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Ordinary meeting, Monday, July 6th, 1863
334
Third. The fresh-water stratum of that hard, rocky, compact clay in which we find t he Palu dinee. Fourth. A marine formation- t he London clay-which mostly lies upon a shell-rock and pebbles (commonly called the oyster-shell rock), which is its basement-bed. Fifth. We have several changes which are not chronicled here, or, if they have been, have shared the fate of part of the London clay, and have been denuded by that last agent, th e iceberg. W e can thus eas ily t race six g reat mutations w hich have occurred since th e deposition of th e Thanet sands, which we find capping the Chalk at Lewisham and Charlton. And when we thi nk t hat t he only traces of th ese changes are a few feet of strata, we cannot help feeling-even if we allow a greater intensity of action in t he earlier period of the deposition of the stratified rocks-how vast an amount of time mnst have elapsed since water first played its par t in t he construction of our globe. Ordinary Meeting, Monday, J uly 6th, 1863.
Professor Tennant, F.G.S., P resident, in the Chair. 'l'he following gentleman was elected a member of the Association :-William Lest er, Esq. The following specimens were exhibite d from Cariboo, Briti sh Columbia, by Professor Tennant, the propert y of t he Bishop of Columbia, who had collec ted th em August, 1862 :- GOLD from Willi am's Creek, Light ning Creek, and Lowhee Creek. ROCKSCellular lava, quartz rock, clay slat e, chlorit e slate . MINERALSIron pyrites, carb onat e of iron, galena, &0. The following papers were th en read : 1st. "A Report of the Visit to the Dudley Geological Society's Anniversary Meeting, by the President and oth er members of this Association, held at Dudley, May 27-28, 1863." By Christl" Th os. Richardson, M.D., Cantab. Th e report contained a general description of the prominent features of geolog ical interest in t he neighb ourhood of Dudley, and
335 described the several advantages and opportunities it afforded for study, to both th e early and advanced st udent, of several of th e great and characteristic phenomena recogni sed as causes, effects, and agenci es by geological science. Th e proceedin gs of the meeting were bri efly detailed, consisting chiefly of th e delivery of th e annual address by S. H. Blackwell F.G. S., in which a most able and comprehensive review was entered upon of th e progr ess of geolog ical science within th e last 20 yea rs . particularly with reference t o t he changes in nomenclature and classification, phys ical an d practical geology and paleeontology , and the recent evidence per tain ing t o th e history of th e antiquity of man. A short addr ess was also given by Profe ssor Tennant, F.G.S., on "The Connection and Relation of Mineralogy and Geology." Visit s were likewi se made to some points of interest in t he neighbourhood, at which full descriptions were given of th eir charac teristic features by some of t he local geologi sts conversa nt with them. Th e two chief localiti es were th ose know n as th e Castle and Wren' s Nest Hill s, eminences of about 700 feet in height, constituted by t he upheaval and protrus ion of the Ludlow and W enlock Limest ones of the Upper Silurian rocks, through th e local series of the coal-measures. These beds of limesto ne, separated by shales, ha ve been long worked, and extracted for economic purposes in th e man ufacture of iron, leaving behind most ex tensive and curious cav erns , pres enting many highly instructiv e illustrations of important geological events . By permission, th e members of th e Associati on were witn esses of the interestin g process of smelting and casting iron on a large scale into its first mark etable form of pigs from t he rough ore, and th e combustion of iron in atmospheric air, both of which processes were, with all connected with th em, most ably detailed by th e proprietor. A visit wa s also made to a neigh bouring coal-pit, int o which a large party descended. Th e seam being worked was th at known locally as th e Thick Coal or Ten- yard Seam, where a full detail was kindly g iven by one of th e ge ntlemen associated in th e work, upon all the points of interest; and in th e progr ess through the mine
336 attention was called to the extent, limit s, and variations of t he several beds composing t he great seam ; it s crac ks, fissures, faults, and subsidences ; th e pervasion and int rusion of veins and masses of bas alt and gr eenstone, and th eir metamorphosing action upon th e coal in contact with th em; the mode of working th e coal visibly illustrated; and the dan gers ari sing from, and the situations in which the two noxious gases choke- and fire-damp become ge nerated, and t he inflammable nature of th e latter shown by t he ign ition and explosion of a quan tity purpose ly allowed to accumulate. The aut hor concluded by men tioning' the kind recepti on and welcome given to th e deputation by th e Dudley Society, the gratification the visit had afforded them; and th e hope of a rep etition of the visit and th e establishment of a close and intimat e connection between the two societies established. 2nd. "On th e Geological Distribution of t he ' P it harella Rickmani.' '' By Mr. C. Ev ans. In this paper Mr. Evans, 'after noticin&" th e discovery of the first spe cimen of Pitharella, by Mr. Edmund Jones, in Cow Lane, P eckham , observed th at during the construction of the Efra branch of th e Southern Hi gh Level Sewer, near St. Mary 's Church, P eckham, numerous specimens of t his shell were found in the P aludina-band (described by Mr, Rickman in No.6 of our Proceedings), chiefly in th e form of casts. At the t unnel at Dulwich, on the same line of sewer, blocks of sandstone abounding with foss ils were exposed . On a few well preserved specimens of th e Pitharella being met with in the latter stone, Mr. F. E. Edwards published a descripti on with figures of the shell in t he Geologist for J une, 1860, and th en assigned to it the above ge neric and specific names. I t was considered by th at ge nt leman t o be allied to the Auriculidss, Achatinidee, or Limnseidee, At th e meeti ng of this Ass ociation, held on the 4th March, 1861, Mr. Pickering questi oned the correct ness of Mr. Edwards' s conclusion, and expresse d his opinion th at th e P itharella was more closely allied to Ampullaria, P aludin a, Melania, and P alud omus. .As these latter shells belong to t he g reat group of Operculated Mollusca, Mr, Evans submitted to 1\11'. Pickering , and afterwards direc ted attention ill th e Geologist for June, 1861, to a single
