182 Mejjorts and Proceedings — 



The author stated that nothing had heen -written on this subject since Prof. 

 Prestwich's paper, in which the beds at Hengistbury were described as of the Barton 

 series. No attempt had hitherto been made to correlate the beds at Alum Bay or 

 Whitecliff Bay with those of the mainland, and no reference was to be found any- 

 where to the origin and sequence of the beds between Hengistbury Head and 

 Boui'nemouth, or to theu* contained fossils. He had now correlated these bed for 

 bed with the strata at Alum Bay, and found that there is a sequence, and that the 

 llengistbui-y beds are higher than those of Bournemouth and do not reappear on 

 the coast. They are all of marine origin and were deposited by a sea advancing 

 from the south, as is shown by the slope of the shingle beds and the lenticular 

 patches of clay which mark old channels parallel to the former shore and at right 

 angles to the present eliff-line. They contain numerous fossDs, fruits, leaves, 

 Mollusca, and Crustacea, the fruits resembling those of Sheppey and forming a 

 group of similar character. The Mollusca are of Bracklesham type, and the fossils 

 include three genera of Bryozoa, two of which are new to the Eocene. The 

 Crustacea have not yet been examined. 



The author comes to the conclusion that the whole group is contemporaneous with 

 the Bracklesham beds, and is not of Lower Bagshot age. Similar shore-conditions 

 probably extended into the London basin, and the beds mapped by the Survey as 

 Lower Bagshot are probably of the same age as those at Boscombe, in which case 

 nothing more than the Bracklesham is to be met with in the London basin. The 

 similarity of the leaves, etc., from Bovey Tracy to those obtained by the author leads 

 him to infer that the former also are of Eocene, and not of Miocene age. The 

 author increases the thickness of the London Clay at Alum Bay at the expense of 

 the Bagshot beds, and diminishes that of the Bracklesham beds at Whitecliff Bay 

 by transferring part of them to the Lower Bagshot. 



3. "Notes on Certain Modes of Occurrence of Gold in Australia." By Richard 

 Daintree, Esq., F.G.S. 



The author stated that he had in a previous paper (Q. J. G. S. vol. xxviii. p. 271) 

 proved the occurrence of gold in the Devonian rocks of Queensland, and further that 

 the auriferous tracts were certainly confined to those districts in which the Devonian 

 rocks were penetrated by certain plutonic rocks, principally pyritous diorites. These 

 conclusions had since been confirmed by Mr. "W". C. Wilkinson and Dr. G. F. H. 

 Ulrich ; and the facts thus established are of the greatest practical importance to 

 miners. With regard to the epoch when the auriferous pyrites was deposited in the 

 rocks, the author expresses the opinion that most of the pyrites is contemporaneous 

 with the consolidation of the rocks in which it occurs, although some may have been 

 subsequently introduced by infilti-ation ; but this is not common in Australia. A 

 more common case is the separation of gold generally diffused through a rock into 

 local fissures, forming strings and veins. The author thinks that all the evidence 

 goes to show that the Australian auriferous veins were chiefly formed during the 

 earliest era of great volcanic agitation indicated by the condition of the stratified 

 rocks, namely the Devonian, but that they were enriched during a subsequent Tertiary 

 (probably Miocene) period of intense activity. No traces of auriferous veins have 

 yet been found in any Mesozoic or Cainozoic deposits in Australia. 



4. "Notes on the Geology of the Island of Mauritius and the adjacent Islets." 

 By W. H. T. Power, Esq., B.A. (Communicated by W. Whitaker, Esq., B.A., 

 F.G.S.) 



The author stated that the island of Mauritius consists of an elevated central 

 plateau, bounded by an incomplete wall of volcanic rock, round part of which there 

 is a coral reef and coral sand-rock, and also rocks of various coloiu-s produced by the 

 decomposition of volcanic rocks. Outside is a living coral reef. In the middle of 

 the island the old crater-wall can be distinguished, although broken ; two secondary 

 craters are also noticed. On the north slope of the island there is a flow of columnar 

 basalt to the sea. There is an opening in the old coral-reef, as in the existing one 

 opposite the mouth of the Black Biver. Gabriel Island consists of a coral reef and 

 detrital coral rock upon a foundation of basalt, the section showing in descending 

 order: — 1. Coral stone; 2. Conglomerate of coral, vrith some basalt pebbles and 

 shells ; 3. Compact limestone, with thin layers of basalt at base. The author de- 

 scribed the supposed fossil trees noticed in this island by Messrs. Ayres and Clarke 

 (Q. J. G. S. xxiii. p. 185) as composed simply of hard portions of coral rock left 

 outstanding by the weathering of the softer intervening parts ; they show the same 



