510 Notices of Memoirs— W. W. Watts— J. F. Blake. 



Abstracts of Papers read before the British Association at 

 Oxford, August 9-14, 1894:. 



I. — On a Keuper Sandstone cemented by Barium Sulphate from 

 THE Pbakstones Eock, Alton, Staffordshire. By W. W. 

 Watts, M.A., F.G.S. 



PROFESSOE F. CLOWES ' has described a sandstone from the 

 Himlack Stone, near Nottingham, in which the grains were 

 cemented with crystalline barytes, the amount of this material 

 varying from 28 to 50 per cent, in diffei'ent specimens. This rock 

 occurred at the base of the Keuper sandstone of that locality. A 

 somewhat similar rock, occurring at about the same horizon, is 

 described by Mr. A. Strahan,^ from Beeston Castle in Cheshire, and 

 the same author refers to the frequent occurrence of barytes in the 

 Keuper breccias. 



Bearing these facts in mind, the writer visited a curious isolated 

 stack of rock, called the " Peakstones Eock," near the village of 

 Alton in Staffordshire, which is figured in Professor Hull's Memoir 

 on " The Triassic and Permian Eocks of the Midland Counties of 

 England." This stack is made of the Lower beds of Keuper sand- 

 stone, but its outer portion has lost whatever cement it may once 

 have contained. It is, however, situated at the end of a spur which 

 projects into a valley, and exposes a good deal of bare rock. This 

 rock contains what at first look like several veins of barytes two 

 or three inches thick, striking along the spur and straight through 

 the place occupied by the Peakstones Eock. On examination of 

 specimens the veins are seen to be planes in the sandstone cemented 

 by barytes. The specific gravity of the rock is 3'09, and, as the 

 grains are chiefly subangular fragments of quartz and felspar, it 

 must contain about 28 per cent, of barytes. This almost insoluble 

 cement has undoubtedly given rise to the spur above alluded to, and 

 almost as certainly has caused the survival of the Peakstones Eock. 

 This is, however, so much exposed to the weather on all sides, and 

 both to mechanical and chemical disintegration, that if any cement 

 is still left it must be in the inner part of the mass, which cannot be 

 reached by ordinary means. Another specimen from west of Kent 

 Green, near Congleton, containing barytes, and with a structure very 

 like that described by Mr. Strahan, was also referred to. 



II. — Sporadic Glaciation in the Harlech Mountains. By the 

 Eev. J. F. Blake, M.A., F.G.S. 



THE author drew a distinction between two results of glaciation — 

 the one, negative, in which the rocks are rounded and striated, 

 and all or nearly all the debris removed ; the other, positive, in. 

 which the rocks are covered by a thick deposit of drift with 



1 Eep. Brit. Assoc. 1885, p. 1038 ; 1889, p. 594 ; 1893, p. 732 ; and Proc. Eoy. 

 Soc. vol. xlvi. pp. 363-369. 



2 Mem. Geol. Survey. Exp. Quarter Sheet, 80, S.W. p. 7. 



