66 



SCIENTIFIC NEWS. 



Qan. 20, I? 



ABSTRACTS of PAPERS, LECTURES, etc. 



GEOLOGICAL SOCIETY. 

 At the, meeting held on December 21st, 1887, Prof. J. W. 

 Judd, F.R.S., President, in the chair, the following com- 

 munications were read : — • 



I. "On the Correlation of some of the Eocene Strata 

 in the Tertiary Basins of England, Belgium, and the 

 North of France." By Prof. Joseph Prestvvich, M.A., 

 F.R.S., F.G.S. 



Although the relations of the several series have been 

 for the most part established, there are still differences of 

 opinion as to the exact relation of the Sable de Bracheux 

 and of the Soissonnais to the English Series ; of the 

 Oldhaven Beds to the Woolwich Series ; and of the London 

 Clay and Lower and Upper Bagshots to equivalent strata 

 in the Paris Basin. The author referred to the usual 

 classification in the Eocene Series, and proceeded to deal 

 with each group in ascending order. 



The Calcairc de Motis is not represented in England, 

 but may be in France by the Strontianiferous marls of 

 Meudon. It contains a rich molluscan fauna, including 

 300 species of Gasteropods, many of which are peculiar, 

 but all the genera are Tertiary forms. The Heeysiaji are 

 beds of local occurrence, and the author sees no good 

 reason for separating them from the Lower Landenian or 

 Thanet Sands He gave reasons for excluding the Sands 

 of Bracheux irom this group. Out of 28 Pegwell Bay 

 species, 10 are common to the Lower Landenian, and 5 

 to the Bracheux Sands, which present a marked analogy 

 with the Woolwich Series. These Sands of Bracheux are 

 replaced in the neighbourhood of Paris by red and 

 mottled clays. Out of 45 species at Beauvais only 6 are 

 common to the Thanet sands and 10 to the Woolwich 

 Series. Out ot 75 species in the Woolwich and Rending 

 Beds, 19 occur in the Bracheux Beds, it we add to these 

 latter the Sands of Chalons-sur-Vesles. 



Respecting the Base-.nent Bed of the London Clay 

 {Oldhaven Beds in part), the author would exclude the 

 .Sundridge and Charlton fossils, which should be placed 

 on a level with the Upper Marine Beds of Woolwich. He 

 allowed that the former were deposited on an eroded 

 surface, but this involves no real unconformity, whilst 

 the palasontological evidence is in favour of this view 

 since out of 57 species in the Sundridge and associated 

 beds, only 16 are com— on to the London Clay. He 

 therefore objected to the quadruple division. Either the 

 Oldhaven should go with the Woolwich or with the Base- 

 ment Bed. He admitted that the term " Basement Bed " 

 is objectionable, and preferred Mr. Whitaker's term for 

 the series, as he would limit it. 



The Lower Bagshot Sands. — The author would call 

 " London Sands," whose Belgian equivalent is the Upper 

 Ypresian, and the French the Sands of Cuise-la-Motte, 

 forming the uppermost series of the Lov/er Eocene. A 

 group of fossils has been discovered in the Upper 

 Ypresian sands of Belgium., vv-hich leaves no doubt of 

 their being of Lower Eocene age, and consequently the 

 Lower Bagshots must be placed upon the same horizon. 

 There is no separating line of erosion between the 

 London Clay and the Lower Bagshots, the upper part of 

 the former is sandj', and the lower part of the latter 

 frequently argillaceous. Similarly no definite line can 

 be drawn between the Upper and Lovrer Ypresian ; but 

 in both countries this series is separated from overlying 

 beds by a well-marked line of erosion. So also in France 



the base of the Calcaire Grassier (Bracklesham Beds) is 

 a pebbly green-sand resting on an eroded surface of the 

 Sands of the Cuise-de-la-Motte. In Belgium, in White- 

 clift" Bay, and in the Bagshot district the Upper Eocene 

 rests upon an eroded surface of the Lower Eocene. 



2. " On the Cambrian and Associated Rocks in North- 

 west Carnarvonshire" By Prof. J. F. Blake, M.A., 

 F.G.S. 



After referring to the published views of Professor 

 Sedgwick, Sir A. C. Ramsaj', and the Geological Survey, 

 Profs. Hughes and Bonnej- and Dr. Hicks, concerning the 

 area in question and especially as to the presence or 

 absence of Pre-Cambrian rocks, the author gave an account 

 of his own explorations and their results, the principal 

 of which were the following : — 



In the Bangor and Carnarvon area three distinct con- 

 glomerates had been confounded. The only one that 

 showed distinct unconformity on the underlying rock was 

 of Arenig (Ordovician) age. The rocks of the southern 

 and central portion of the area were essentially of igneous 

 origin and might be distinguished into two groups, the 

 southern probably intrusive, the northern certainly erup- 

 tive. There is no evidence to show what interval of 

 time elapsed between the production of these two groups 

 nor which of them is the earlier, although the author 

 regards it as more probable that the southern mass is of 

 the earlier date and overlain bj' the northern portion. 

 The Bangor beds are derived from the denudation of the 

 volcanic series, and of rocks which may have been asso- 

 ciated with it, and thej' contain a series of conformable 

 conglomerates, of which the great conglomerates near 

 Bangor are members. They are the continuation of the 

 Cambrian rocks seen to the east, and have not undergone 

 any serious alteration. The porphyries of Llyn Padarn 

 and Moel Tryfaen are contemporaneous lava-flows in the 

 midst of the Cambrian Series, the overlying conglomerates 

 being derived from them and from the sedimentary 

 Cambrian rocks to the west : and hence there is no 

 certain proof of there being any Pre-Cambrian rocks in the 

 whole district, though it is probable that the rock near 

 Carnarvon belongs to an epoch distinct from and ante- 

 rior to the Cambrian. 



EDINBURGH PHILOSOPHICAL INSTITUTION. 

 The Hon. Ralph Abercrombie recently delivered a lec- 

 ture on " Cloudland in Folklore and in Science." The 

 lecture was illustrated by limelight photographic views of 

 the various species of clouds to which reference was made. 

 His purpose, the lecturer stated, was to examine the 

 ideas which the forms of clouds had suggested to dif- 

 ferent nations, and to make some reflections on the atti- 

 tude of mind induced by the ancient or figurative poetic 

 waj' of looking at things as compared with the modern 

 scientific spirit. Cloud form.s were the same all over the 

 world, and there were only six or seven essentially dif- 

 ferent types of cloud-structures. There were many inte- 

 resting survivals of the old way of regarding clouds ; the 

 well-known hairy or fibrous structure, for example, which 

 formerly suggested, to the Greeks hairy monsters and 

 chimeras, w-ere now known as goats' hair or mares' tails. 

 The fleecy structure formerly held as resembling flocks of 

 heavenly sheep was still called by such names as 

 " wool-pack " and " mackerel sky," while the rocky, 

 cumulus cloud, which once suggested the idea of many- 

 headed monsters, was now in certain cases called 

 " thunder-heads," " wind dogs," or " boars' heads." The 

 peculiar hairy structure in front of heavy masses of 



