1. on the Lower Greensand and Gault of Folkestone

1. on the Lower Greensand and Gault of Folkestone

F. G. H. PRICE ON THE LOWER GREENSAKD, &0. 185 The following were elected Members of the Association :­ Baron de la Taille des Essarts; Francis Robert Morrison, Esq. j and John T. Young, Esq. The following Papers were read :- 1. ON THE LOWER GREENSAKD AND GAULT OF FOLKESTONE. By F. G. H. PRICE, ESQ., F.G.S., F.R.G.S, M.A.I. It is my intention this evening to lay before you a sbort account of' the Upper Neocomian and Gault of' Folkestone, than which place I mllY remark, for the benefit of those who happen to be un­ acquainted with the district, there is..no better locality on the south-east coast of England for the student of Cretaceous geology. If he makes that interesting old town his head quarters, he can take some most valuable and instructive rambles into the sur­ rounding district, where fine and extended sections of all the various stages of the Cretaceous beds, from the Wealden, west of Hythe, to the Upper Chalk, near Dover, can be found. THE LOWER GREENSAKD. The town of Folkestonc is situated upon the Folkestone Beds of the Upp er Neoeomian, In order to find the base of the Upper Neocomian series, we must go to Aldington Knowl, situated about five miles westward of Hythe, where the Atherfleld Clay forms a long inland cliff ex­ tending to Hythe, but, as we are informed by Mr. Drew, F.G.S., in the" Memoirs of the Geological Survey," the beds of the Kentish Rag have slipped down and covered it up, consequently it is seldom seen. It is about 30 feet in thickness, and may be seen at very low water on the shore ncar Shornc1iffe Battery. The Hythe Beds likewise make their first appearance at Aldington Know1; the lower ground to the south being occupied by the W cald Clays j very fine sections of the Hythe Beds or Kentish Rag may be seen in the quarries at the back of the town of Hythe, from whence the Rag-stone is extracted largely for building. It is a Iimestone of a bluish colour, very hard, alternating with bands or beds of clayey sand, locally termed "Hassock," which is very fossiliferous . A lengthy list of fossils from these beds may be seen in the "Memoirs of the Geological Survey: On the Geology SECTION OF UPPER NEOCOMIAN BEDS, FOLKESTONE. HYTilE BBDS. ~ Clayey Beds. ~." ..,' ,.' Oalcareouv Beet.. F . G. H. PRICE ON TH E LOW ER GRE E NS AND, &c. 137 of F olkestone, &c.," published with Sheet IV. of the Survey Maps. Thi s deposit has a total thickness of 60 feet. I have not examined th ese beds lithologically, althou gh I have visited the quarries several time s, and have made l\ considerable collection of fossils from the various beds in that formation. I shall at pr esent refrain from giving any list of the fossils collected until I shall have had time to work out the beds systematically. The Hythe Beds are succeeded by th e Sandgate Beds of the Upper Neocomian, which come on between Hythe and Shorncliffe j they dip N.N.E., until th ey finally disappear beneath the shore line a little eastward s of F olkestono H arbour. The Sandgate Beds are the next in the series j th ey consist of dark sands and clayey sands supposed to attain a thickness of 80 feet. They: rest upon th e Hythe Beds of the same formation. I have lately had an opportunity of visiting these beds in company with Mr. Jukes Browne, of Cambridge, and John Griffiths, with whom I examined them carefully at Folkestone, east of the harbour, and above the turnpike on the Sandgate Road. The result of our examination was, that we came to the con­ clusion that this division of th e Upp er Neocomian might be subdivided into four beds, to which I have affixed numbers. No. I.-The base bed is composed of black sands, which are well seen at spring tid es on the shore a little eastward of Folke­ stone Harbour j at the top of this bed many nodul es of iron pyrites occur, which frequently envelope specimens of Rhynchonella sulcata. The lower part of this bed I have not had an opportunity of exammmg , This bed is appropriately called the "Zone of Rhynchonella sulcata," as large numb ers are found in it. This zone is very fossiliferous. The following is a list of the fossils obtained from it :- Wood. Exogy~asinuata (Sow.). Cones. Gervillia anceps (Desh.), Rhynchonella sulcata (Paek.). Myacites plicata (Sow.), Asta~te ep, Pectuneulus sp, Crassatella Cornueliana (D'Orb.), Tellina..sp. Corbula sp, Trigonia sp, Cucullrea. glabra (Park.), Avellana inflata P (D'Orb.), Cytherea. sp, (ve~y abundant.), Dentalium sp, No.2. consists of dark green sand s, passing up into yellowish­ green sands. In the lower part of this bed, near Folkestone Harbour, 138 F. G. H. PRICE ON THE LOWER GREENSAND a few fossils have been observed, among which the following may be noted:- Coral. Lima Cottaldina (D'Orb.) Hemiaster sp, Ostrea frons (Park.) No. 3.