HOLL MALVEEN HILLS. 73 



In that communication I also intimated that I should enter into 

 further details at no distant date ; but the completion of the paper 

 has been delayed by circumstances which were unavoidable. In 

 the meantime, I have been enabled to clear up certain points on 

 which I was not then altogether satisfied, and to avail myself of 

 some recent researches of my friend the Eev. J. H. Timins, of West 

 Mailing, into the chemical constitution of many of these rocks, which 

 have a bearing upon the subject of this memoir, as will be seen in 

 the sequel *. 



The objects of this communication are the following : — (1) to . 

 discuss the structure and origin of the crystalline rocks of the Mal- 

 vern Hills ; (2) to give the result of an examination of the super- 

 imposed Palaeozoic strata immediately adjacent; and (3) to endeavour 

 to show the chronological relationship of the several events in their 

 geological history. 



II. Metamoephic Eoces. 



It will be preferable to commence the description at the southern 

 extremity of the hills, where older deposits are seen resting upon 

 the metamorphic rocks than in the northern part of the chain, 



1. Keys-end Hill. — Some quarries at the southern extremity of 

 this hill, near Bromesberrow Park, exhibit thinly bedded gneissic 

 rocks dipping east. In one of these quarries the gneiss is mica- 

 ceous ; in the other two it is chiefly hornblendic, with some inter- 

 stratified thinner beds of dark micaceous gneiss, and a few bands 

 of hornblende-schist. Nearer to the central parts of the hill there 

 is some dark-coloured hornblende- and felspar-rock traversed 

 by a few small quartzo-felspathic veins, and beyond this, forming- 

 its northern half, are rocks which consist principally of imperfectly 

 formed hornblendic gneiss, with much greyish and greenish amor- 

 phous or semicrystalline rock, very much divided by joints, but 

 breaking with a smooth slaty fracture in the plane of the bedding. 

 Sometimes this rock is nearly homogeneous in appearance, or has a 

 minutely foliated structure ; at other times it has rounded grains of 

 felspar, and more rarely of quartz, scattered more or less abun- 

 dantly through its substance, frequently in a somewhat linear ar- 

 rangement. The bedding is best seen in the quarries at the southern 

 extremity of the hill, near the park, the strike being west of north 

 and south of east, and the dip easterly. In the other quarries it is 

 almost entirely obscured by the numerous joints and cross-joints 

 which intersect the rocks, and cause them to break readily into 

 more or less rhomboidal fragments, so that fresh surfaces are difficult 

 to obtain. These jointage-planes are much coated by peroxide of 

 iron, and exhibit abundance of slickensides. Small quartzo-felspathic 

 veins traverse the rocks in dififercnt parts of the hill, and a fault, 

 indicated by a narrow band of brecciated rock, is seen in one of the 

 quarries at its southern extremity. 



* Mr. Timins has now made more than two hundred analyses of (he Malvern 

 rocks, and his results will, I trust, be made known at no distant date. 



