514 Notices of Memoirs — Siviney Lectures on Geology. 



Rhyolite-lavas were extruded during the Raub period, and 

 apparently eruptions of acid rocks and andesites occurred alternately. 

 There is no evidence that rhyolites "were extruded as lavas later than 

 the Raub period, but' eruptions of andesitic composition took place 

 during the formation of both the E-aub and Gondwana rocks, and as 

 the eruptions were in full activity during the formation of the 

 earliest Gondwana beds it is possible that they persisted through the 

 period of dry land. 



All the Raub volcanic rocks that have been examined were 

 evidently deposited under the sea, and such was the case too with 

 the Gondwana volcanic rocks, though in the latter case it is quite 

 probable that for some time the volcanic vents continued to be above 

 sea-level. Radiolarian cherts are associated with Pahang Yolcauic 

 Series rocks at Lubok Plang and on the Main Range in Lower 

 Selangor*, and it is possible that the silica in the sea-water necessary 

 for the building up of Radiolarian tests was supplied by pneumato- 

 lytic emanations from these eruptions. However, no proof of extensive 

 albitization of the Pahang Yolcanic Series rocks is available, and this 

 is a serious drawback to the theory that the two rocks are related in 

 origin. 



The only intrusion of dolerite that was seen on the Pahang 

 Railway was in a weathered railway cutting near the boundary of 

 Gondwanas and Raubs, and it was uncertain whether or not it 

 penetrated Gondwana rocks. There is no proof whether the dolerite 

 is of Raub or Gondwana age. The absence of dolerite boulders from 

 the beach-deposit can be explained by the scarcity of the dolerite 

 outcrops, and does not prove anything about the age of the 

 intrusions. 



NOTICES OF MEMOIRS. 



I. — Swiney Lectures on Geology. 1 



A course of twelve lectures 2 on "The Mineral Resources of the 

 British Empire" will be delivered by Dr. John S. Flett, E.R.S., at 

 the Royal Society of Arts, 18 and 19 John Street, Adelphi, W.C. 



Syllabus. 



Lecture I. Tuesday, November 13. Introductory. — The mineral 

 industries in peace and war. Relation of mineral production to 

 Colonial development. Distribution of minerals of economic value 

 in the British Empire. Trade between Britain and Colonies in 

 minerals, metals, etc., in normal times. Effect of war on mineral 

 production and disti'ibution in the Empire. Statistics of British 

 Imperial production. Resources of the Empire in minerals. 



1 With the sanction of the Trustees of the British Museum (Natural History). 



2 The lectures will be given on Tuesdays, Thursdays, and Fridays at 

 5.30 p.m., beginning Tuesday, November 13, and ending Friday, December 7, 

 1917. To be illustrated by lantern slides. Admission free. 



