The zones of the Lower Chalk of Lincolnshire

33:5

THE

ZONES

WITH

A

OF THE LOWER CHALK OF LINCOLNSHIRE.

LIST OF NEW RECORDS FROM THE CHALK OF THE COUNTY. By THE REV.

C. R.

BOWER AND ].

R.

RED

FARMERY.

[Read May 7, 1909.]

I.-INTRODUCTION. T I N G on the Red Chalk of England just fifty years W R Iago, the Rev. Thos. Wiltshire said of Lincolnshire: " There is a great geological darkness over that land, and much remains to be done in working out its fossiliferous deposits.':" Of the Lower Chalk of the county, notwithstanding the useful work which has been done, this remark is largely true to-day, especially from the point of view of the zoologist. The Memoir issued by the Geological Survey in 1887 t placed geologists in possession of a record of the main lithological features, but the list of fossils is disappointing, and the whole of the Chalk below the Actinocamax plenus marl is referred to one zone. This was followed in 1888 by an admirable paper ] by Mr. W. Hill, which has formed an excellent basis for subsequent work, and to which the larger Memoir.j; published by the Survey in 1903, seems to be almost entirely indebted for any additional light which it gives upon the zoning of this portion of the Cretaceous formation. That the system of zoning adopted by the latter was not altogether satisfactory to field geologists was indicated in a most suggestive paper II by Mr. T. O. Bosworth. But even he dismisses Lincolnshire in six lines, with an indication that darkness still broods over that land. This lack of progress may be traced to one or two mistaken ideas. They who only see Lincolnshire from the railway which traverses its" Fens" and "Marshes" fail to realise the charm of the exquisite views that lie hidden among its Wolds j and it is usually described as "flat and uninteresting." A similar partial view seems to have led geologists to regard the county as unfossiliferous and barren. Yet, just as exploration reveals an undulating country, with many a romantic scene, so the investigation of the Chalk geology rewards research with an interest not less fascinating. There are, however, difficulties in the way of * Ceot. .Assoc., 1859' +H The Geology of part of East Lincolnshire, including the country near the towns of Louth, Alford and Spilshy. (Explanation of Sheet 84,) r887' By A. J. Jukes-Browne. r ., On the Lower Beds of the Upper Cretaceous Series in Lincolnshire and Yorkshire." By William Hill. Quart. f o-urn; Ceol. Soc., vol. xliv (r888), p. 320. § JIeln. Geol. SUr'l!•• H The Cretaceous Rocks of Britain," vol. ii, "The Lower and Middle Chalk of England." By A. ]. j ukes-Browne, with contributions by William Hill. II II The Zones of the Lower Chalk." By T. O. Bosworth, Ceol. Mag' J September. 1906. PROe. GEOL. Assoc., VOL. XXI, PART 6, 191O·J

25

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the field geologist. Thus, practically all the exposures are limeor farm-pits, many of which are grassed over-lime-burning being a declining industry, and marling (which was much in vogue a quarter of a century ago) having fallen into desuetude. * Moreover, the lithological features are not constant over any greatly extended area, and may readily prove a source of confusion to the unwary. Here, however, the value of zonal collecting is demonstrated. For i1)stance, the two pink hands which occur in the neighbourhood of Louth have hitherto been referred to the same zone, and either might be mistaken for the other in any given section where only one is visible. But each has its own distinctive fauna, and, for reasons which will appear later, we have no hesitation in suggesting that in subdividing the Lower Chalk, they should be placed in different zones. With this brief introduction we propose to give a General view of the fauna of the Lower Chalk of Lincolnshire in relation to its lithological divisions j then to deal with the Zonal value of the Echinoderms, and the horizonal distribution of their various forms j and finally to give some Notes on the Sections, with records and a general table of fossils. II.-GENERAL VIEW OF THE FAUNA IN RELATION TO LITHOLOGICAL DIVISIONS. The presence of the two pink bands has one distinct advantage. It facilitates the classification of fossils obtained from different horizons before the collector formulates any theory as to zonal divisions. This has been the method adopted by the writers, and the following paper contains the results of careful observations from about 50 sections. The greater detail in lithological division which is apparent here seems to them to supply a link in the evidence which is necessary for a solution of some of the problems in zonal geology presented by the Lower Chalk in other parts of the country. The typical succession of the beds downwards may be tabulated as follows: X. The marl-bed usually referred to the zone of Actinocamax plenus, with chalk rubble at base. IX. The upper pink chalk. VIII. Thick beds of whitish-grey chalk. VII. Hard grey chalk with bed of Gryp7ta:avesicularis at base. VI. Broken whitish-grey chalk. V. Lower pink marly chalk. IV. Thin bed of grey marly chalk, with white course at base. III. Hard grey chalk (" Totternhoe Stone "). II. Hard blue-grey chalk, with marly partings. I. Hard gritty chalk, with" sponge-bed" at base. *

