428 



NATURE 



| . Xugust 31, 1882 



1 ..u 1 1 Tii' 1 1 M-, s 1 1- a 1 1 of 1 in 1 11 1 or Wight. 

 11 ' Lower and Middle Eocene strata of the bit of Wight, 



up i" the i' im "i the fluvlo mi i lei [1 



better ntud'ed in the cliffs in Alum Bay and Whitei liff liay lhan 

 in 'i I'.n 1 "i the i'.l.iuil. 

 In these remarkable sections the whole of the strata, from the 



■ 1 1 hi to the fluvl .n mi formation are displayed in unbroken 



i hi 



Plastic Clay. 

 " 1 he lowe 1 mi mbei of thi ata in 1 lie Isle of 



Wight i the Plaslii Clay, or Woolwich and Reading erii ol 



Mi in m icb. " 1 he le bed an be it 1 -.. ed in Whiteclifl 



11. 11 'I Alum Bay, 1 specially the former, where the mottled 



■ 11 expo led. No foi sil have 01 1 111 red In the pi 1 tic 

 olay ol the island, Seven bed have been recognised, the whole 

 met urine 85 feel ; they constitutes narrow belt striking across 

 ; he 1 .1.111.1. 1 . i in" .in 1 he chalk, 



eds the plasl ii laj ad also f 1 1 a 



[I 1 .1. ii.iin • ai osa the 1 iland from the wt 

 Alain Bay to the east al Whitecliff 01 Culver Cliff; its thickness 

 is .ii.. .in .'on feet, A band of flint pebbles only 2 inches thick 

 divides the plastic clay from thi esenting the 



basemen! bed ol Mr, Prestwich. Nowhere in Britain can the 

 London cU) be so advantageously studied as al Whiteclifl Bay, 

 or where the characteristic fossils are better exposed. Twenty- 

 five to thirty characteristic species may be collected hen 

 Amongst others may be named Pinna affinis, Pectunculus 



media, and 

 ...... Tin snnelida Ditrupa plana b 



to the I ,ondon clay. 



MihiH e Eocene, 

 / Btds, 

 11 1. in iNyi, first applied the term Bsgshol 1 - the 

 . ii ,1 rii ol 1 ■ ' 1 1 ' 1 • \ lum 1 la) ind Whitei lift Bar, dividing 

 it Into upper, middle, a id lower, thu is. tl with the 



in ■ ei ie in the 1 ,ondon ares w hicb had been 

 previou Ij e il ibli hed by Mr, Pre 1 w it b, 



The Lower Bagshot beds a tlj developed in the isle of 



.ii"" 1 thii 1 n in Alum Bay ol 660 feet, the .1 



important Gen ndron, Taxites, Quercus, Juglans, 



Daphnogene, 1 ts, I aesalpina, Cassia, Ficus, 1 > i v Ira, 



Rhamnns and Sabal, &c, They compi ol variously- 



coloured uufossiliferous amis and clays, with ace impanying iron 

 sand lour and clay. 1 hese In 1 bed are in one place crowded 

 with the leaves of sub-tropical land plants illustrating no less than 



li) lamlli. 



Casuarinacfa, Celastracta; Com/era, Contacted, CuHoniacac, 

 Cupuli/erm, Cycadee, Bienicea, Euphorbiacea, Juglamlct, 



I ,in':n.;i; I. -.-I win ■.,..■, Maria, Pal ma, Proteacea, Rhamneit, 



nl ' ! same strata al Bournemouth 



ami ('..ii.- 1 astle in Dot el bin exhibit id identical bui also 



flora, 1 'in "i tin 1 i >und at Bournemouth 



. hes "i Mi. [, Gardner, 61 teen or sixteen 



tpecies occur in the pipe-cla] ol Alum Bay. As .1 whole liiey 



indicate a rathei high temperature. The Ron of the Lower 



bed . well known in Central Europe, has some affinities 



with thai .il our Hampshire basin. 



The tropical or sub-tropical character of the London claj 

 plants w .1 long ago worked out by Dr. Bowerbank, but ii was 

 reserved for Dr. De la Harpe to carry his comparison into the 

 Middle Eocene bed , and to show that th only a 



moderate decrease ol temperature, solar as plants could show, 

 in Hi, ..ii.. the deposition 01 thi Ba 



Braoklesham sands. The m period I ully 



out this conclusion, there being no essential difl 

 between the fossils of the London clay and th ise ol the Ba 

 or even the Barton beds, which would indj ate a marked change 



Ol .Innate. 



The flora of the Alum pecially distinguished by 



the number and variety ol its Leguminosse, The plant contents 



Lowet Bagshol beds ol Alum Bay approximate to that ol 



the I I Tun 1 "i till- family, 



fortj ' hi lined by Mr. Bowerbank. 



The junction between the London clay and the Lower Bagshot 

 Is clearly seen in Whitecliff Hay. The brown ferruginous claj 

 representing the former, and the lattei bj pale grey or white 

 sun, is a 1 null i"u-. 1 thick, in the 640 feel or these Lowe 



\luni Bay 11. other tossils are known Asm plants, 

 and <i<W/ 00 sf ttirs occur. 



