Reportis ami Proceedings — Geoloylcal Sooieti/ of London. OS- 

 discursive book is intended. " Of the making of books there is no 

 end," and there is a real need for accurate and thorough work 

 on local geology and scenery, but a treatise of very elementary 

 theoretical geology is quite another thing. W. II. 



I^.EI=•OI^Ts j^isTiD :F>i?,OG:BEiDiisra-s. 



Geological Society of London. 



I.— December 19, 1900.— J. J.H. Teall, Esq., M.A., F.R.S., President, 

 in the Chair. The following communications were read : — 



1. " On the Igneous Eocks associated with the Cambrian Beds of 

 the Malvern Hills." By Prof. T. T. Groom, M.A., D.Sc, P.G.S. 



The Cambrian beds of the Southern Malverns are associated with 

 a series of igneous rocks which have commonly been regarded as 

 volcanic, but are probably all intrusive. They consist of a series- 

 of bosses, dykes, sills, and small laccolites intruded into the Upper 

 Cambrian Shales and into the Hollybush Sandstone. The dykes 

 appear to be confined to the sandstones, the sills and laccolites- 

 chiefly to the shales, while the bosses are found in both. The rocks 

 consist of a series of ophitic olivine-diabases, a related series of 

 porphyrltic olivine-basalts, and a series of porphyritic amphibole- 

 bearing rocks of andesitic habit, but probably to be classed with 

 the camptonites. The three types have a different distribution, and 

 do not appear to be connected together by intermediate gradations ;. 

 the amphibole-bearing and the olivine-bearing rocks differ in their 

 mode of occurrence. According to existing analyses, the former 

 range in chemical composition fi'om sub-basic to basic, and the latter 

 from thoroughly basic to ultrabasic. All the rocks have a local 

 stamp, but are probably most nearly related to the camptonitie 

 rocks of the Central English ]\Iidlands. Intrusion took place at 

 a period not earlier than the Tremadoc, and probably not later 

 than that of the May Hill Sandstone. 



2. " On the Upper Greensand and Chloritic Marl of Mere and 

 Maiden Bradley in Wiltshire." By A. J. Jukes-Browne, Esq., B.A., 

 F.G.S., and John Scanes, Esq. 



The district dealt with is on the borders of AViltshire and 

 Somerset. The general succession is as follows : — 



feet. 



Lower Chalk, with Chloritic Marl at the hasc "200 



Sands with calcareous coucretions ... ... ... 3 to 8 



Sands with siliceous concretions (cherts) 20 to 24 



Coarse Greensand ... ... ... .-• ... ... l-""' 



Fine f^rey and huff sands about 120 



Sandy niarlstone 1& 



Grey marl and clay (Gault) 90 



The chert-concretions and the sands in which they occur consist 

 very largely of spicules of lithistid sponges. One of the sandstone- 

 beds has yielded several species of Necrocarciuns, and may be the- 