See" The Uses of Lime."

Board of Agriculture and. Fisheries, Leaflet No. 170 (lgo7).

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335

THE LOWER BEDS.

The lowest bed of the series is the yellow" sponge-bed," which rests upon the Red Chalk or Hunstanton Limestone. This is succeeded by a stratum of Inoceramus-grit. The dominant fossil is Holaster subglobosus/ and a somewhat pyramidal form of Discoidea cylindrica with pentagonal base also occurs. The Holaster is not uncommon in the bluish-grey beds above, which also contain Turrilites scheucheerianus, Pleurotomaria perspectiva, Discoidea cylindrica, and Salenia austcni. The local representative of the Totternhoe stone is by far the most fossiliferous stratum below the pink bands. As far as our experience goes, this is the lower limit of the occurrence of Offaster spll(cricus, which at this horizon has a relatively thick test. Here also we have collected our largest specimens of H olaster subglobosus. This bed in some parts, graduates into the. somewhat marly bed which occurs between It and the lower pmk chalk, and we have obtained the following fossils, amongst others, from these two members of the series: Grypkaa vesicularis, Pecten orbicularis, Rll)'ncllonclla mantelIiana, R. grasiana, R. martini, T'crebratula obesa, Terebratulina ornata, Serpulse, Ditrupa articulata, Discoidea cylindrica (pyramidal form), Salenia austeni, Cidaris dissimilis (spines). A special feature is the abundant occurrence of large Ammonites (Puzosia sp.), chiefly in bands lying on the top of the" Totternhoe Stone," but we have seen the same fossil still higher, in the lower pink band. THE LOWER PINK BAND.

This striking feature of the Lincolnshire Lower Chalk is quite peculiar to the central portion of our district, an area not more than twenty miles across. It would, in many cases, be more correctly described as a pasty marl containing nodules of chalk than simply as a coloured chalk j and often it is quite shaly. The fauna of this interesting stratum is sharply distinct from the faunas of the beds above and below it, and a few hours' investigation will amply repay the collector. Mr. C. S. Carter, of Louth, was the first to observe the abundance and constancy of the occurrence in this bed of a T'erebratulina, which is its most characteristic fossil, and on his pointing this out to Dr. A. W. Rowe, the little brachiopod was identified as Terebratuiina ornata. Associated with this is an abundance of a rather small T'erebratula which does not occur very frequently in the beds above or below, but is quite characteristic of the lower pink band. Dr. Rowe kindly examined specimens and gave his opinion that they were not true T. semiglobosa, but! suggested that they were a passage form between T. carnea

C . R. BOWER AND]. R. F ARMERY ON

and T. semiglobosa. H olaster subglobosus is common, but in size not so lar ge as many examples from the "Totternhoe St one." Discoid ea cylindrica and D. subu culu s occur, and spines of Cidaris dis similis are common. We al so record C. hirudo (spines), GrYP/Ul?a v esicularis (common), O. /tippopodium, Plicatula inflata, P. sigillina, T erebratulina striata, K ingm a lim a, R hyncltonella martini , Serpula umbonata , etc., and scales of N ear hombolepis punc tatus, recor ds of the la st having hithert o been confined to the south 'of England. In view of the alm ost total restriction of T crebratulina ornata to the lower pink ban d, the cha racteristic f orm of the T erehratula we have mentioned, and the form of H olaster subglobosus almost equa lly distinct on compa rison with the fossils yielded by the beds above and below, we are at a loss to und erstand how even a most cur sory examina tion could have led to the remark made by Mr. Jukes-Browne in the Memoir of the Geological Survey, * that the fo ssils of the pink band s are " of tlte same species as cha racterise the cha lk above and below, differi ng neith er in size nor form from the usual individual s of their species." It will ap pear even more clearly as we proceed that this statement is especia lly erroneous when applied to the lower pink band. T HE I NTERMEDIATE B E D S.

