STRUCTURE, BEDDING AND JOINTS OF THE LICKEY QUARTZ ROCK. 495 



lo wish- white, but at Holly Hill, the northern end of the ridge, it is red ; and the separating way- 

 boards are greenish and red siliceous sandstone with sandy schist. 



Wherever the mass has the appearance of quartz rock, the strata are more than usually traversed 

 by joints at right angles to the planes of true stratification, so that if the beds are inclined 20° to 

 the east, the prevalent lines of fissure which are parallel to each other, are inclined 70° to the 

 west. This is seen at the escarpment of Rubury Hill and Snead's Heath ; whilst at that part of 

 the ridge cut through by the old Birmingham road, the beds dip W.N.W. at angles increasing 

 from 20° to 40°, and precisely as this dip varies, so do the rectangular joints change their 

 direction, as expressed in the above sections. To an eye accustomed to rocks of this age, there is 

 little difficulty in distinguishing the true bedding from joint lines, even in those parts of the ridge 

 where the sandstone has most changed its ordinary characters ; and if any doubt should exist, the 

 observer has only to examine the section laid bare by the new road, which, in exhibiting a passage 

 from the quartz rock into the fossiliferous sandstone, dispels all doubt as to the true laminae of de- 

 posit. The consequence of these countless lines of joints, at right angles to the planes of stratifica- 

 tion, is the division of the quartz rock into those small trapezoidal fragments into which the mass 

 shivers, upon being quarried, and in each of which it is so difficult to obtain a fresh fracture. 



In passing from a fossiliferous sandstone into compact, granular and small jointed 

 quartz rock, the Lower Lickey Hills, therefore, exhibit a perfect parallel to those masses 

 which I have shown to be altered sandstones on the flanks of the Wrekin. In those 

 cases we find the altered masses actually plastered upon the sides of rocks of un- 

 questionable volcanic composition, and hence we have inferred, that the sandstone was 

 altered by heat, into a state of quartz rock, more or less crystalline. Now we have 

 almost equally good proof, of a similar metamorphosis in the Lower Lickey Hills ; for 

 on tracing them to their southern termination, we discover, between Kendal End and 

 Barnt Green, a small tongue of trap, of reddish-brown, compact felspar, which emerges 

 directly from beneath them, PI. 37. f. 9. (See Map.) We thus clearly ascertain, that 

 the quartz rock is situated upon a fissure of volcanic eruption. We further see, that 

 the strike of this little ridge is parallel to the major axis of the southern portion of the 

 Dudley coal-field, and also to the direction of the great line of fissure along which 

 the trap of Rowley was evolved. Again, other parallel lines of trappean eruption occur 

 in the Clent and High Lickey Hills, equally proceeding from N.N.W. to S.S.E., and 

 these absolutely flank the quartz ridge, on the N.W. • one of them, the Lickey Beacon, 

 rising to the surface within half a mile of the quartz rock, and running parallel to it. 

 Seeing, therefore, that the prevailing direction of all the fissures of trappean eruption 

 in this tract, as well as of the quartz ridge, is from N.N.W. to S.S.E., or rather on 

 lines varying from 10° to 20° W. of N. ; and further that trap emerges from beneath 

 the quartz rock, there can be no doubt that this singular ridge is on a line of volcanic 

 fissure, through which sufficient heat has been evolved to effect the fusion of the sand- 

 stone. 



These observations lead us naturally to consider the character of the adjacent trap 

 rocks. 



3 q 2 



