^Ol. 55.] STRUCTURE OF THE SOUTHERN MALVERNS. 



143 



top, resulted in the throwing out of some of the rocky bed of 

 the floor. The debris from the middle reservoir consist chiefly, 

 or solely, of fine-grained quartzite and conglomerate (M 169), 

 which can be unmistakably recognized as belonging to the Holly- 

 bush Quartzite series. Immediately above the reservoir, frag- 

 ments of purple Llandovery Sandstone and Grit were numerous 

 (M 168) : these occurred as far up the hollow as the uppermost 

 reservoir, where the fragments were most numerous (M 167). 

 Typical purple Llandovery Sandstone was also found close to the 

 trench at the top of the hollow (M 166). 



Pieces of Llandovery Sandstone (M 174), including a large block 

 with StricJcIandinia li- 



rata^ Atrypa reticularis^ Fig. 11. — Diagrammatic section, showing 

 Pentamerus (?), OrtJiis, the junction ofArchcean and Llandovery 

 Le-ptcena (l)^ and Tentacu- strata in the Hollyhush Pass, 

 lites angliciis, were found 

 at the top of the hollow 

 at the northern end of 

 Hollybush HiU, and 

 other fossiliferous frag- 

 ments were obtained in 

 the trench immediately 

 above it. Phillips re- 

 marks ^ with reference 

 to this hill :— ' It is 

 somewhat singular to 

 find pieces of fossilifer- 

 ous Caradoc sandstones 

 amongst the loose masses 

 of the camp-mounds.' 



Now, there are no 

 rocks on the higher parts 

 of the hill from which 

 these fragments could 

 have been derived by 

 gravitation, and it is 

 hard to believe that their 

 position can be due to an 

 upward movement of ice 

 from lower levels, more 

 particularly as there is, 

 so far as 1 know, no proof 

 of the existence of glacial 

 conditions over the Mal- 

 vern Eange. The only possible explanation is, I think, that slips 

 of the Hollybush Conglomerate and May Hill Sandstone occur 

 beneath the turf and debris ; and that the hoUow, in part at any 

 rate, owes its existence to the excavation of the easily-denuded 

 materials of these formations (see fig. 10, p. 141). 



1 Mem. Geol. Surv. vol. ii (1848) pt. i, p. 28. 



Fi^= Fault. 



e=: Decomposed pui-- 



ple sandy rock. 



d = Yellow sand stone ; 



4 inches thick. 

 c=Blue clay; 10 

 inches thick. 



b = Green and yellow 

 sandy shales, 

 with traces of 

 crinoids ; 18 

 inches thick. 



a=Arch£ean (dio- 

 rite). 



