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PEOF. T. T. GEOOM ON THE GEOLOGICAL [May 1899, 



of the chief exposure of conglomerate an apparent continuation of 

 the ridge, to which allusion has been made, is formed by a small block 

 of Archaean rock, reached by excavations. This appears to join the 

 main zone of the gneissic series which runs down the northern 

 slope of the western side of Eaggedstone Hill, for excavations made 

 to the north of the observed outcrop of the conglomerate indicate 

 that the latter is absent, presumably by faulting out. In conse- 

 quence of the lack of exposures along the line of contact of the 

 conglomerate and this small block, I am unable to say whether the 

 case is one of superposition of the conglomerate on the gneissic 

 series, or whether the junction is merely a fault. An oblique fault 

 running north by west would explain the phenomena observed. 



Pig. 14. — Section in Winter Combe (north side of Raggedstone Hill). 



E. 



(ab is about 52 yards in length.) 



F Archaean 



East of the conglomerate and gneissic rocks, and forming con- 

 siderable portions of the bottom and of the eastern and western 

 slopes of the hollow, is a great mass of Hollybush Sandstone. 

 This, it is true, is nowhere exposed in place, bat its existence is 

 proved by the very considerable stretches of wood covered with 

 debris of nothing but the sandstone. The debris extend up to a 

 height of over 700 feet on the western side of the wood, and in 

 the lower part of the wood the sandstone-area covers a considerable 

 breadth. The western boundary of the mass is indicated by a slight 

 depression just within the wood ; this probably marks a faulted 

 line of junction with the conglomerate, for otherwise the conglo- 

 merate would appear to overlie the sandstone, which there is every 

 reason to doubt. 



This junction appears to continue the curving line of dislocation 

 which traverses Eaggedstone Hill, for Archaean rock occurs not only 

 in the little ridge to which reference has been made, but also in place 

 on the southern side of the road, immediately opposite the entrance 

 to the large quarry. It was reached, I am informed by Mr. Summers, 

 in laying the foundation of the Mission Chnpel, and in excavations 

 made in the gardens for some little distance to the east. It is 

 probable, accordingly, that the Hollybush Sandstone extends down 