337 specimen of an elongated operculum, which he had obtained from the P aludina-band at Peckham, which appeared to him to be fitted rather for th e elongated aperture of Pitharella t han to th e rounded mouth of th e P aludinrs. Mr. Bott also, dwelling more particularly on t he vary ing proporti ons of th e spire, has suggested t hat t he specimens met with in t he P aludina-band should possibly be grouped as t wo disti nct species. F or th e corre ct determination of the various questions which have been from time to time raised on th is subj ect, it is desirable that due considerati on should be given to the mineral characters of the be ds in which th e shells occur, and to the fossils with which th ey ar e usually associat ed. The P eckham Palud ina- band may be described as an indurated marl or calcareous clay, and was probably deposited as fine silt at t he bot tom of a st ream or pond. It was a purely freshwater deposit, as specimens of P aludina may be observed scattered sparingly thro ughout . At occasional intervals vast numbers of th ese shells were spread over the surface, after which th e former condition of a muddy deposition appea rs to have recurred. It is in th ese bands th at numerous specimens of P itharella have been met with, and when so preserved th e spires of the different specimens are found to vary greatly as to th e amount of eleva tion. In th is sa me bed have been fonnd a Unio, num erous opercula re sembling t hat of Paludina, a more elongated form of operculum noticed above, also scales and a few teeth of Fishes, Chelonian remains, and, rarely, leaves, and the ely tra of Coleopte ra . Th e same band was again well seen in t he open cutting at East Dulwich, which was commenced after t he t unne l was completed. Fr om thi s spot numerous specimens of th e Palud ina were obtained, and a few casts of Pitharella, resembling in form those from Peckham. This band was associ ated with, but dis tinct from, beds abounding with Cyrena , t ogeth er with a layer of oystcr-sbells, and it occupied the same relativ e position in the sect ion as t he Paludin aband at P eckham. Below was a deposit of woody clays and greenish san ds, and ncar th e bottom of th e excavation large masses of th e hard shelly san dsto ne or " Dulwich Rock," were met wit h.
338 There appeared to be two varieties of this latter stone, differing somewhat the one from the other in mineral character and fossil contents, although both varieties were occasionally met with in the same block. The most common of these two varieties may be described as consisting of a crystalline sandstone, containing patches or small nodules of a brown, green, or red earthy material, occasionally indurated, and abounding with several species of Cyrena (including C. Dulwichiensis), mostly as single valves, but occasionally with the valves united and closed; with these the scales of a ganoid fish (Lepidotus or Lepidosteus) were present in considerable numbers, with occasionally wood, bone of the Trionyx or River-tortoise and Mammalian bones and teeth. The other variety, consisting also of crystalline sandstone, contained fewer Cyrenre, although they are still the most abundant fossils, and in addition to these Mr. Evans found fine double specimens of Cyrena Dulwichiensis, together with Melania inquinata, Cerithium funatum, Melanopsis buccinoides, Noritina globulus, N. consobrina, Rissoa or Hydrobia, Unio, Ostrea, &c. Many samples of this variety contain masses of wood of considerable size, often bored by fine specimens of Teredo and Teredina. Few Pitharellas were to be found in the first of the above varieties, the most favourable lumps being those that contained fewer Cyrenee and much wood. In one small block which contained a large mass of wood with Teredo, were found as many as 22 specimens of the Pitharella, mostly of small size and with thin shells. Mr. Evans then endeavoured, from a consideration of the habits of the recent analogues of the most abundant fossils, to arrive at some conclusion as to the condition under which these various deposits were formed, and suggested, without forming any very decided opinion, that these beds were fitted rather to serve as the habitat of a shell allied to the Ampullaridee than to the more purely freshwater family of Limnteidee. He also suggested, in conclusion, that a change of character of the river-bed, or a slight change of climate might have given rise to variations in the general proportions of the shell:1I<
* On
the occasion when the above paper was read, Mr. Bott exhibited some
339 3rd. "Observations on Ammonites, and on the Natural History of the Tribe of Molluscous Animals to which these remarkable extinct shells are supposed to belong." By E. Charlesworth, F.G.S. The following account of the visit of the Association to Herne Bay and Reculver, has been prepared by Mr. George Dowker, who directed the excursion : About 30 of the members assembled at Herne Bay on June 26th, 1863, and proceeded in conveyances to Reculver, passing on their way the various sections exhibited near the bridge-crossings of the Herne Bay and Margate Railway (now in course of construction). The first of these sections (a short distance from the Bay) shows, in a deep cutting, the London clay, capped by an ochreous clay and gravel. The next crossing, near May-street, towards Hillborough, exhibits a section in the pebbly gravel-beds similar to those capping the cliffs near Bishopstone, it being probable that the flint implements found near Reculver belong to this deposit. It is a point of considerable interest to determine its probable geological date. If I might venture a conclusion on this most difficult subject, I should place these deposits in the third subaerial epoch of the glacial period of Professor King's 'I'able.t These deposits are supposed to be of fresh-water origin, the river-beds of tributaries of the Thames, before the sea encroached on its present domain. On alighting at Reculver we proceeded to view the church and Roman Castrum. Reculver, the ancient Regulbium, was a military station of great importance in the time of the Romans. Reculver and Richborough were the Roman stations constituting the Rutupire, and were then at the entrance to the estuary, which reached from Reculver to Pegwell Bay, constituting the western boundary of the Isle of Thanet. I believe the Geologists' Association could not have chosen a spot containing more instruction in a geological and historical point of view. It is here that archeeology and geology meet, stationed in this Roman Castrum, whose timeworn walls are crumbling to fossils from the Dnlwich rock, comprising, in addition to some fine Pithareilas, a specimen of Bulimus ellipticus, and Mammalian remains. t See Geologist for M:ay, 1863.