Above the lower pink band we have a whitish-grey cha lk, usually of a brok en nature ; and still higher, at the base of the f airly thick strata next to be describ ed, there lies a bed of extr emely hard grey cha lk, whose lower limit is mar ked by a line of Gry p/uea uesicularis , which we have fo und to be remarkab ly consta nt at about f our feet above the lower pink band. We sha ll see reason to suggest th at this is an important dividing lin e, if dominan t forms are to determin e zona l divisions. The f auna of these bed s, though meagre.. is very significant. H ere, so far as. our observations go, is the up per limit of H olaster subglobos us. H olasier trecensis has not yet appeared, and the beds above and below might be differenti ated by means of the fo rms of Discoidea and the thickn ess of the test of Of/aster sP/uuicus alone. T HE UPP ER PINK BAND .

The faun a of th is ban d is very limited as to number of species, but is cha racteristic. . Sp ecimens ar e abu ndant, but generall y in bad preservation owing to crushing, which undoubtedly has. much to do with the conf usion that has ar isen in regard to some forms with which we sha ll deal lat er. The domina nt fossil is. H olaster trecensis , which is everywhere abundant, and is closely associated with the th in-test form of 0 ff aster sP/uu icus and with • M m,. Geoi. SU rTJ. , "The Geology of E ast Li ncolnshire " (, 887), p. 37.

THE ZONES OF THE LOWER CHALK OF LINCOLNSHIRE.

337

-distinctive forms of Discoidea cylindrica. We find little distinction between the fauna of this band and that of the stratum of whitish chalk to which it succeeds, but fossils are less abundant in the latter. THE ACTINOCAMAX PLENUS MARL. From its position in the series, this bed was early inferred to be the local equivalent of the Actinocamax plenus marl so well known in other parts of the country. Mr. Hill recorded that the zone fossil was readily procurable in the quarries at South Ferriby, but the only evidence of its occurrence in any other part of the county was the lower half of a specimen obtained by Mr. E. Hall from one of the pits on the London Road on the south side of Louth. Fortunately we have been able considerably to extend the area of its known occurrence. In 1907, at our request, Mr. J. W. Wood, the proprietor of one of these pits (No.6), made -diligent search while the marl bed was being worked, and found about half a dozen specimens, all of which have been identified; and later in the same year Mr. C. Davies Sherborn also found it in the same district. Since then we have found it in situ not only at South Ferriby (No. 34), in the extreme north of the county, where we obtained four specimens, but at South Thoresby (No. 19), almost at the southern limit of the Lincolnshire chalk area, and in the pit adjoining Mr. Wood's, and now owned by Mr. \Y. Strawson (No. 17), in the central portion of that area. Other characteristic fossils of this bed are a very flat form of the circular-based Discoidea cylindrica, Rlzynclzonella plicaiilis, Lima asp era, Terebratula semiglobosa, T. biplicata, T. carnea, and abundant fish remains. The variability in the coloration of the marl is notable. At Ferriby the central portion is black, between layers of a slaty colour. Near Caistor the colour is much lighter, but farther south, in the neighbourhood of Louth, it changes to a dark blue-grey with a reddish base. Still farther south, in a pit (No. 25) about a mile and a half west of South Ormsby, the marl is almost entirely purple, without any evidence of grey; and at Claxby (near Alford), in the extreme south of our area, it has changed to a drab-grey. IlL-THE ZONAL VALUE OF THE ECHINODERMS OF THE LOWER CHALK. The zonal nomenclature adopted by the Geological Survey for the Lower Chalk of Lincolnshire seems to us to be unsuitable. It is certainly not in accordance with the fossil evidence. If the dominant fossil is to be taken as the guide-which is the only logical course-then both Of/aster splza:ricus and Ammonites