-Black clayey sand-s-in parts very much resembling Gault. No. 4.-The top bed of the series consists of yellowish-green sands, which are' gradually succeeded by brownish clayey sands. The Folkestone Beds of the Upper Neocomian form the high ground from above Hythe to Folkestone, where, gradually dipping N.N E., they are lost beneath tide mark at Copt Point. From Sandgate to Copt Point they form an'<imposing cliff, often reach­ ing an elevation of from 100 to 130ft., resting upon the Sandgate Beds. In the upper portion, The Third Division, false beddings may be seen in many places. At Baker's Gap, which is situated about half way between Folkestone Harbour and Copt Point, an interesting example of a slight anticlinal is seen, eastward of which the beds dip away at a greater angle. I have divided these beds into four lithological divisions, of which- The First Division consists of a brown ferruginous sandstone of about one foot in thickness, holding a large quantity of phosphatic nodules, many of which have been much rolled, and have oysters adhering to them. At the extreme base of this bed large arenaceous nodules of brown sandstone occur, filled with casts of fossils, among which I have noted the following :- Coral. Lucina sp, Serpula articulata (Sow.). Trigonia sp, Corbula sp, Avellana sp. Cueullasa ap, J anira Morrisii, Lima sp. Ammonites, 2 sps, This bed forms an excellent division between the Sandgate Beds and Folkestone Beds. The Second Division is composed of a dark greenish clayey sandstone, reminding one very much of the "Hassocky" beds in the Hythe section of the series. It is about 2ft. in thickness, and is fossiliferous, the following having been found :- Serpula articulata (Sow). Ostrea frons (Park). Rbyncbonella sp, n sp, Waldeimia pseudojurensis. Pecten orbicularis (Sow). Avicula pectiuata (Sow). Janira Morrisii. The Third Division consists of about 60ft. of seams of coarse AND GAULT OF FOLKESTONE. 139 calcareous sandstone, varying in thickness from 2ft. to a few inches, all of which are interstratified with layers of loose yellowish sand. It is from this bed that the stone is extracted for building which is generally known as Folkestone-stone, Large white tabular masses of branching sponge are met with upon these rocks. About 20ft. up in this bed the sand partakes of a black clayey character, but .this is not constant along the whole horizon, but occurs only in patches here and there. It is apparently fossili­ ferous, as I met with Pecten orbicularis and a species of .A8tarte in it. Within 10ft. of the top of this bed a seam of chert occurs. In the top seam of rock I observed, remarkably large quantities of Hemiaster; partly covered over with a mass of the branching sponge before cited. Specimens of the latter my friend Mr. -Iukes-Browneobtained with a view of submitting them for examina­ tion, to Mr. W. J. Sollas, of St. John's College, Cambridge, who, as is well known, has made a study of the sponges from the Upper Greensand of Cambridge, and I trust that within a short time the result of his investigation may be made known, In this bed the following fossils have been met with ;- Polyzoa, Gervillie aneeps (Desh.). Hemiaster sp. Janira ata.a (D'oeb.), Spines of Micraster. Pecten orbicularis (Sow.), Goniaster sp. Perna sp, Pseudodiadema, Avellsna sp, Serpula plexus (Sow.). Waldheimia pseudo-jurensis. Avicula peotinata (Bow.). Ammonites sp. Exogyra sinuata (Sow.). The Fourth Division is the next and 'last bed I have to describe; it consists of an irregular seam of large rolled nodular masses of grit, composed of coarse grains of quartz, glauconite, jasper, lydian stone and phosphatic nodules. A considerable assemblage of fossils are obtained. from this bed, which is termed the Zone of Ammonites mammillaris. Its fossil contents are all more or less in the condition of rolled phospbatic casts, a list of which I give below. The seam is succeeded by about 4ft. of loose yellowish sands, which seldom yield any organic remains; this bed is capped by the line of nodules of sulphuret of iron which form the base of the Gault. I, roughly estimate the thickness of the whole for­ mation at about 70ft. The following is a list of fossils from this division :- L 140 F. G. II. PRIOE ON THE LOWEn GREENSAND Coral. Myacites plieata (Sow.). 1I0lastersp, Nuenla peotinata(Sow.). GoniaBter sp, Thetis loovigataP (Sow.). Pseudodia.dema sp, Trigonia Fittoni (Desh.), Terehratul& mouteuiana, Pteroeeraa biearinatum (D'Orb.).

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