340
decay. Beneath th ese old church-t owers, th e emblems of a state and power now passed away, without a record of the past, save the rud e architect ure of th e Roman or early Saxon," the burial-place of kin gs, whose whitened bones protruding fr om t he cliff mark how the clamorous waves hav e violat ed the sacred precincts of th e dead. H ere, too, we tread upon a soil once held by races of pre-historic man, whose TIlde flint implements are found upon th e shore. The migh ty deep is g aining on th e land, and acting over again her a ncient part in forming fresh deposits from the wrecked debris of former ages. Leland speaks of Reculver in his time as " sore decayed, and distant half a mile from the sea." In 1780 th e north wall of th e Roman Oastrum, whi ch was dist ant 80 yards from the church, bad been lat ely overthrown by the sea, and th e ang le of the t ower to th e north was distant 50 yards from th e borde r of th e precipice. At the present time (1863) th e tower to th e nor th is close to th e edge of th e cliff, which is preserved by num erous g roins erec ted by th e Tri nity H ouse. It wa s shown by Mr. Masters t hat numerous semi-fossil t ru nks of t rees had been found in the neigh bouring marshes, and were, in some cases , larg e enough to be use d for building- purposes. Reculver was chosen by Kin g Eth elbert as his place of resid ence, and he was' buried th ere about th e ye ar 616. Section in Chalk-pit North
if Okisiet.
About 4 ft.
b. Brick-earth.
Abou t 3ft.
c. Green-coloured sand, with small fragments of thin flints, wit h a bed of large greencoated Hint s.
---",_ _
~ l
d. Ferruginous
-r__ .--l
dark clay, filling sand -pipe.
I
--'~
* Ri chborough, Reculver, an d Lym e.
_'__ _
e. Chalk.
G. Roach Smith.
341 From this elevated point of view the chalk-cliff of Birchington can be seen. The chalk again rises near Chislet, where a section to be seen in a chalk-pit on the right hand side of the road north of the church presents features of much interest, which will be best understood from the accompanying sketch. If c in the figure be true bedded Thanet sand, with the usual flints at the base, it seems difficult to account for the yellow clay filling the pipe beneath, unless we suppose it to have some connection with the upper beds not here shown. On the other side of the road a section of drift over the chalk is seen, which has been described by Mr. Prestwich in the Geological Journal, No. 42, page 111. The chalk of Birchington has not those regular layers of stratified flints so often seen in the upper chalk; thin tabular flints often occur in a diagonal, or nearly vertical, position at places. The chalk appears much denuded and broken up, the surface being strewn with green coated flints, derived from the base of the Thanet sands. On the other hand, the chalk of Ramsgate and Pegwell presents the well known beds of flints every three or four feet apart. Richborough Castle, almost to be seen from this point, is situated upon a portion of the Woolwich beds, having the Thanet sands at its base. Descending from the churchyard at Reculver we find the cliff composed almost entirely of that portion of the Lower London Tertiaries, called by Mr. Prestwich" the Thanet Sands," composed essentially of a yellow and greenish quartzose saud, becoming more argillaceous as we descend; and having interspersed at its upper part (here at the base of the cliff) tabular concretionary blocks of indurated sandstone, these blocks generally resting upon a very fossiliferous deposit, and often with shells of the genus Cyprina, in great abundance. The shells of this deposit are very friable, owing to the porous nature of the sands they are embedded in, and are, in many places, found chiefly as casts. These Thanet sands extend downwards to the depth of 90 to 100 feet, as I have proved in a well sunk at Stourmouth.'"
*
See Geologist, 1861, P: 213.