Middle Baoshot Series, 

 Braekltsham Beds . 



Th 'ii' npri ed between the sands al the base of Head in 



Hill, and the pipe-clay bearing sand ane>clays(] ,ower Bagshots), 



overlying the London clay, at e subdi, tded 1 Bar on clay and 



Brackli linn beds, The Bracklenham beds in Alum liay are 

 represented by clays and marls in the lower port, and by while, 

 yellow, and crimson sands above. The 1 iwer beds are remark* 

 able for the quantity ol lignites, coaly or vegetable natter con 

 1, mini in ih. in, constituting beds from IS inches to 2 feet in 

 thickness. The black and coal-like appearance ol four ol these 

 bed are conspicuous and marked object* in the cliff, and deter- 

 the position of the Brack le ham scries. 



ih, uppermost beds of the series, or the yellow, white, and 

 crimson sands, are totally devoid of organic remains, 01 are un- 

 fa Mil, -ions. AtWbitectifl Bay the lowet part of the Bracklesha.ni 

 bed are green, clayey sands, containing Vcnericardiaplanicosta, 

 Turritilla intbricataria, NummulUes lavigatus. Six cones ol 

 fos il ■ are there recognised. A haul bed ol • 



composed of n led flinl pebbles in a ferruginous cement is also 



a marked feature in the cliffs al Alum Bay, defining the division 

 between the Brack lesham and overlying Barton clay. 



Barton Clay, 



The Barton serie . compo ed ol sandy clays and sand with 



ol .-pi iria, is sufficiently shown in Alum Bay, where il 

 iliiii 1 , ,1 llinl neSI Ol 300 feet, and is rich in fossil remains, the 



whole of which are marine, 48 genera 1 and 90 species of 

 molluscs alone have occured al Alum Bay. 



At Barton Cliff, on the mainland, or oppo ite coast of Hamp- 

 shin . a rich and abundant marine Iluscan fauna occurs. The 



lower beds al Alum liay contain Voluta luctatrix, Kimella, 

 (Rosttllaria) rimosa, Cenus or Conorbit dormitor, and Fuim 

 Ion ttvus, with CrassateUa sulcata, &c. 



II rri.n BAOSHOT Sands. 



The' e are the unfos iliferous sands below the Lower He 

 beds, 11 led extensively for glass-making, which may he 150 feet 

 thick at Alum Bay. In Whiteclifl Bay the junction between the 

 Uppei Bag hit sands and the Barton clay is sharp and well 



defined ; a few ca its ol fo ails occur hen-, but are in so friable a 



Btate thai they c 1 be removed. 



Examination ol the cliffs al Alum Bay will at once show that 

 the [strata from the chalk to the Upper Bagshots are highly 

 inclined, caused by the force that produced the anticlinal axis 

 winch traverses the i land east and west, and this axis brings to 

 the surface the Wealden beds in Brixton and Sandown Bay , 

 thus revealing the extent and continuity of the Wealden series, 

 and determining its presence westward to the Isle of Purb'ck 

 along the same east and wesl lineol elevati in. Eastward of the 

 Kle ol Wighl this axis is lost uinh 1 (In ,1 iters of the English 

 Channel, and we have no visible proof ol its influence towards 



Beachy lie d ; it may have aided in preparing a weakened line 

 for the cour e of the Channel towards the straits of Dover. 

 Ih,- ,' beds at llorwell Cliff have been the subject of a notice 

 by Mr. Tawney in the " Proceedings of the Cambridge Pbilo 

 sophic.il Society," and will be. referred to in the latter part of 

 my address. 



Fluvio-marine Series, 



ih.' t'.h -.ii Wight, the Btmbritlgi 

 serie, is by far the most constant in litAological characiei • I M 

 lower part, calcareous (marine and freshwater.) The upper part 

 (largest) consist of alternations of marls and 1 iminated clays. 



, 1 irger p irtion ofihe Tertiary surface of the Isle of 

 Wight is occupied by the Bembridge series, which overlie the 

 ffeadon beds, or Headon Hill group. Stratigraphically, or in a 

 scientific pmnt of view, ih.v possess high interest, being re- 

 ives of extensive continental formations, throug 

 n,- ire enabled to correlate or throw considerable light on the 

 classification of foreign Tertiary strata. 



Through these Bembridge strata we are also made acquainted 

 with nid acquire much information respecting the terrestrial 

 fauna ol our own area during the later portion of the Eocene 

 epoch, 



palseontologic illy the Upper Bembt idge mat la are characterised 



by the abundance of Me/unia turritissima These marls are 



fmely shown in Whitecliff Bay, on the shore at Hempstead, and 

 at Thorness, containing Cyrena pulchra. 



The upper beds 01 the second group are exposed in the 

 clearest manner through fine sections at the same places, and 



