91 



running from north-east to south-west, which forms the chief rider 

 to those veinSj as in the case of the Stiper Stones in Shropshire. 



II. Mnivern and Ahherley Hills. — The author highly commends 

 the description of the Malvern Hills published by Mr. Horner in the 

 Geological Transactions*, and refers to it for a faithful account of 

 their mineralogical structure. The present memoir dwells more at 

 length on the effects produced by these sienitic rocks upon the 

 grauwacke strata among which they have been protruded, and which 

 have been altered into chloritic and micaceous schists, highly indu- 

 rated grits, &c. ; whilst others, although unaltered, have been thrown 

 into an inverted position, as pointed out upon a former occasion-)-. 



The author points out the existence of certain bosses of sienite 

 and greenstone in Cowley park to the north of the main chain. 

 He then proceeds to indicate the various points at which masses of 

 eruptive rock hitherto unnoticed appear at the surface in the north- 

 ern prolongation of the direction of these hills, and connect the 

 Malvern with the Abberley Hills. These are the hills of Berrow, 

 Woodbury and Abberley. They are all of rounded forms, and so 

 covered with vegetation that their structure can only be ascertained 

 from the knobs of rock which occasionally protrude. They chiefly 

 consist of concretionary, compact felspar, sometimes containing 

 crystals of common felspar. That they have, however, a mineral 

 nucleus similar to that of the Malverns, is to be inferred from two 

 observations: 1st. The discovery at the north end of Berrow Hill of 

 a small boss of rock having quite a granitoid character, being made 

 up of compact felspar, quartz and silvery mica, and therefore undi- 

 stinguishable from a sienite of the Malverns. 2ndly. The discovery 

 of a remarkable dyke at Brockhill, on the right bank of the river 

 Teme, Worcestershire. This dyke is evidently a spur from the trap- 

 pean hills of Woodbury and Abberley, from the first of which it is 

 distant only 1^ mile, being thrown out in a direction from east to 

 west. The dyke cuts through the old red sandstone, and consists 

 chiefly of sienite or sienitic greenstone perfectly analogous to many 

 varieties of the Malvern Hills. It is in great part columnar, the ends 

 of the columns being at right angles to the walls of the dyke. The 

 strata in contact with the trap are much hardened; ihe mica appears 

 to be driven off from the sandstone, the colour of which is changed 

 to a dingy dark purple; and the associated marls and cornstone are 

 converted into hard amygdaloids, with veins of carbonate of lime, 

 crystals of iron pyrites, &c. &c. 



Another dyke of trap traversing the old red sandstone, which is 

 marked in Mr. Greenough's map, occurs at Bartestreenear Hereford. 

 It is a basaltic greenstone, with olivine, and the strata in contact are 

 affected similarly to those of Brockhill near Abberley. 



III. Trap Rocks penetrating the Coal Measures. 



Clee kills. — The basalt of the Titterstone and Brown Clee Hills 

 having been described, the author only refers to his former com- 

 munications for the purpose of stating, that Mr. Lewis of Knowlbury 



* Geol. Trans., Ut Series, vol. i. p. 281, 

 f Ante, p. 1«. 