342
Mr. Prestwich, to whom every gcologist must be deeply indebt ed for his knowl edge of the lower tert iaries, has so ably descrih ed the sections exhibited here th at I cannot do bet ter than quote his ge nera l conclusions on these interestin g format ions :-" The Thanet san ds are the lowest of th e eocene strata of England, and Mr. Prest wich has shown t heir connection w ith the Lower Landenian beds of Belgium, describe d hy Sir Charles Lyell. Th e latter are characterized by a g ree n sanrl and sandstone, t ermed glauconite. Th e connecting link between t he cret aceous and tertiary strata is w ant ing in England, an d is represented on th e cont inent by the Meestri ch beds. 'I'he chalk appears to have been ext ensively denud ed previous to t he deposition of t he lower eocene beds." P assing along t he cliff, towards He rne Bay , we find this Qed (the Thanet sands) gradually dip, until at Bishopstone it is lost in t he base of th e cliff. Immediat ely over th is deposit is anot her (here very similar in lith ological cha ra ct er where t he two meet). It is the middle of t he lower or eocene London tertiaries, termed t he W oolwich beds, from being largely developed at ,Voolwich, where they form st rat a. of considerable thi ckness, consistip g of clay, sand s, and pebble-beds. Near H erne Bay th e pebbles are, for the most part, wanting , the beds being composed almost enti rely of a quartzose ochreou s sand, at parts inclining t o ferruginous, and in the lower part much mixed with a green sand. Near W oolwich this series is distin guished by a mixture of marine and freshwat er shells. Among th e latter Cyrena cuneiformis is very common. H ere it assumes more of a marine characte r ; traced in a west erly direction from H erne Bay th is deposit assumes a more and more fresh wat er cha rac ter. Over thi s strat um we meet wit h anot her deposit , consisting of ligh tcoloured sands, with concretionary mass es of red san d, conta ining much iron, and at it s lower part thin pebble-beds. I am not quite sure if the thin pebble-bed between this and the Woolwich beds should belong t o the upper or lower series. This deposit is termed by Mr. Prestwich th e basement-bed of th e Lond on clay. Near Cante rbury parts of th ese beds have been quarried for smeltin g- purposes; and it is not uncommon to find " colliers " ballasting back to th e north with thi s iron.
343
Before reaching Bishopstone the London clay proper has made its appearance over this light-coloured basement-bed, with which it contrasts greatly in colour and appearance; and from this point the lower beds dip under towards Herne Bay, where the London clay forms the entire cliff. Owing to the great contrasts of colour and difference of the strata forming these cliffs, they present a most picturesque appearance. The lower sandy beds fall to the waves only from being undermined, and present a nearly perpendicular face, the concretionary masses of sandstone forming a pavement to the beach. The London clay, on the other hand, is constantly slipping down, and presents an irregular inclined plane. See Fig. 2. The London clay this side of Herne Bay is not very fossiliferous, but abounds in selenite. I have made little mention of the fossils to be found here, but the collector must possess much patience if he hopes to transport the shells from these beds to his cabinet. The Thanet Sands abound with fossils, but in these will be found few species-Cyprina Morrisii, being by far the most common in the whole series; Thracia oblata, Panopeea, Cytherea orbicularis. These are the most common. In the Woolwich beds Corbula, Dentalium, Cuculleea, and Cyprina being common. Large masses of silicified wood, often bored by Teredo, are found in this and the Tbanet Sands, some of which was procured from Reculver by the excursionists. In the Basementbed many fossils are found in casts in the concreted masses of iron-rust and pebbles. For a more detailed account of these deposits, I must refer my reader to the excellent .papers on the Thanet Sands and Woolwich beds by Mr. Prestwich, in the Geological Society's Journal. I will conclude this paper with a description of the drawings annexed, which, being not mere diagrams, but careful drawings taken on the spot, will give you a better idea of the appearance of these cliffs than any description, and will, I hope, guide the tourist in his search of the geological sections of this cliff. Fig. 1 represents the cliff about one mile west of Reculver, tho towers of which are seen in the distance. On the top of the cliff at a we have a drift-gravel, from which, most probably, the flint 2 F
344
implements found here have been derived. Beneath this, b represents the basement-bed, but little shown, however, but containing, beside pebbles, some tabular blocks of sandstone. Then, at c the Woolwich beds, composed here almost entirely of light-coloured sand, and forming the most part of the cliff. The junction of this bed with the Thanet Sands at d is very obscure; and, as a general rule in East Kent, I should say none but the practised eye could detect the difference. At the base of the cliff are seen large masses of argillaceous sand-blocks, exceeding rich in fossil shells; these belong to the Thanet Sands. They here resist the action of the waves better than the upper sand, which presents a perpendicular surface till undermined by the waves, when large masses fall, and the more sandy portions are speedily washed away. Quite at the base of the cliff are seen several sandstone blocks, derived from the Basement bed, b. Fig. 2 is a drawing of the sections shown at the Oldhaven Gap, looking towards Herne Bay. The top of the cliff is here composed of gravel-drift, marked a. The junction of this with the London clay is not seen in the Gap, probably from some drift and disturbance; but immediately beyond the dark London clay is distinctly seen capping the light sands of the Basement-bed, c. The London clay also extends considerably eastward of the Gap towards Reculver. The characteristics of the Basement-bed are here beautifully shown. The upper part of the section in the foreground is composed of this deposit. The light and almost pure sand is drifted by the wind, and at the corner leaves the ironstone blocks and concretionary masses in relief. The band of pebbles is likewise here distinctly marked, and forms the boundary-line between the Basement-bed and the Woolwich beds d, which latter compose the rest of the cliff.
Ordinary Meeting, Monday, November Brd, 1863.
Professor Tennant, F.G.S., President, in the Chair. The following donations were announced:" Smithsonian Report of 1861."
