HOLl MALVERN HILLS. 93 



This area is about a mile in length, extending from the ravine 

 nearly opposite Little Malvern to the middle of Castle Morton Com- 

 mon, and has an extreme width, opposite the sonthern extremity of 

 the British camp, of three-eighths of a mile. It is invaded exten- 

 sively by trap-dykes, to which the altered condition of the rocks is 

 due. The central portion of the area, on the slopes of the hills 

 forming the eastern buttresses of the Beacon, is occupied chiefly by 

 highly siliceous rocks of a greyish and pale reddish-grey colour, 

 which pass, where most distant from any trap-dyke, into semi- 

 vitrified sandstone, mostly of light colours, and which becomes con- 

 glomeratic in the south- easternmost hill overlooking Castle Morton 

 Common. For the most part, however, it is a hard, compact, often 

 flinty rock, which in the vicinity of the trap-dykes frequently 

 takes on an imperfectly porphyritic structure, small crystals of 

 glassy felspar and a few scattered points of quartz appearing 

 in the mass ; and occasionally it becomes more or less spotted 

 with diffused reddish spots, which appear to be felspathic. These 

 rocks are bordered on the north-west, west, and south-west by others 

 that are softer and less siliceous, and which are probably derived 

 from the shales. They vary greatly in appearance from black, grey- 

 ish, and greenish-grey porcellanite to dark-green, dark-purple, and 

 red or reddish-brown rocks which show no trace of bedding, and 

 are usually much jointed. Kear the trap they often become imper- 

 fectly granulo-crystalline, or have some minerals, such as nests of 

 radiating crj-stals of epidote or small spherical masses of calcite, &c., 

 scattered through them. In the offstanding hill near Little Malvern 

 the rock is porphyritic, being composed of small, light-coloured 

 crystals of felspar set in an amorphous greenish base ; in the south- 

 east slope of the hill overlooking Castle Morton Common it is a bright- 

 red rock, spotted with green spots ; and in other parts of the area, a 

 variety of semicrystalline rocks occar, which have no very definite 

 character. Many of these variable rocks are probably derived from 

 the ash- and lava-beds that were interstratified with the shales and 

 sandstones, and which have participated in their metamorphism *. 

 Such also is the probable origin of a bluish-grey rock immediately 

 under the southern extremity of the British camp, which appears to 

 resemble very much some of the calcareoxis lava near Bransill Castle 

 and Coal Hill ; and at the extreme southern. point of the area, near 

 a cottage on Castle Morton Common, there are some less altered beds 

 which also appear to be of volcanic character. 



On the northern slope of the offstanding hill south-west of 

 Little Malvern, previously mentioned, there is an unaltered sand- 

 stone containing grains of felspar similar to that of the HoUybusli 

 series on the western declivities of the Eagged-stone HiU ; and in 

 the middle of the long narrow ridge which jets out south of the 

 keeper's lodge there is, among rocks less baked than elsewhere, some 

 black and greenish shale which has undergone but little change ; 



* The clienucal composition of some of these rocks appears to justify this 

 inference. 



