328 SECTIONAL TRANSACTIONS— C. 



Sunday, September 4. 



Excursion to the Yorkshire coast {continued). 



Monday, September 5. 



Presidential Address by Prof. P. G. H. Boswell, O.B.E., F.R.S., on The 

 contacts of Geology : the Ice Age and early man in Britain. (See 



P- 57-) 



Joint Discussion with Section H (Anthropology) on The contacts of 

 Geology : the Ice Age and early man in Britain. 



Afternoon. 

 Excursion to Bilborough, Tadcaster, etc. 



Tuesday, September 6. 



Mr. S. Hall and Dr. A. K. Wells. — On rhythmically banded sills at 

 Godolphin, Cornwall. 



The sills described outcrop on the coast between Rinsey and Megaliggar, 

 south-west of the Godolphin granite, south Cornwall. They are doubtless 

 offshoots from the Godolphin qp.ass, and comprise three main sills and 

 numerous smaller ones. The sill-rocks are of granitic composition and are 

 rich in minerals of the pneumatolytic group — tourmaline, topaz, fiuorite and 

 apatite — though there is no reason for believing them to be other than 

 primary constituents. In all of these sills a striking banding, parallel to the 

 lower and upper surfaces, is seen. This is due to pronounced differences 

 in (i) texture, coarsely crystalline pegmatitic bands alternating with finer, 

 aplitic ones ; and (ii) mineral content, there being more or less regularly 

 spaced maxima of coloured mineral, chiefly tourmaline, forming graduated 

 dark bands. A less obvious variation in the quartz/felspar and plagio- 

 clase/orthoclase ratios becomes evident on microscopic examination of 

 serially cut sections. Comparisons are made with other well-known banded 

 rocks, the origin of the banding is discussed, and reasons are advanced for 

 regarding it as due to a rhythmic crystallisation of the magma after flow- 

 movements had ceased. 



Mr. A. T. Dollar. — A study of the granites of Lundy Island, Bristol 

 Channel. 



Lundy is a high rugged island over three miles long and approximately 

 half a mile broad, which lies in the Bristol Channel some twenty-four miles 

 due west of Ilfracombe, off the north-west coast of Devonshire. It consti- 

 tutes part of a small igneous complex, the relations of which to surrounding 

 rock-bodies are problematical. 



About 94 per cent, by volume of the subaerial mass is composed of acid 

 rocks, granite predominating, while the remaining 6 per cent, consists of 

 contorted and contact-altered argillaceous sediments, together with a suite 

 of minor injections, which include banded microgranites, granophyres, an 



