152 . PROF. T. T. GROOM ON THE GEOLOGICAL [Feb. I9OO, 



The Silurian rocks immediately west of the Worcestershire Beacon 

 and North Hill have few and slight transverse dislocations. The 

 only conspicuous fault is one which dislocates the Woolhope Lime- 

 stone west of the Dingle : this fault is shown in Holl's map. 1 

 Mr. Rutley represents it as continued up the Dingle across the 

 Archaean rocks. 2 A curious circumstance in this connexion is the 

 occurrence of debris of May Hill Sandstone some little way up this 

 depression, as though May Hill Beds had been squeezed into an 

 open cleft. Prof. Hughes informs me that he has noted the same 

 fact. The fault, however, does not dislocate the main western 

 boundary- fault of the Archaean massif at this point, a circumstance 

 which suggests that the former fault affords an instance of move- 

 ment along an old line of dislocation. 



North Hill affords a couple of interesting cases of what appear 

 to be thrusts within the Archaean massif itself. These are seen 

 close to the main western thrust, of which possibly they are 

 branches. One of these thrusts is exposed in a quarry north of 

 St. Edward's Orphanage. The relations seen are represented in the 

 accompanying section (fig. 7, p. 151). 



On the eastern side are Archaean rocks, the folia of which dip 

 south by east at about 70° ; these are separated from a slip of 

 crushed, grey, shaly May Hill Sandstone by a loose breccia, evidently 

 marking a fault-plane. The fault dips south-eastward ; the sand- 

 stone-beds, perhaps about 4 yards in thickness, also dip south- 

 eastward at 60°. West of this is seen a slip of Archaean rock not 

 markedly foliated, from 2 to 5 yards broad, and partly covered by 

 detritus, which also conceals the main fault on the western side of 

 the slip. Immediately west of this detritus sandstone is again seen, 

 followed in the neighbouring garden by the vertical purple grits to 

 which reference was made on p. 150 ; these strike approximately 

 north-north-east. Farther down the slope is seen the inverted 

 Woolhope Limestone. It may be noted that the foliation of the 

 Archaean rocks tends towards parallelism with the thrust-plane and 

 with the dip of the sandstones. 



A most interesting section was formerly to be seen in a small 

 quarry close to the eastern side of the upper road, at a point about 

 due north-east of the Lamb Inn. 3 On the south-eastern side of the 

 quarry greenish micaceous May Hill Sandstones, apparently belong- 

 ing to the upper part of the formation, strike 15° east of north ; 

 the prevailing dip is towards the western side, at angles varying 

 from 60° to 80° ; but at the top of the quarry the sandstones bend 

 over, so as to dip in the opposite direction, at angles commonly 

 ranging between 70° and 0°, the beds towards the south-western 

 end of the quarry being horizontal. The axis of the fold appears to 



1 Quart. Journ. Geol. Soc. vol. xxi (1865) p. 95. 



2 Ibid. vol. xliii (1887) map facing p. 488. 



3 This quarry, seen by Mr. H. D. Acland and the writer, has now unfor- 

 tunately been vised as a building-site, for a house named ' Valley View.' The 

 rocks have been almost entirely concealed within the last few months. 



