Survey Memoir of Xorth Derbyshire, and 

 some of -its aspects in the field were briefly described, but no 

 systematic attempt appears to have been made to ascertain its origin, 

 and there is no mention made of its microscopic structure. The 

 quartz-rock in the southern area does not appear to have been 

 described. It will be dealt with first in this paper, because I had 

 finished working at it before I examined the northern district. 



II. The Sotjthekn Aeea. 



This small area, immediately east of the village of Bonsall 

 (6-inch map 34, I^.W.), is situated between Bonsall on the 

 west, Ember Farm on the east. Pounder Lane on the north, and 

 Ember Lane on the south. The quartz-rock occurs plentifully in 

 the walls in isolated and irregularly-shaped bosses, and in large 

 blocks on the surface of the ground. Sometimes this rock, in 

 common with the ordinary and dolomitized limestone of the sur- 

 rounding district, is traversed by veins of fluor. The quartzite, 

 quartzose limestone, and the ordinary limestone were mapped by me 

 on the scale of 25 inches to a mile. The limestone dips generally to 

 the eastj at an angle of from 15° to 20°, below the lava which forms 

 the summit of Masson Hill. On the south is the agglomerate of 

 Ember Lane, and on the east the large mass of ophitic olivine- 

 dolerite, which at present I consider to be either a sill or the 

 remains of a volcanic neck, since it cuts across the limestone-beds. 



An examination of the map shows that the quartzite and quartzose 

 limestone are not confined to one horizon, but occur as bosses in the 

 limestone at various horizons. The following outcrops will be 

 described : — 



(a) The 'Top Lift; 



(b) The ' Old Chert-quarry.' 



(c) 100 feet north of (b) and in the same field. 



{d) Field north of, and adjoining the preceding field, 

 (e) Field east of, and adjoining Founder Lane. 

 (/) Moorlands Lane. 



(a) The ^ Top Lift.' 



The footpath from Ember Lane to Pounder Lane passes on the 

 left a bold, irregularly-shaped mass of rock (the ' Top Lift '), 

 which is totally unlike the limestone of the district. A number 



