142 PKOF. T. T. GROOM ON THE GEOLOGICAL [May 1 899, 



The general relations of the Archaean rocks of Eaggedstone, 

 Hollybush, and Midsummer Hills to their flanking deposits, and the 

 mutual relations of the latter one to another on the slope of the 

 hills, have now been considered ; and it has been shown that these 

 hills consist of a number of faulted blocks. Since the rocks of 

 the formations concerned are everywhere separated by faults, 

 it follows that no proof of the relative order of superposition 

 of these formations can be given from the area considered. 

 I^evertheless the axial position of the gneissic series, and the 

 prevalent order of proximity of the remaining formations, clearly 

 suggest the generally received order of superposition in the district. 

 The conglomerate and quartzite are found only in contact with the 

 gneissic series ; the Black Shales are generally more remote from 

 the axis ; while the Hollybush Sandstone occupies an intermediate 

 position, and the superposition .of the May Hill Sandstone on the 

 shale series is fixed by evidence from other parts of the area described 

 in these pages. 



(3) The Central Depressions in the Hills of the Southern 

 Part of the Range. (Figs. 11-15.) 



It was long ago observed by Phillips ^ that the Malvern range 

 was on the whole a single chain of hills, but that certain hills, 

 such as Eaggedstone Hill and the joint mass formed by Mid- 

 summer and Hollybush Hills, showed two summits placed side by 

 side. HoU pointed out later ^ that in the case of Eaggedstone Hill 

 the eastern and western sides differed in structure and lithology, 

 and he recognized the existence of a fault running down a part 

 of the depression between the two halves. This deduction was 

 confirmed by Mr. Eutley.-^ Apart from these, I am unaware of any 

 observations bearing on longitudinal structural differentiation of the 

 Archsean axis. 



Now, the magnitude of the depressions which occur along the centre 

 of Eaggedstone Hill, and between Midsummer and Hollybush Hills, 

 appeared to me too great to be explained by a simple fault. I 

 therefore suspected the existence of softer or more easily denuded 

 masses in the middle of the gneissic series, introduced, possibly, by 

 earth-movements. A careful examination of the hollows showed 

 that this conjecture was correct. 



The hollow on the southern side of Midsummer Hill (see PI. XY) 

 is bounded by two steep slopes, and has a somewhat sharply- defined, 

 rather flat bottom, sloping down towards the south-south-west. 

 The gneissic rocks descend to the level of this floor. The floor 

 itself is covered with turf, and no rock is exposed in place : but 

 excavations made in former days, during the construction of the 

 three old British reservoirs, and of the trench of the camp at the 



1 Mem. Geol. Surv. vol. ii (1848) pt. i, pp. 9, 11, 26. 

 - Qimrt. Journ. Geol. See. vol. xxi (1865) p. 74. 

 3 Ibid. vol. xliii (1887) p. 488, figs. 1 & 2. 



