August 31, [882] 



NA TURE 



427 



Mr. Gardner places these Bournemouth beds in the Middle 

 Bagshots, drawing the line between these and the Lower 

 Bagshots at the pipe-clay beds of Corfe, Studland, and Alum 

 Bay in the Isle of Wight. This line of division is drawn on 

 account of the great dissimilarity of the flora contained in each. 

 The Bournemouth flora, which is distinct from the older, or 

 Alum Bay series, passes up into the so-called Oligocene without 

 any perceptible change or break ; but few, or none of the same 

 species pass down or occur with the Alum Bay beds. 



These Middle Bagshots are represented in Alum Bay by the 

 unfossiliferous beds marked 19 to 24 in Professor Prest- 

 wich's section, (Quarterly Journal of the Geological Society, 

 vol. x. p. 56,) and are 240 feet thick. Palasontologically, 

 these beds may be correlated with the continental Eocene, pro- 

 bably those of Aix-la-Chapelle. The cliffs fronting the sea 

 may be divided into three groups. The first extends from 

 Poole Harbour to Bateman's Chine, the second group extends 

 from the Sugar-loaf Chine to Watering Chine, the third section 

 or group extends from Watering Chine to the Bourne Valley.' 

 The chief interest attached to the Bournemouth beds is the 

 flora distributed chiefly through the Lower or Freshwater Series. 

 None of the prevailing Alum Bay types are found at Bourne- 

 mouth, nor are any of the well known Bouremouth types found 

 at Alum Bay, and according to Mr. Gardner, their affinities are 

 completely with the floras ascribed in France to the Oligocene, 

 and the forms of flora as at present known, chiefly Australian 

 and tropical American. 



The author has endeavoured to show that "a great river 

 existed throughout the whole of Eocene times, bringing deposits 

 from the westward, and that the Bournemouth cliffs present a 

 section across its bed, these deposits being formed during a con- 

 tinued period of sub-idence." The sudden change observed in 

 the beds from fine to coarse sediment, and the thickness of the 

 deposit, cannot be explained by the floods and fre hets inci- 

 dental to changing season 1 -, but are such as would occur whenever 

 subsidence exceeded, in however trifling a decree, the silting — 

 up power of the river," he. cit. p. 13. 



It is a question of impor ance whether the continental fbras 

 similar to our own at Bournemouth have been correctly deter- 

 mined. " For while all the strata that have yielded dicotyledo- 

 nous leaves or fruits below our Headen series are admitted to be 

 Eocene, scarcely any of the beds on the Continent resembling 

 them are ascribed to that age," but to the Miocene. " For as 

 all Eocene floras approximate more or less to Miocene, it has 

 been a kind of rule in the absence of strati graphical evidence, to 

 assume that all isolated patches with dicotyledons, belonged to 

 the latter period, and had the stratigraphies! evidence at Bjurne- 

 mouth been inconclusive, the whole of that Eocene formation 

 must also upon plant evidence (for we have no other) have been 

 classed as Miocene. 



The Lower Freshwater series are seen in the neighbourhood 

 of Corfe and some parts of the cliffs at Studland. It is 

 characterised by abundance of pipe-clays, and is about 2CO 

 feet thick. 



The MiMlc Freshwater seriis also occurs at Cofe and Stud- 

 land, and form the whole thickness of the cliff"-, between 

 Poole Harbour and Bournemouth, thus constituting a fine 

 section, 4 miles long and 100 feet in height, 



The next series is marine, and about 400 to 500 feet thick. 

 This marine group occupies the cliff- between Biscombe and 

 High Cliff. 



The Bournemouth flora appears to consist principally of 

 trees or hardwood shrubs, few remains of herbaceous plants 

 being preserved. The ferns are rare in the lower part of 

 the series, but become more abundant, almost to the exclu- 

 sion of other vegetation, towards the close of the middle 

 period. 



The prevailing group appears to be that of Acrostichum, 

 of which there were many species. Angiopteris, Nepro- 

 dium, GUichenia, and Lygodium, and other undescribed forms 

 occur. 



Among the Conifera; Cupressus, Taxodium, and Dacri- 

 dium, with indications of pinus. The Cycada: seem to have 

 di-appeared. 



The monocotyledons are well represented by reeds and rashes. 

 Nipadiles, represents the screw pines. The pal s are very 

 abundant, especially in the lowermost beds of Corfe and Stud- 

 land and the upper middle beds of Bournemouth ; many 



1 For particulars of ihese three groups, 

 Geological Society, xxxviii. pp. 5-8. 



