268 



REPORTS. 



5. — Corbiere, Forest. 



Porphyritic gneiss with numerous veins of felsite and 

 diorite is here found. One of these veins at the foot of 

 the cliff, weathered white, and had altogether an appearance 

 different from the others, suggesting aplite. 



6. — Mont Cuct. 



In a quarry near the martello tower a raised beach at 

 50 feet elevation has been noted in close proximity to the 

 deposit at 25 feet elevation previously noted. 



7. — Maison de Bas, Vale. 



Another exposure of the 50 ft. beach is seen in the 

 quarry behind the above house. 



A paper was read before the Geological Society of 

 London on the 22nd November, 1911, by Professor Bonney 

 and the Reverend Edwin Hill, containing their latest views 

 on the rocks of Guernsey, and the other islands of the 

 Bailiwick. One of their conclusions was that there existed 

 in Guernsey and Alderney a dioritic magma, which underwent 

 differentiation from basic rocks, such as Bon Repos in 

 Guernsey and Fort Albert in Alderney, to the so-called 

 granites, which they suggested might be the more acid terms 

 of a differentiation series. 



The well-known mass at Pleinmont resembling greenstone 

 had been proved to be sedimentary, and was considered to be, 

 like the Jersey argillites, of Brioverian age (this term is 

 derived from the ancient name of St. L6). The gneiss of 

 Guernsey, a pressure modified granite, was considered by the 

 authors to be the oldest rock in the island, followed in suc- 

 cession by the diorites, the hornblendic granites and the aplitic 

 microgranites. Then came the diabase dykes and the quartz 

 felsite dykes, which may possibly be of the same age as 

 the acid lavas below the Jersey conglomerate, although in 

 Alderney diabase dykes cut the Gres feldspathique (sand- 

 stone). The mica traps are probably late palaeozoic. 



C. G. De La Mare, Sect. Geol. Sect. 



Report of the Marine Zoology Section, 1911. 



At present this is a section without workers ; con- 

 sequently there is, unfortunately, but little to report this 

 year. 



