43Q 



NA TURE 



\_August 31, 1882 



with beds of ihe same age in Fiance, Belgium, and Germany, 

 cannot be overlooked or over-estimated, and often as it has been 

 attempted, the papers by the two above-named authors have still 

 greatly added to our know ledge of the stratigraphy of the Eocene 

 series of the Isle of Wight. It is impossible to dispute the 

 validity of their researches and value of their sections. The 

 publication of Mr. Judd's paper disputing the correctness of 

 Forbes's work and that of the Geological Survey, and the pro- 

 posal of a fresh classification, drew immediate attention to the 

 labours of the older authors, but especially that by the Geological 

 Survey — which was answerable for the latest, indeed the only 

 known extended and complete analysis of the Upptr Eocene 

 strata of the I.-le of Wight. 



We owe a debt of gratitude to the late Mr. F. Edwards and 

 Mr. S. V. Wood, for tneir valuable additions to our knowledge 

 of the palaeontology of the fauna of the fluvio-marine beds of the 

 Hampshire basin. Since the publication of Professor Forbe.v's 

 memoir upon the Isle of Wight, the molluscan fauna alone is at 

 least three times as great as noticed by him, and since which the 

 remarkable fauna of -Brockenhurst in the New Forest, discovered 

 by Mr. Edwards, has been carefully studied by Von Konen for 

 the mollusca, and Dr. Duncan for the corals. These naturalists 

 have shown the relation an 1 agreement of this faunawith that of 

 the Lower Oligocene in North Germany. This Brockenhurst 

 fauna is also identical with certain strata at the base of the 

 Middle Headon beds at Whitecliff Bay, in the Isle of Wight. 



Professor Judd ill his paper de cribes the s'ratigraphical 

 positi m of the Colwell Bay and Headon Hill beds, and their 

 relation to each other, pointing out what he believed to have been 

 an error on Forbes's part, relative to the correlation of the " Venus 

 bed" at two places, in what is really a continuous section, 

 Edward Forbes and the Geological Survey having carefully and 

 correctly determined that only one set of marine strata occurred 

 between the two brackish or estuarine and freshwater series. 

 This fact has been again most carefully worked out by Messrs. 

 Tawney and Keeping, having no doubt as to the interpretation 

 and accuracy of the work of Forbes and the Survey, and estab- 

 lishing upon a firmer basis the continuity and equivalency of the 

 Colwell Bay and Headon Hill marine series, through the "Venus 

 bed," all being stratigraphically and pulaeontologically the same. 

 Professor Judd insists upon 250 feet of strata intervening 

 between the Bembridge liuie tone and the marine band of Headon 

 Hill, but Forbes and the Geological Survey in their section 

 show less than one half of that thickness. Recent research con- 

 firms this view. At pp. 14S-150, the author also endeavours to 

 how that palseonlological evidence is in accordance with, and as 

 complete as the stratigraphical. This of course is based upon 

 the belief that both are read or interpreted rightly. The com- 

 parison is between the collective fauna of Whitecliff, Colwell 

 Bay, and Brockenhurst on the one hand, and Htadon Hill and 

 Hordwell on the other hand, but Messrs. Keeping and Tawney 

 have show n the illogical nature of conclusions drawn from such an 

 admixture of beds. Each bed should be compared separately. 



Professor Judd (on pp. 150-164) correlates the British fluvio- 

 marine strata with that of the Continent, adding at p. 153 of 

 this paper a li-t of his so-cdled Brockenhurst species from 

 Whitecliff Bay, Colwell Kay, Brockenhurst, and Lyndhurst, 

 with those species common to the Barton beds below and Hemp- 

 stead series above. This so-called Brockenhurst, but really 

 Middle Headon fauna, numbers 84 genera, and 187 species (6; 

 are MS. names). Four of the 13 corals of the Brockenhurst 

 beds also occur in, or are representatives of the Oligocene stra a 

 of North Germany. This conclusion was arrived at by Dr. 

 Duncan, independently of the work of Von Konen upon the 

 mollusca in the same beds. 1 The author also prepared a list of 

 the Hempstead or so-called Middle Oligocene fauna, in which no 

 less than 40 genera and lot spee'es are named, 40 of these are 

 manuscript names, by Mr. F. Edwards, thus reducing the de- 

 scribed fauna to 61 species. The sub-division and nomenclature 

 of the series is next given, and the author proposed to extend 

 the " name of the Headon series, so as to embrace all the beds 

 between the Barton and the Brockenhurst series, and to call all 

 those strata said to belong to the zone of Ceri/hium concavum 

 the Headon group," doing away with the smaller subdivision of 

 Lower, Middle, and Upper. To all the beds between the 

 Brockenhurst and Hempstead series Mr. Judd w. uld apply the 

 name Bembridge group ; including the series both above and 



1 A. v n Konen on "The Correlation of the Oligocene Deposits of 

 Belgium, Northern Germany, and the South of England." Quarterly 

 Journal the Ceo 'eeie.it Society, vol. inc. p. 97. 



below the "Bembridge series of Edward Forbes, and also beds 

 referred by him to the base of the Hempstead, the Osborne and 

 St. Helen's, and to the Upper Headon." Such a proposal 

 labours under the error of altogether failing to recognise the 

 position which the Brockenhurst fauna occupies in this interesting 

 series. Professor Judd in fact places the Brockenhurst beds not 

 only above the Middle Headon, but above the Upper Heado 1 

 and Osborne beds of Headon Hill. It occupies, however, in 

 fact, a place at the base of the Middle Headon, as is well seen 

 at Whitecliff Bay, and Brockenhurst itself. 



