TRANSACTIONS OF SECTION C. 739 



of the materials of the Hollybush Conglomerate by the author does not support 

 this view. 



The most abundant pebbles consist of quartz ; these vary from a coarse mosaic 

 of crystals to a fine qiuirtz-schist. Most of the varieties are probably of meta- 

 morpbic origin; some appear to be merely vein-quartz, and some represent the 

 quartzose portions of granites and other rocks, lied (jranites and (jvanophyres, 

 often crushed, are tolerably abundant ; these often contain microcline. Mica-schist 

 and chlorite-schist occur rarely. Very abundant are difi'erent varieties of felsite. 

 These appear to be mostly micro- or crypto-crj^stalline, and often micro-graphic, 

 rhjoliten, compact or porphyritic ; sometimes banded, and occasionally spherulitic. 

 Some of the varieties may represent crushed intrusive./'c&jY^'S. Far rarer than the 

 rhyolites are microlithic andesites, or andesitio bamlts. Other pebbles, and the 

 grains of the groundmass, consist of materials derivable from the rocks mentioned 

 above. 



The resemblance of these materials to the rocks of the Malvern Range is suffi- 

 ciently close to prope the Pre-Cambrian age of the latter. But striking differences 

 in microscopic structure and in the proportionate numbers of corresponding rocks 

 in the two series, and the absence of any relation between the local nature of the 

 conglomerate and that of the Archaean mass nearest to it, can hardly be explained 

 except on the assumption that the Range itself did not furnish the materials. 



The stratigraphical relations of the conglomerate and Archaean mass, moreover, 

 appear to indicate that the Malvern Hills — the southern portion at least — in 

 Cambrian times formed part of an area of deposition, and not of denudation. 



The author maintains, then, that the Malvern Hills did not form a coast-line 

 in Cambrian times, a conclusion which is in agreement with his former contention 

 that they arose at a much later date. 



11. On the Igneous Rocks associated with the Cambrian Beds of Malvern, 

 By Theodore Groom, M.A., D.Sc. 



The igneous rocks of the Cambrian beds of the Southern Malverns have 

 commonly been regarded as of volcanic origin. The author, after a careful 

 examination of the rocks under the microscope, and of the ground, concludes that 

 the scoriae and tufis previously described are non-existent, and that the whole of 

 the igneous rocks are probably intrusive. They consist of silts and small laccolites 

 of basic and iiltra-basic olivine diabase and olivine basalt, in which olivine is often 

 extremely abundant, and of bosses and dykes of peculiar amphibole bearing 

 andesites and andesitic basalts. 



Intrusion probably took place in Ordovician times. 



SATURDAY, SEPTEMBER 8. 



The following Papers and Reports were read : — 



1. On a Possible Coalfield in the London Basin. 

 By Professor W. J. Sollas, D.8c., LL.D., F.R.S. 



A very expensive and laborious investigation was undertaken some years ago 

 to determine the dip of the Palaeozoic rocks reached by deep borings at \Vare and 

 Cheshunt. The results were communicated to the Association by Mr. J, Francis 

 on the occasion of its meeting in Ipswich in 1895. At Ware the Silurian strata, 

 which had been reached at a depth of 797 feet, were found to dip nearly due south, 

 at an angle of 41° ; at Turuford, near Cheshunt, Devonian rocks were encountered 

 at 980 feet, and dipped a little to the west of south at an angle of»25°. 



When beds occur in somewhat gently imdulatiug folds, such as those which 

 appear to characterise the Palasozoic rocks of the east of England, the sweep of 



3 b2 