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uarians must be ruled out of court. The latter is so rare that we have encountered only one example in the whole of our work, though it has been made the object of the most diligent search. Nor is Of/aster spha:ricus more satisfactory. It does not dominate the zone to which its name has been applied, and its retention can only serve to perpetuate an arbitrary division which, though certainly marked off by the vertical range of this fossil, is not justified by a consideration of the total assemblage of the fossils in the beds throughout which it occurs. It will be recollected that the Memoir* draws the line between the two zones at the base of the Totternhoe Stone, but Mr. Bosworth, in the paper already referred to, t gave cogent reasons for placing it higher. He, however, concludes that neither Holastcr subglobosus nor H. trecensis is fitted for zonal use. But the link in the chain of evidence supplied by a study of the Lower Chalk of Lincolnshire, suggests that the use of the names of these two fossils might be made the basis of a zonal scheme which would apply to the whole of the Lower Chalk area of England. It is surely better to base our nomenclature on the general mode of occurrence of the fossils throughout the country, than to fix the limits of our zones and then choose the fossils by which to name them. For what are the facts? It is very clear, from the analysis of the records presented by Mr. Bosworth, that throughout the whole area of the Lower Chalk of England Holaster subglobosus does not occur in the upper beds of the zone to which the name of this echinoderm has been applied, with certain not very weighty exceptions-the Isle of Wight in the extreme south, where it is associated with H. irecensis, and Lincolnshire and Yorkshire, the most northern portion of the area, "where it is so rare in the beds above [i.e., above the zone of A. varians] that Offaster spha:ricus is used as the zone fossil in its stead." Now, in Lincolnshire, H. subglobosus is not at all uncommon in the Totternhoe Stone and in the lower pink band, both of which are included in the zone named after Of/aster sp haricus owing to the supposed rarity of H. subglobosus, but we have no hesitation in testifying emphatically to the rarity of H. sub globosus in the uppermost beds. Indeed, so far as our experience goes, it is absent from these beds. The only recorded exception of which we are aware is the statement by Mr. W. Hillj that Holaster subglobosus was not uncommon in the lowest bed (IS or 16 feet below the .4.. plenus marl) at the quarries near Barton-on-Humber (South Ferriby). This being higher than we had traced H. subglobosus anywhere else in the county, we felt confident that some mistake had been made, especially as a visit to the quarry * Mem. Geot. Sero., t Ante. p, 333.

H

The Cretaceous Rocks of Britain," vol, ii (1903).

:I: Qua,t./ourn. Ceol. Soc., vol. xliv (r888" p. 230.

THE ZONES OF THE LOWER CHALK OF LINCOLNSHIRE.