Third. The fresh-water stratum of that hard, rocky, compact clay in which we find t he Palu dinee. Fourth. A marine formation- t he London clay-which mostly lies upon a shell-rock and pebbles (commonly called the oyster-shell rock), which is its basement-bed. Fifth. We have several changes which are not chronicled here, or, if they have been, have shared the fate of part of the London clay, and have been denuded by that last agent, th e iceberg. W e can thus eas ily t race six g reat mutations w hich have occurred since th e deposition of th e Thanet sands, which we find capping the Chalk at Lewisham and Charlton. And when we thi nk t hat t he only traces of th ese changes are a few feet of strata, we cannot help feeling-even if we allow a greater intensity of action in t he earlier period of the deposition of the stratified rocks-how vast an amount of time mnst have elapsed since water first played its par t in t he construction of our globe. Ordinary Meeting, Monday, J uly 6th, 1863.
Professor Tennant, F.G.S., P resident, in the Chair. 'l'he following gentleman was elected a member of the Association :-William Lest er, Esq. The following specimens were exhibite d from Cariboo, Briti sh Columbia, by Professor Tennant, the propert y of t he Bishop of Columbia, who had collec ted th em August, 1862 :- GOLD from Willi am's Creek, Light ning Creek, and Lowhee Creek. ROCKSCellular lava, quartz rock, clay slat e, chlorit e slate . MINERALSIron pyrites, carb onat e of iron, galena, &0. The following papers were th en read : 1st. "A Report of the Visit to the Dudley Geological Society's Anniversary Meeting, by the President and oth er members of this Association, held at Dudley, May 27-28, 1863." By Christl" Th os. Richardson, M.D., Cantab. Th e report contained a general description of the prominent features of geolog ical interest in t he neighb ourhood of Dudley, and
335 described the several advantages and opportunities it afforded for study, to both th e early and advanced st udent, of several of th e great and characteristic phenomena recogni sed as causes, effects, and agenci es by geological science. Th e proceedin gs of the meeting were bri efly detailed, consisting chiefly of th e delivery of th e annual address by S. H. Blackwell F.G. S., in which a most able and comprehensive review was entered upon of th e progr ess of geolog ical science within th e last 20 yea rs . particularly with reference t o t he changes in nomenclature and classification, phys ical an d practical geology and paleeontology , and the recent evidence per tain ing t o th e history of th e antiquity of man. A short addr ess was also given by Profe ssor Tennant, F.G.S., on "The Connection and Relation of Mineralogy and Geology." Visit s were likewi se made to some points of interest in t he neighbourhood, at which full descriptions were given of th eir charac teristic features by some of t he local geologi sts conversa nt with them. Th e two chief localiti es were th ose know n as th e Castle and Wren' s Nest Hill s, eminences of about 700 feet in height, constituted by t he upheaval and protrus ion of the Ludlow and W enlock Limest ones of the Upper Silurian rocks, through th e local series of the coal-measures. These beds of limesto ne, separated by shales, ha ve been long worked, and extracted for economic purposes in th e man ufacture of iron, leaving behind most ex tensive and curious cav erns , pres enting many highly instructiv e illustrations of important geological events . By permission, th e members of th e Associati on were witn esses of the interestin g process of smelting and casting iron on a large scale into its first mark etable form of pigs from t he rough ore, and th e combustion of iron in atmospheric air, both of which processes were, with all connected with th em, most ably detailed by th e proprietor. A visit wa s also made to a neigh bouring coal-pit, int o which a large party descended. Th e seam being worked was th at known locally as th e Thick Coal or Ten- yard Seam, where a full detail was kindly g iven by one of th e ge ntlemen associated in th e work, upon all the points of interest; and in th e progr ess through the mine
336 attention was called to the extent, limit s, and variations of t he several beds composing t he great seam ; it s crac ks, fissures, faults, and subsidences ; th e pervasion and int rusion of veins and masses of bas alt and gr eenstone, and th eir metamorphosing action upon th e coal in contact with th em; the mode of working th e coal visibly illustrated; and the dan gers ari sing from, and the situations in which the two noxious gases choke- and fire-damp become ge nerated, and t he inflammable nature of th e latter shown by t he ign ition and explosion of a quan tity purpose ly allowed to accumulate. The aut hor concluded by men tioning' the kind recepti on and welcome given to th e deputation by th e Dudley Society, the gratification the visit had afforded them; and th e hope of a rep etition of the visit and th e establishment of a close and intimat e connection between the two societies established. 2nd. "On th e Geological Distribution of t he ' P it harella Rickmani.' '' By Mr. C. Ev ans. In this paper Mr. Evans, 'after noticin&" th e discovery of the first spe cimen of Pitharella, by Mr. Edmund Jones, in Cow Lane, P eckham , observed th at during the construction of the Efra branch of th e Southern Hi gh Level Sewer, near St. Mary 's Church, P eckham, numerous specimens of t his shell were found in the P aludina-band (described by Mr, Rickman in No.6 of our Proceedings), chiefly in th e form of casts. At the t unnel at Dulwich, on the same line of sewer, blocks of sandstone abounding with foss ils were exposed . On a few well preserved specimens of th e Pitharella being met with in the latter stone, Mr. F. E. Edwards published a descripti on with figures of the shell in t he Geologist for J une, 1860, and th en assigned to it the above ge neric and specific names. I t was considered by th at ge nt leman t o be allied to the Auriculidss, Achatinidee, or Limnseidee, At th e meeti ng of this Ass ociation, held on the 4th March, 1861, Mr. Pickering questi oned the correct ness of Mr. Edwards' s conclusion, and expresse d his opinion th at th e P itharella was more closely allied to Ampullaria, P aludin a, Melania, and P alud omus. .As these latter shells belong to t he g reat group of Operculated Mollusca, Mr, Evans submitted to 1\11'. Pickering , and afterwards direc ted attention ill th e Geologist for June, 1861, to a single