Quarterly Journal of the 



Flabellaria, Sabal, and Flntnicites, occur ; the Smilaceas 

 occur in all the fossiliferous beds, and are represented by five 

 or six species. 



The Apetalce, illustrated by Fopulus, Ulmus, Laurus, 

 Quercus, Artocarpidium , and Daphnogena, with Carpinus, 

 Fagus, Castanca, Salix, and Fiats, and numeruus Proteaceae. 



Elaodendron, Rhamnus, Prunus, Juglans, Cluytia, Cerato- 

 petalum, with Dodonaa, Celastrus, Eucalyptus, and many 

 Leguminosa; illustrate and characterise the Polypetalce. 



Cactus and Stenocarpus are added for the first time to the 

 Eocene dicotyledons. 



Mr. Gardner believes that we have probably represented 

 almost every genus descended from Continental floras. 



The Eocene flora presents us with types peculiar to the 

 Southern Hemisphere, and related to those of Australia and the 

 adjacent islands. We have examples of this southern flora 

 through the Proteaceee, Leguminosa-, Conifers, and the Myrtacetr, 

 through Eucalyptus} 



Isle of Wight. 



The present rhomboidal form or configuration of the Isle of 

 Wight is due partly to the unequal acion of the sea on its coast 

 line, and partly to those disturbances or movements which have 

 thrown some of its strata into the positions exhibited at 

 Scratchell's Bay, Alum Bay, and Wbitecliff Bay. 



The rapid waste of the cliffs going on at Sandown and 

 Freshwater Bays is due to the action of the sea, the Lower 

 Greensand and Wealden strata there exposed being more easily 

 destroyed than the chalk. 



The leading physical feature in the structure of the Isle of 

 Wight consists in the ridge of high and bare chalk downs near 

 the centre of the island extending from the Needles ou the west 

 to Culver Cliff on the east. Another chalk range parallel to the 

 former, but on the south of the island, extends from St. 

 Catherine's Down on the west to Boniface Down on the east. 

 In the space occupied between these two chalk ranges or upper 

 cretaceous rocks, there occurs the complete succession of the 

 lower cretaceous a id lacustrine Wealden groups, comprising the 

 Hastings sand and Weald clay exposed at Compton Bay and 

 Rock Point on the west, and Sandown Bay on the eastern sile. 

 The central ridge is depressed and cut through by transverse 

 valleys ; such occur at Freshwater Gate, Shalcouibe, Calbourn, 

 and by the Carisbrook, Medina, and Brading valleys. "All 

 these breaks may possibly be on lines of faults running or 

 cutting through at right angles to the strike of the chalk." 



The part of the 1-le of Wight which lies to the north of the 

 central chalk range is entirely composed of the older Tertiary or 

 Eocene strata. The only fault of magnitude known in the 

 island is that occurring along the line of the Medina valley. 

 Those on the eastern side of the river are the Headon, Osborne, 

 and St. Helen's series. The rocks at West Cowe-, or west of 

 the Medini, belong to the Bern ridge marls or fhwio-marine 

 series. "From the known thickness of the several groups the 

 amount of displacement which takes place on the line of fault 

 between East and West Cowes, or along the line of the Medina, 

 cannot be le s than 200 feet." 



The longitudinal undulations affecting or disturbing the 

 Tertiary strata north of the chalk ridges are less obvious than 

 those above described. The chief flexures which are in imme- 

 diate sequence with the chalk are exhibited both at Whiieclift 

 and Alum Bays, where the Lower and Middle Tertiaries are 

 inclined at very high angles. 



The first set, or the east and west undulations, are connected 

 with the movement that elevated the chalk vertically. The north 

 and south undulations also affect the chalk, since each north and 

 souh valley formed by the synclinal curve or hollow of the roll, 

 corresponds to the division between the two chalk downs, and 

 each down to an anticlinal. All the Lower Tertiary strata, 

 including the fluvio-marine beds, are affected by these move- 

 ments. 



The gravel beds, which rest upon the older Tertiary strata, 

 whether the oldest or higher level gravels, or the newer, such as 

 those which occupy the combes and transverse va'leys, are un- 

 affected by these movements, showing that their origin is subse- 

 quent to the disturbing forces which affected the Secondary and 

 Tertiary rocks below them or on which they rest. 



1 Mr. Gardner has been greatly aided in his floral researches by Constantin 

 Baron Ettingshausen. Ph.D.. who has brought to bear his great knowledge 

 of fossil plant* and their discributijn through the higher Tertiaries. The 

 join, monograph by Mr. Gardner and Ettingshausen on the " British 

 Eocene Flora," in the Palaeontographical Society's volumes for 1879 are 

 oft u ehi hestvaltiel I students. 