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resulted in our finding H. trecensis not uncommon, while we saw no sign of H. subglobosus. On our writing to Mr. Hill, informing him that we were preparing this paper, and felt some difficulty in regard to that matter, he very courteously consulted his field notes, which he quotes as follows: " Echinoderms are fairly common, but difficult to get out in the base of the pit. H. sub. globosus, Discoidea cylindrica (?) and H. trecensis," Mr. Hill adds: "Your letter makes me wonder whether I really intended to put the note of interrogation before H. subglobosus instead of trecensis," (The? is Mr. Hill's.) In any case, Holastcr subglobosus must be rare in the uppermost beds of the Lower Chalk, and the sporadic occurrence of the specimens at that horizon in two localities would not invalidate any scheme of zoning. Holaster trecensis, on the other hand, appears to be limited to the very beds from which H. subglobosus is absent. It is true that H. trecensis is recorded in tables as having been found in the Lincolnshire equivalent of the Chalk Marl, but we have been unable to discover from Mr. Hill's paper or from the Memoir of the Survey* where it oc:urre:f, and it is onlv doubtfully recorded from the same honzon III Yorkshire. If the recorded occurrence of H. trecensis in the Chalk Marl of the Isle of Wight is comparable with the records for Lincolnshire and Yorkshire, then all three records are not of much weight in any scheme which recognises dominant forms as the guides to zonal terminology. From the uniform occurrence of H. trecensis in the uppermost beds of the Lower Chalk of Lincolnshire and our definite discovery of this fossil in the extreme north of Lincolnshire at South Ferriby, we venture to suggest that further research in Yorkshire might reveal its occurrence in that county at the same horizon. "In Lincolnshire," says Mr. Bosworth, "H. trecensis is found above the Burwell Rock [ = Totternhoe Stone], and it is also recorded from the Chalk Marl, but I do not know whether it is common at that horizon." We have not recorded it in a single instance, and our experience in Lincolnshire coincides exactly with his in Cambridgeshire, where, he tells us, "there appear to be two very distinct zones," the upper" abounding in H. trecensis , but with no H. subglobosus "; the lower" with H. subglobosus and no H. trecensis." Horizonal Distribution of Ec1linoderms.-Not only are the above remarks true of Holaster subglobosus and H. trecensis , but the echinoderms associated with them are of distinctive forms. Discoidea cylindrica, which occurs commonly from the base to the summit of the Lower Chalk, is of two chief forms. First, a variety of which the base is pentagonal, the rest of the test diminishing somewhat rapidly from base to apex so as to form a sort of low cone or pyramid (Plate XXVII, Figs. 5 and 6). Secondly, a more or less hemispherical form with more circular * See enre, p.

233-

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C. R. BOWER AND]. R. FARMERY ON

base, though in the taller varieties of this form the base is somewhat pentagonal (Plate XXVII, Figs. 2, 3 and 4). Both the distinctively pentagonal and the hemispherical forms undergo a general progressive flattening as we ascend the series of beds in which they occur, so that the most discoid specimens of all are found at the highest point to which the two chief forms separately reach. Of the numerous specimens collected by us, the upper limit of the pentagonal form (pronouncedly discoid) coincides with the lower limit of H. trecensis, The upper limit of the hemispherical, circular-based form is the Actinocamax plenus marl, in which the specimens show an extreme diminution in elevation (Plate XXVII, Fig. r), rendering them comparable as regards that characteristic to the discoid pentagonal forms. In fact, the horizon marked out by H. trecensis might almost, so far as our fossil evidence goes, be delimited by means of the Discoidese, Forms of intermediate height occur abundantly (Plate XXVII, Figs. 3 and 4), but we have never found the typical pentagonal form above the base of the beds in which H. trecensis predominates, and there it is the extremely flattened form. The characteristic pentagonal-based form (low conical) (Plate XXVII, Fig. 6) has only been found by us in the lower division of the chalk in which H. sub globosus is the dominant type. This shapevariation is found in the very lowest beds. Higher up, above the Totternhoe Stone, the tall dome of the hemispherical form (Plate XXVII, Fig. 2) with somewhat pentagonal base comes in, and higher still there is a progressive approximation to circularity of base (Plate XXVII, Fig. 3) accompanied by a diminution in the elevation of the test. The two main forms do not begin to appear at the same horizon, nor does the upper limit of the one coincide with the lower limit of the other, so that there is an intermingling of the two forms at certain horizons, but we have never found the flattened circular-based variety (Plate XXVII, Fig. r) in association with the typical pentagonal form (Plate XXVII, Fig. 6). Offaster spluuicus presents differences in the thickness of its test, which we find greatest in the Totternhoe Stone, to which, indeed, the occurrence of the thick-tested variety appears to be limited. The thin-tested variety is common in association with H. trec ensis in the upper beds, so that here again we have an echinoderm which serves as a guide fossil in association with either of the dominant forms-H. subglobosus and H. trec ensis. In reference to Offaster sp haricus, one specimen we have obtained is of more than ordinary interest. I t will be recollected that the general shape of this fossil is, in the words of Mr. Jukes- Browne, " so similar to the more globular forms of Echinocorys vulgaris that the imperfect specimens obtained by the fossil-collector of the Geological Survey were mistaken for that species, and catalogued

THE ZONES OF THE LOWER CHALK OF LINCOLNSHIRE.