337 specimen of an elongated operculum, which he had obtained from the P aludina-band at Peckham, which appeared to him to be fitted rather for th e elongated aperture of Pitharella t han to th e rounded mouth of th e P aludinrs. Mr. Bott also, dwelling more particularly on t he vary ing proporti ons of th e spire, has suggested t hat t he specimens met with in t he P aludina-band should possibly be grouped as t wo disti nct species. F or th e corre ct determination of the various questions which have been from time to time raised on th is subj ect, it is desirable that due considerati on should be given to the mineral characters of the be ds in which th e shells occur, and to the fossils with which th ey ar e usually associat ed. The P eckham Palud ina- band may be described as an indurated marl or calcareous clay, and was probably deposited as fine silt at t he bot tom of a st ream or pond. It was a purely freshwater deposit, as specimens of P aludina may be observed scattered sparingly thro ughout . At occasional intervals vast numbers of th ese shells were spread over the surface, after which th e former condition of a muddy deposition appea rs to have recurred. It is in th ese bands th at numerous specimens of P itharella have been met with, and when so preserved th e spires of the different specimens are found to vary greatly as to th e amount of eleva tion. In th is sa me bed have been fonnd a Unio, num erous opercula re sembling t hat of Paludina, a more elongated form of operculum noticed above, also scales and a few teeth of Fishes, Chelonian remains, and, rarely, leaves, and the ely tra of Coleopte ra . Th e same band was again well seen in t he open cutting at East Dulwich, which was commenced after t he t unne l was completed. Fr om thi s spot numerous specimens of th e Palud ina were obtained, and a few casts of Pitharella, resembling in form those from Peckham. This band was associ ated with, but dis tinct from, beds abounding with Cyrena , t ogeth er with a layer of oystcr-sbells, and it occupied the same relativ e position in the sect ion as t he Paludin aband at P eckham. Below was a deposit of woody clays and greenish san ds, and ncar th e bottom of th e excavation large masses of th e hard shelly san dsto ne or " Dulwich Rock," were met wit h.
338 There appeared to be two varieties of this latter stone, differing somewhat the one from the other in mineral character and fossil contents, although both varieties were occasionally met with in the same block. The most common of these two varieties may be described as consisting of a crystalline sandstone, containing patches or small nodules of a brown, green, or red earthy material, occasionally indurated, and abounding with several species of Cyrena (including C. Dulwichiensis), mostly as single valves, but occasionally with the valves united and closed; with these the scales of a ganoid fish (Lepidotus or Lepidosteus) were present in considerable numbers, with occasionally wood, bone of the Trionyx or River-tortoise and Mammalian bones and teeth. The other variety, consisting also of crystalline sandstone, contained fewer Cyrenre, although they are still the most abundant fossils, and in addition to these Mr. Evans found fine double specimens of Cyrena Dulwichiensis, together with Melania inquinata, Cerithium funatum, Melanopsis buccinoides, Noritina globulus, N. consobrina, Rissoa or Hydrobia, Unio, Ostrea, &c. Many samples of this variety contain masses of wood of considerable size, often bored by fine specimens of Teredo and Teredina. Few Pitharellas were to be found in the first of the above varieties, the most favourable lumps being those that contained fewer Cyrenee and much wood. In one small block which contained a large mass of wood with Teredo, were found as many as 22 specimens of the Pitharella, mostly of small size and with thin shells. Mr. Evans then endeavoured, from a consideration of the habits of the recent analogues of the most abundant fossils, to arrive at some conclusion as to the condition under which these various deposits were formed, and suggested, without forming any very decided opinion, that these beds were fitted rather to serve as the habitat of a shell allied to the Ampullaridee than to the more purely freshwater family of Limnteidee. He also suggested, in conclusion, that a change of character of the river-bed, or a slight change of climate might have given rise to variations in the general proportions of the shell:1I<
* On
the occasion when the above paper was read, Mr. Bott exhibited some
339 3rd. "Observations on Ammonites, and on the Natural History of the Tribe of Molluscous Animals to which these remarkable extinct shells are supposed to belong." By E. Charlesworth, F.G.S. The following account of the visit of the Association to Herne Bay and Reculver, has been prepared by Mr. George Dowker, who directed the excursion : About 30 of the members assembled at Herne Bay on June 26th, 1863, and proceeded in conveyances to Reculver, passing on their way the various sections exhibited near the bridge-crossings of the Herne Bay and Margate Railway (now in course of construction). The first of these sections (a short distance from the Bay) shows, in a deep cutting, the London clay, capped by an ochreous clay and gravel. The next crossing, near May-street, towards Hillborough, exhibits a section in the pebbly gravel-beds similar to those capping the cliffs near Bishopstone, it being probable that the flint implements found near Reculver belong to this deposit. It is a point of considerable interest to determine its probable geological date. If I might venture a conclusion on this most difficult subject, I should place these deposits in the third subaerial epoch of the glacial period of Professor King's 'I'able.t These deposits are supposed to be of fresh-water origin, the river-beds of tributaries of the Thames, before the sea encroached on its present domain. On alighting at Reculver we proceeded to view the church and Roman Castrum. Reculver, the ancient Regulbium, was a military station of great importance in the time of the Romans. Reculver and Richborough were the Roman stations constituting the Rutupire, and were then at the entrance to the estuary, which reached from Reculver to Pegwell Bay, constituting the western boundary of the Isle of Thanet. I believe the Geologists' Association could not have chosen a spot containing more instruction in a geological and historical point of view. It is here that archeeology and geology meet, stationed in this Roman Castrum, whose timeworn walls are crumbling to fossils from the Dnlwich rock, comprising, in addition to some fine Pithareilas, a specimen of Bulimus ellipticus, and Mammalian remains. t See Geologist for M:ay, 1863.
