2 PROF. A. H. GEEEN ON SOME RECENT [Feb. 1 895, 



Mr. Puitley lias described some rocks from this group. 1 He states 

 in the latter paper that these rocks form ' a buttress faulted against 

 the eastern flank of the Herefordshire Beacon ' (p. 743) ; but he 

 gives no evidence for the existence of the fault. 



Recently a reservoir for supplying water to Great Malvern has 

 been constructed in the valley between Tinker's Hill and Broad 

 Down, and the excavations made in the course of this work have 

 opened out the rocks in question and thrown some little additional 

 light on their character and lie. 



My attention was drawn to these cuttings by Prof. Hughes in 1892, 

 and during the summer of that year I gave some time to a study of 

 them and the surrounding country, with, I fear, slender results ; 

 but, as most of the sections are now covered up, it seemed worth 

 while putting on record what they showed ; and this must be my 

 excuse for troubling the Society with a paper which is little more 

 than a statement of facts, and leads but to meagre conclusions. 2 



The rocks are bedded. In the puddle-trench of the reservoir they 

 strike about north, and are nearly on end. In the cutting for the 

 diverted road along the south-western side of Tinker's Hill the 

 strike is still northerly, but the dip comes down to 75°, and a 

 little farther south-east is only 25°. Whether the same strike is 

 maintained over the whole tract we are concerned with cannot be 

 definitely asserted, for the great bulk of the rocks are very much 

 alike, and no beds occur which have distinctive individuality enough 

 to enable them to be traced with certainty across the open country. 

 In some few cases my attempts at detailed mapping have been 

 attended with qualified success ; and, if my tentative identifications 

 be correct, the general strike is north and south. 



Of the rocks themselves it is impossible to speak with satisfaction. 

 The great bulk of them are hard, closely grained, and splintery, 

 such as could be conveniently grouped in the field under the vague 

 term of ' felsites.' Of these some under the microscope have much 

 that is rhyolitic about them, and are not improbably lavas, some 

 perhaps devitrified glasses. Others are seen to be decidedly frag- 

 mental, and may well be tuffs. They are largely altered, so thickly 

 veined with calcite in many cases that they effervesce freely with 

 acids. This seems to have led some observers to call them lime- 

 stones, but a little attention shows that in nearly all the efferves- 

 cence is confined to the veins. Epidote in veins and disseminated 

 through the rock is also common. 



There are also dolerites, some of which are not unlike the felsitic 

 rocks macroscopicalry, but are clearly characterized under the micro- 

 scope. Whether these are flows or intrusive sheets is an open 

 question ; I rather incline to the opinion that they are intrusive, 

 for, as will appear later on, they seem to be wedge-shaped masses 

 and not continuous beds. 



1 Quart, Journ. Geol. Soc. vols, xliii. (1887) pp. 498, 499, & xUV. (1888) p. 740. 



2 I acknowledge, with many thanks, the assistance which I have received from 

 my friends, Mr. Rutley and Mr. Teall, in my examination of the rocks dealt 

 with in this paper. 