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under that name in the Survey Memoir (Explanation of Sheet S4)." This quotation is taken from an appendix to Mr. Hill's paper, in which the echinoderm in question is described by Mr. Jukes-Browne as a new species of Holaster.* Subsequently, however, it was discovered that as early as 1867 it had been described as Offaster spltaricus by Schluter, and under this name it appears later in the Memoir of the Survey. t In the specimens figured on the plate which accompanies Mr. Hill's paper the periprocte is shown to be distinctly supramarginal, but the specimen in our possession appears to demonstrate much more clearly the close affinity of Off aster s-p liaricus with Echinocorys. The periprocte in this specimen is marginal, and when the fossil was shown to Dr. Rowe and Mr. C. Davies Sherborn they agreed that at first sight it might be mistaken for Ecltinocorys, the former pronouncing it to be Offaster spltaricus of strong affinity with Ec hinocor ys, This specimen was found in the upper pink band in Mr. Wood's pit at Louth (No.6), and other less perfect specimens appear to have the same characteristics. Our most perfect specimen is 4"4 em. in height, with a greater diameter of 5'2 ern. and lesser diameter-of 4'3 cm. It may not be without significance that at the lower limit of the occurrence of Offaster spltaricus we also find H. subglobosus of large size, with periprocte not quite so high as in typical specimens of H. subglobosus-suggesting passage forms between H. subglobosus and O. spltaricus. We have previously referred to the character of H. subglobosus as it occurs in the lower pink band, and this fossil appears to tend towards a pyramidal form in the highest beds in which we have found it. We may add, before leaving the subject of the Holasters, that we are able to record the occurrence of the tall variety of H olaster resembling Eclzinocorys at South Ferriby. The general results of the foregoing may be tabulated, taking H. subglobosus and H. trecensis as provisional zonal fossils (see

p. 34 2 ) . Our experience in Lincolnshire quite corresponds with the statement of Mr. Bosworth that the fauna of the Burwell Rock <= Totternhoe Stone) is typical of the lower of the zones into which the chalk below the A. plenus marl has been divided. We have been fortunate enough to collect Salenia austeni, hitherto unrecorded for the county, from three sections, the specimens being taken from both the Tottcrnhoe Stone and the equivalent of the Chalk Marl. In any subdivision of the zones, the lower pink band would certainly deserve to rank as a sub-zone, for which Terebratulina ornata would supply a suitable name. This brachiopod we have found sporadically in all the beds below, even in the Red Chalk (= Gault); and a specimen which we * Quart.]ouNt. Geol.

Soc., vol. xJiv(1888), p. 355.

1- •• The Cretaceous Rocks of Britain," vol. ii (19°3).

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Zone of R. Cuvieri. Upper limi t of D . cylindr ica (flat, circular) .

A . plm us marl.

Upper pink band. Discoideee hem isphe ric (rather low if circularbased, extre mely discoid if pentago nal) . Whitish-gre y chalk.

Hard gre y chalk. Whitish broken chalk . Lower pink band.

" Totternhoe Stone."

Zone of H . trecensis, Guide Fossils: H . tr ecensis, O. sp htel'icus (thin te st) , D . cy/indrica (circular, or discoid pentagona l) .

Lower limit of H . tre censis, Upper li mit of H . subg /obosus.

{

- - - > Gryplztl'a bed.

}-

1- - -

Smaller H . subg/obosus. Upper limit of O. spntl'I'icu s (th ick test) with large H . subg/obosus (cordiform).

{-

1_

Zone of /[/oborus. D. c)'/i,ldr ica ( typica lly

pent ag onal) .

H . rubg/obosus (mediu m).

Hunstanton limestone.

Fo ssils : H . subg/abosus, O. sphtericu s (th ick test) . D. cy/ind r ica (ta ller

pentagon al dome) .

H ard bluish-grey chalk.

I nocer a mus and { " Sp onge " beds .