340
decay. Beneath th ese old church-t owers, th e emblems of a state and power now passed away, without a record of the past, save the rud e architect ure of th e Roman or early Saxon," the burial-place of kin gs, whose whitened bones protruding fr om t he cliff mark how the clamorous waves hav e violat ed the sacred precincts of th e dead. H ere, too, we tread upon a soil once held by races of pre-historic man, whose TIlde flint implements are found upon th e shore. The migh ty deep is g aining on th e land, and acting over again her a ncient part in forming fresh deposits from the wrecked debris of former ages. Leland speaks of Reculver in his time as " sore decayed, and distant half a mile from the sea." In 1780 th e north wall of th e Roman Oastrum, whi ch was dist ant 80 yards from the church, bad been lat ely overthrown by the sea, and th e ang le of the t ower to th e north was distant 50 yards from th e borde r of th e precipice. At the present time (1863) th e tower to th e nor th is close to th e edge of th e cliff, which is preserved by num erous g roins erec ted by th e Tri nity H ouse. It wa s shown by Mr. Masters t hat numerous semi-fossil t ru nks of t rees had been found in the neigh bouring marshes, and were, in some cases , larg e enough to be use d for building- purposes. Reculver was chosen by Kin g Eth elbert as his place of resid ence, and he was' buried th ere about th e ye ar 616. Section in Chalk-pit North
if Okisiet.
About 4 ft.
b. Brick-earth.
Abou t 3ft.
c. Green-coloured sand, with small fragments of thin flints, wit h a bed of large greencoated Hint s.
---",_ _
~ l
d. Ferruginous
-r__ .--l
dark clay, filling sand -pipe.
I
--'~
* Ri chborough, Reculver, an d Lym e.
_'__ _
e. Chalk.
G. Roach Smith.
341 From this elevated point of view the chalk-cliff of Birchington can be seen. The chalk again rises near Chislet, where a section to be seen in a chalk-pit on the right hand side of the road north of the church presents features of much interest, which will be best understood from the accompanying sketch. If c in the figure be true bedded Thanet sand, with the usual flints at the base, it seems difficult to account for the yellow clay filling the pipe beneath, unless we suppose it to have some connection with the upper beds not here shown. On the other side of the road a section of drift over the chalk is seen, which has been described by Mr. Prestwich in the Geological Journal, No. 42, page 111. The chalk of Birchington has not those regular layers of stratified flints so often seen in the upper chalk; thin tabular flints often occur in a diagonal, or nearly vertical, position at places. The chalk appears much denuded and broken up, the surface being strewn with green coated flints, derived from the base of the Thanet sands. On the other hand, the chalk of Ramsgate and Pegwell presents the well known beds of flints every three or four feet apart. Richborough Castle, almost to be seen from this point, is situated upon a portion of the Woolwich beds, having the Thanet sands at its base. Descending from the churchyard at Reculver we find the cliff composed almost entirely of that portion of the Lower London Tertiaries, called by Mr. Prestwich" the Thanet Sands," composed essentially of a yellow and greenish quartzose saud, becoming more argillaceous as we descend; and having interspersed at its upper part (here at the base of the cliff) tabular concretionary blocks of indurated sandstone, these blocks generally resting upon a very fossiliferous deposit, and often with shells of the genus Cyprina, in great abundance. The shells of this deposit are very friable, owing to the porous nature of the sands they are embedded in, and are, in many places, found chiefly as casts. These Thanet sands extend downwards to the depth of 90 to 100 feet, as I have proved in a well sunk at Stourmouth.'"
*
See Geologist, 1861, P: 213.