This change in the nomenclature and classification has not 

 met with approbation, and is strongly opposed by Messrs. 

 Tawney and Keeping in their exhaustive paper, and by Mr. 

 Lucas in his con>munication to the Geological Magazine, (Geologi- 

 cal Magazine, decade ii. vol. ix.) Me-srs. Keeping and Tawney 

 elaborately defend the labours and views of the Geological 

 Survey, giving a mass of evidence, both as to the order of the 

 strata and the distribution of life forms, clearly showing that the 

 relations of the whole group can 1 e determined by examination 

 of the continuity of the Colwell Bay and Headon Hill beds, and 

 that the brackish marine beds of Colwell Bay correspond with the 

 brackish marine beds of Headon Hill in every essential particu- 

 lar, being, in fact, one continuous and unbroken sequence, as 

 laid down by the Geological Survey, and which the author- have 

 again so clearly demonstrated in the text rf their Memoir, and 

 laid down in their clear and continuous section from Cliff End 

 or Lynchen Chine to near Alum Bay Chine, and synthetically 

 proved in their vertical sections. 



The following general and condensed description rr analysis 

 of the Headon series of HolwellBay and Headon Hill, as given 

 by Messrs. Tawney and Keeping, will aid those wishing to 

 examine the section, prior to reading or possessing themselves of 

 the original paper in the Quarterly Journal of the Geological 

 Society, vol, xxxvii. or that of Professor Judd, he, cit.. Note I. 



Vertical Section at the North-cast Corner of Headon Hill. — 

 One hundred and ten feet of stra' a occur frcm the top of the 

 Bembridge Limestone to the top of the Great Lime tone (Upper 

 Lleadon). The Brockenhurst series does not exist here. Not 

 a single marine fo.-sil occurs in that interval. Nor is there any 

 bed having the least re-emblance either lithologically or pa'x- 

 ontologically to the Colwell Bay Venus bed. 



The Upper Headon at Headon Hill measures 50 feet and con- 

 tains the thick Lymnxan limestone (27 feet). The united or 

 combined thickness of the Osborne and Upper Headon beds 

 (Ge 'logical Survey) is 119 feet, i.e. adopting the top of the 

 Cerithium ventricosum bed as the boundary. The Osborne beds 

 at Headon Hill are below the Bembridge limestone and extend 

 up to it. SO there is no room. 



The Mia'd e Headon. — The uppermost and lower portions of 

 the Middle Headon are brackish-water beds abounding in 

 Cerithium ventricosum, C. pseudocincfum, C. concavutn, Ntritina 

 concava, and Nematuroe. The beds or series in Headon Hill 

 richest in Cytherea incrassata (Venus bed proper), exhibit identi- 

 cally the 'arae fossils as at Colwell Bay. 



Below the oyster band in grey sandy clays is the Venus bed, 

 extremely rich in marine fossils. Cytherea, Mya, Mactra, 

 Corbieula, Nucula, Irigonocalia, Fusus, Canccllaria, Voluta, 

 Viearra, und Natica ; Mya angustata and Cytherea incrassata 

 scattered throughout and abundant. The Middle Headon of 

 Headon Hill is 32 feet thick. The Survey vertical section gives 

 35 feet for the same boundaries. The height of the Middle 

 Headon above the sea level at the north-east end is 72 feet, and 

 not below the sea level, as seems required on Professor Judd's 

 theory. 



Lower Hcad.ni. — The first bed is a Lymnrca limestone, and is 

 the same well-known bed which forms the top of the Lower 

 Headon in Warden Cliff. It is traceable to How Ledge, where 

 it disappears below the sea, and clearly shows by its course that 

 it is the How Ledge bed of Warden Cliff. Although this lime- 

 stone is denuded from the top of the anticlinal curve between 

 West >n and Widdkk Chines, some of the 1 >wer beds are 

 traceable the whole distance; accordingly we can join on the 

 section in Headon Cliff to that in Warden Cliff. This gives a 

 continuous section and series of beds from the lowest seen of 

 the Lower- Headon, through the Middle and Upper Headon of 

 Colwel Bay to the Bembridge limestone both north and south. 

 There is therefore only one marine (Middle Hadon) series lying 

 between two fre hwater series, or "the Lower and Upper 

 Headon." The Rev. O. Fisher has discovered the Venus bed 

 in the Totland Bay brickyard, some slrrt distance above and 