H. subGuide

_

and

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found in the A. plenus marl at Louth was recognised by Dr. Rowe as a modified form of the same species. But nowhere have we found it in anything like the great profusion in which it occurs in the lower pink band. We venture to suggest that such a subzone would hold good, even in localities where the bed is not coloured pink. Mr. Bosworth mentions a well-marked band of Rhynchonella mantelliana as occurring a few feet above the Burwell Rock, associated with various fossils, consisting principally of Ser-pula umbonata, Terebratulina nodulosa, and Cidaris dissimilis. This is in striking correspondence with what occurs in Lincolnshire, where we find R. mantelliana common in the marly bed between the Totternhoe Stone and the lower pink band, the last named yielding abundant evidence of the fauna mentioned, if we read T. ornata instead of T. nodulosa. In some cases we feel certain that T. ornata has been recorded as T. gracilis .. for instance, at Welton, opposite Cross Keys Inn (Pit 38), the Geological Survey* recorded T. gracilis as occurring in the marly beds (not coloured pink) at the same horizon, and we have found T. ornata to be common in this particular section. The following table shows the relations between the schemes of zoning adopted by the Geological Survey and .Mr, Bosworth, and that suggested in this paper for the Chalk below the A. plenus marl in Lincolnshire: Survey Memoir, 1903.

Mr. Bosworth,

\

1 906 .

Now suggested.

Ii 1

Upper pink and whitish-grey chalk.

Zone of Holaster trecensis,

I I

-..,----:---=--:--;--

Zone of

I

..Line()l GryphlFa.!. Lower pink band.

'sft::::,:

Two Holasters

Zone.

1

······I~,~~;;;~-:::i;:.:

" Tottern hoe Stone" ~~~ _ _

Lower grey chalk. Inoceramus and ,. Sponge" beds.

.1

_~ _ _.__

Zone of Ammonites uarians,

Ammonites uartans Zone.

* Mem. Geol. Surv., Explanation of Sheet 34, p. 44.

Zone of Holastlr subglobosus.

3 44

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TV.-NOTES ON THE SE CTIONS, A ND TH EIR FOSSILS. In this part of our P aper we give detail s of the work on th e va rious sections, and, in ord er to fac ilita te reference, we follow t he nu merical designation s rather than geographical distribu tion, which may readily be ascertained from th e Ord nance Survey maps. Section No . L-Grimsby R oad , Loutlt(Mr. P ad dison' s E xors. ' Pit).-The upper beds of the Lower Chalk, from the " T ott ernhoe S tone " to the A. pl enus marl , are well expose d in thi s section . A t hickness of onl y abo ut 2 ft. of the T otternhoe Stone is seen a t the bottom of th e pi t , and the lower pink band is here 4 f t. thick, the upper pink band being 12 Yz ft. in thi ckness. Bet ween the two pink band s th ere is a vertical distance of 18 Yz f t. occupied by hard whitish-grey chalk, and the line of gryphsea can be tr aced about 4 ft. above the lower pink band. The A . plenus ma rl, with its base of hard , whitish nodular chalk, is 2 ft . 9 in. in depth . There is a slight f ault , which may be a continuation of those seen at Hallington and H ubbard ' s Valley. The section is ca rried lower in Pit 20, which adjoins. P tychodus decurrens, Vert ebra of Shark, Gry pluea vesicuIaris, I noceramus sp ., T erebratula semiglobosa, T. d . semiglobosa, Te rebratulin a ornata, R ltynchonella martini , R. pUcatilis, Memb rani pora, Stomat opora , Echinoderm sp ine, Off aster spharicus, H olaster subglob osus, H. trecensis, Discoidea cylindrica. Secti on No. 2.- Hubbard's V alley, Louth (nea r W ater work s). - T his is not a " pit, " as stated in th e Survey Memoir, * but a valley- section, well exposed fo r a di stance of abou t 160 ya rds by the side of a pu bli c road. It inclu des the T ottern hoe Stone, and the upper pi nk band just app ears at one part of th e section. T he lower pi nk band is a stri king f eature. T he excavations ca rried out in J 9°7 , when the valley was presented to the town, ca used some of the chalk to be work ed, and we obtained a ta ll do me-shaped Discoid ea cylindrica fro m opposite the wat er works, and a cha racterist ic pentago na l-based form from just above the level of the stream in an excavation made fo r the drinking fountain f ar ther up the valley. The lin e of G. uesicuiaris is traceable at the usual height above the lower pink band . In the pink band we have observed th e large ammonite so common ju st above the Totternhoe Stone . Here, and in Pit N O.3, H olaster subglobosus, of ra ther small size, is common at the base o f the lower pink band , and our records for the bed between it a nd th e white course which cap s th e T otternhoe Stone include

*

H

The Cret aceous Rocks of Britain," vol. Ii, p.