342
Mr. Prestwich, to whom every gcologist must be deeply indebt ed for his knowl edge of the lower tert iaries, has so ably descrih ed the sections exhibited here th at I cannot do bet ter than quote his ge nera l conclusions on these interestin g format ions :-" The Thanet san ds are the lowest of th e eocene strata of England, and Mr. Prest wich has shown t heir connection w ith the Lower Landenian beds of Belgium, describe d hy Sir Charles Lyell. Th e latter are characterized by a g ree n sanrl and sandstone, t ermed glauconite. Th e connecting link between t he cret aceous and tertiary strata is w ant ing in England, an d is represented on th e cont inent by the Meestri ch beds. 'I'he chalk appears to have been ext ensively denud ed previous to t he deposition of t he lower eocene beds." P assing along t he cliff, towards He rne Bay , we find this Qed (the Thanet sands) gradually dip, until at Bishopstone it is lost in t he base of th e cliff. Immediat ely over th is deposit is anot her (here very similar in lith ological cha ra ct er where t he two meet). It is the middle of t he lower or eocene London tertiaries, termed t he W oolwich beds, from being largely developed at ,Voolwich, where they form st rat a. of considerable thi ckness, consistip g of clay, sand s, and pebble-beds. Near H erne Bay th e pebbles are, for the most part, wanting , the beds being composed almost enti rely of a quartzose ochreou s sand, at parts inclining t o ferruginous, and in the lower part much mixed with a green sand. Near W oolwich this series is distin guished by a mixture of marine and freshwat er shells. Among th e latter Cyrena cuneiformis is very common. H ere it assumes more of a marine characte r ; traced in a west erly direction from H erne Bay th is deposit assumes a more and more fresh wat er cha rac ter. Over thi s strat um we meet wit h anot her deposit , consisting of ligh tcoloured sands, with concretionary mass es of red san d, conta ining much iron, and at it s lower part thin pebble-beds. I am not quite sure if the thin pebble-bed between this and the Woolwich beds should belong t o the upper or lower series. This deposit is termed by Mr. Prestwich th e basement-bed of th e Lond on clay. Near Cante rbury parts of th ese beds have been quarried for smeltin g- purposes; and it is not uncommon to find " colliers " ballasting back to th e north with thi s iron.
343
Before reaching Bishopstone the London clay proper has made its appearance over this light-coloured basement-bed, with which it contrasts greatly in colour and appearance; and from this point the lower beds dip under towards Herne Bay, where the London clay forms the entire cliff. Owing to the great contrasts of colour and difference of the strata forming these cliffs, they present a most picturesque appearance. The lower sandy beds fall to the waves only from being undermined, and present a nearly perpendicular face, the concretionary masses of sandstone forming a pavement to the beach. The London clay, on the other hand, is constantly slipping down, and presents an irregular inclined plane. See Fig. 2. The London clay this side of Herne Bay is not very fossiliferous, but abounds in selenite. I have made little mention of the fossils to be found here, but the collector must possess much patience if he hopes to transport the shells from these beds to his cabinet. The Thanet Sands abound with fossils, but in these will be found few species-Cyprina Morrisii, being by far the most common in the whole series; Thracia oblata, Panopeea, Cytherea orbicularis. These are the most common. In the Woolwich beds Corbula, Dentalium, Cuculleea, and Cyprina being common. Large masses of silicified wood, often bored by Teredo, are found in this and the Tbanet Sands, some of which was procured from Reculver by the excursionists. In the Basementbed many fossils are found in casts in the concreted masses of iron-rust and pebbles. For a more detailed account of these deposits, I must refer my reader to the excellent .papers on the Thanet Sands and Woolwich beds by Mr. Prestwich, in the Geological Society's Journal. I will conclude this paper with a description of the drawings annexed, which, being not mere diagrams, but careful drawings taken on the spot, will give you a better idea of the appearance of these cliffs than any description, and will, I hope, guide the tourist in his search of the geological sections of this cliff. Fig. 1 represents the cliff about one mile west of Reculver, tho towers of which are seen in the distance. On the top of the cliff at a we have a drift-gravel, from which, most probably, the flint 2 F
344
implements found here have been derived. Beneath this, b represents the basement-bed, but little shown, however, but containing, beside pebbles, some tabular blocks of sandstone. Then, at c the Woolwich beds, composed here almost entirely of light-coloured sand, and forming the most part of the cliff. The junction of this bed with the Thanet Sands at d is very obscure; and, as a general rule in East Kent, I should say none but the practised eye could detect the difference. At the base of the cliff are seen large masses of argillaceous sand-blocks, exceeding rich in fossil shells; these belong to the Thanet Sands. They here resist the action of the waves better than the upper sand, which presents a perpendicular surface till undermined by the waves, when large masses fall, and the more sandy portions are speedily washed away. Quite at the base of the cliff are seen several sandstone blocks, derived from the Basement bed, b. Fig. 2 is a drawing of the sections shown at the Oldhaven Gap, looking towards Herne Bay. The top of the cliff is here composed of gravel-drift, marked a. The junction of this with the London clay is not seen in the Gap, probably from some drift and disturbance; but immediately beyond the dark London clay is distinctly seen capping the light sands of the Basement-bed, c. The London clay also extends considerably eastward of the Gap towards Reculver. The characteristics of the Basement-bed are here beautifully shown. The upper part of the section in the foreground is composed of this deposit. The light and almost pure sand is drifted by the wind, and at the corner leaves the ironstone blocks and concretionary masses in relief. The band of pebbles is likewise here distinctly marked, and forms the boundary-line between the Basement-bed and the Woolwich beds d, which latter compose the rest of the cliff.
Ordinary Meeting, Monday, November Brd, 1863.
Professor Tennant, F.G.S., President, in the Chair. The following donations were announced:" Smithsonian Report of 1861."