82 PEOCEEDINGS OF THE GEOLOGICAL SOCIETY. 



less gneissoid than in many other parts of the hills, and it appears 

 on the east to pass into a finer-grained rock with much mica and 

 little quartz, while on the western slopes of Summer HiH the mica 

 in part of the rock is replaced by a brownish- coloured paste, rich 

 in peroxide of iron. The want of exposures precludes the opportunity 

 of ascertaining exactly its mode of occurrence with respect to the 

 other rocks, but on the opposite side of the ravine, along the path- 

 way leading to North Malvern, it is seen passing into gneissic rocks*. 



Near the centre of Summer Hill, beyond the granite, is a 

 rather coarse-grained hornblende and Avhite felspar rock, in some 

 parts of which a very small proportion of quartz is added. Beyond 

 this is again granite ; and, at the constricted part of the hill, beneath 

 the pathway to West Malvern is another trap-dyke, which sends out 

 a long branch in the direction of the Westminster Arms Hotel. 



In the three remaining hills, namely, the North Hill, with the 

 Sugar-loaf Hill on the west, and the Terminal Hill to the north of 

 the latter, hornblende enters more generally into the constitution of 

 the rocks than it does in the Worcestershire Beacon. A long trap- 

 dyke crosses the North Hill from north-west to south-east below 

 the south-west side of the summit, and terminates on the north side 

 of the ravine leading from Malvern to West Malvern. Two smaller 

 masses occur a little to the north of this, near the pathway to North 

 Malvern, and a much larger one on the eastern slope of the hill above 

 Hollymount House. Two smaller ones occur higher up the hill 

 overlooking Trinity Church, and another at the summit, Avliich is 

 prolonged south-easterly and occupies the upper portion of the ex- 

 cavation in the hill-side facing the town. On the south-west side 

 of the first-mentioned dyke, the rocks are chiefly gneissoid granite 

 with some diorite, the latter occasionally containing a little quartz in 

 addition to the felspar and hornblende f. On the north side of the 

 dyke the greater portion of the rocks consists of hornblende and fel- 

 spar, or of small-grained felspar and mica rock, with little or no 

 quartz. Sometimes a little quartz is added to the former, and occa- 

 sionally a little hornblende to the latter. At other times the rock 

 is a quaternary mixture of felspar, hornblende, quartz, and mica. 

 Eocks of this variable character especially prevail about the summits 

 On tbe eastern slopes some narrow bands of coarser-grained granite 

 are interstratified, some of which, facing the town, alternate with 

 beds of syenite ; and, towards its north-eastern face, there is much 

 rather coarsely crystallized hornblende and felspar rock, in which 

 the latter is partly pinkish and translucent, and partly of a dead 

 white colour, and has the constitution of a basic felspar. Towards 

 the point of the hUl, at North Malvern, the rocks are chiefly thick- 

 bedded gneiss, often containing much dark-green mica, and occa- 



* Alluding to tliis granite or granitoid rock, Mr. Horner observes, the ma- 

 terials are in some places so disposed as to give the rock somewhat the appear- 

 ance of gneiss (Trans. Geol. Soc. § 26. p. 295). 



t The rock might then be called syenite, but the quartz appears to be only 

 a local and inconstant addition to the hornblende and felspar. 



