536 C. CALLAWAY ON A SECOND PEECAMBRIAN 



37. On a Second Precambkian Geotjp in the Malvern Hills. By C. 

 Callaway, Esq., D.Sc, M.A., E.G.S. (Read May 26, 1880.) 



The Herefordshire Beacon, situated a little south of the middle of 

 the Malvern range, sends out towards the east and south-east 

 several buttresses or spurs ; they occupy an area of about one mile 

 from north to south and half a mile from east to west. In the 

 summer of 1878 I visited the Malvern Hills to compare the rocks 

 with those of Shropshire, and I was sanguine, from Dr. Holl's de- 

 scription of this district, that I should find in it some equivalents of 

 the younger Precambrian group of that county. In his valuable 

 and thoroughly scientific memoir on the Malvern Hills, published in 

 the Journal of this Society in 1865, Dr. Holl describes the area in 

 question as " occupied by baked rocks * of the probable age of the 

 HoUybush Sandstone and Black Shales," the alteration of the rocks 

 being supposed to be due to immense trap-dykes — a very natural 

 interpretation of the facts when we consider the vague ideas of petro- 

 logy and of metamorphism which prevailed 15 years ago. On my first 

 visit I had the advantage of Dr. HoU's guidance. I found that he 

 had advanced beyond his original position, and was quite prepared to 

 consider a new reading of the district. I saw at a glance that the 

 rocks were quite of a type with which I had been familiar in Lilles- 

 hall Hill, the extreme north-easterly summit of the Salop Precam- 

 brian chain. The prevailing variety is a very compact, flinty, horn- 

 stone t (note 1, p. 538) of a grey or reddish-grey colour, undistin- 

 guishable from the rock forming the craggy boss which crowns the 

 summit of Lilleshall Hill (note 3). I have seen this rock in almost 

 every part of the Malvern mass, from near its junction with the 

 gneissic axis to where the spurs break down abruptly upon the Tri- 

 assic plain to the east. At the south-east end, overlooking Castle 

 Morton Common, is a greyish felspathic breccia. The contained 

 fragments are similar to the hornstone. Here and there the rock is 

 less compact, and closely resembles some of the indurated ash of 

 Lilleshall Hill. Dr. Holl refers to " an unaltered sandstone " and to 

 some " black and green shale," both near Little Malvern ; but I have 

 been unable to detect these rocks, and they are obviously quite 

 subordinate to the hornstones. I could not satisfy myself as to the 

 strike of the beds ; but I noticed the "^ softer and less siliceous" band 

 which intervenes between the hornstone and the ridge, so that it 

 would appear as if the strike were parallel to the gneissic axis, and 

 therefore quite discordant to the strikes of the older series. 



That the newer Precambrian rocks of Malvern are to be correlated 

 with the younger of the two Salopian groups, or with a part of it, 

 receives support from the similarity, I might almost say identity, of 



* Dr. Holl gives a section showing the position of the " baked rocks," 

 at p. 92. 



t I use the term "hornstone " with hesitation. It seems to me that a new 

 term is wanted for these rocks. They hardly correspond to Halleflinta. 