22 J.

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Teredo amplzisbcena and Rltynclzonella manteliiana, T'erebratulina ornata is common in the lower pink band, and Cidaris spines are often found. We obtained the Terebratula cf. semiglobosa, so characteristic of the lower pink band, in beds immediately below it, a fact which, with the occurrence of Rltynchonella mantelliana and Terebratulina ornata, seems to point to an affinity between these two marly beds. Our list of fossils includes Ammonites (Puzosia ) sp., Inoceramus, Teredo amphisbcena, Ostrea hippopodiul/t, G, vesicularis, Plicatula inftata, P. sigillina, Rlzynchonella mantelliana, R. martini, Tereoratula semiglobosa, T. d. semiglobosa, Tcrebratuiina ornata, T. striata, Kingena lima, Serpula plana, H olastcr subglobosus, Discoidea cylindrica, Cidaris dissimilis (spines), and Cidaris sp. (spine). Section No. 2A.-Fislzer's Hill, Hubbard's Valley, Louth. -This is farther up the valley than No.2, and on the opposite side, facing the drinking fountain. It is a small, broken section, very dirty, and difficult to work owing to overhanging roots and branches. It is interesting, however, as affording us the first record for the county of Salenia austeni, which we found on the talus in May, 1907. The only other fossils which we record here are Rhynchonella mantelliana, T'crebratula semiglobosa, and an echinoid spine. Masses of Inoceramus fragments occur in the fallen blocks, but whether these blocks are from a small exposure higher up the hill, possibly referable to the zone of R. cuvieri, we could not determine. Section No. 3.-Hallington (at cross-roads about 2 miles from Louth).-This large, somewhat shallow pit, not now regularly worked, is the most fossiliferous we have investigated in the district. The lower pink band is accessible almost throughout, some distance below the top of the pit, and the lowest beds originally exposed (now hidden by talus) must be near the base of the Lower Chalk. The Red Chalk, which has been considered the equivalent of the Gault, is certainly exposed in the road cutting a little below the pit. On page 5 I of the Survey Memoir* we are told that: "In the road-cutting below the chalk pit at Hallington fragments of red chalk were observed in the bank, but whether these marked the outcrop of the basement rock, or of the lower pink bed faulted down, could not be determined." In 1904, however, Mr. H. Preston set the matter at rest by finding Belemnites minimus at this spot, and we are able to confirm this observation. The beds above the pink band in the pit are not readily accessible except to a very limited extent, and they appear to be * Memo Geol. Surv., H The Geology of part of East Lincolnshire" (Explanation of Sheet 84), by A. J. Jukes-Browne.

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very barren so far as we have been able to investigate, but the line of G. vesicularis about 4 ft. above the pink band can be traced. The pink band and the Totternhoe Stone yield richly, and the massive beds below are to some extent accessible, though the extraction of fossils is difficult. The thick-tested Offaster sphCEricus, large specimens of H. subglobosus, Pecten orbicularis, Terebratula obesa, and other large Terebratuia (so different from the rather small variety of the lower pink band), RhyncllOnella mantelliana, and R. grasiana occur in the Totternhoe Stone, above which is the usual line of Ammonites (Puzosia sp.). In the pink band Holaster subglobosus of smaller size is abundant; Cidaris dissimilis (spines), GryphCEa vesicularis, and Plicatula inflata are common; Pecten orbicularis occurs, and we have also found Discoidea cylindrica and D. subuculus in the same bed, together with the characteristic Terebratulina ornata and small Terebratula cf. semiglobosa. We know of only three specimens of D. subuculus found in the county, and all were taken here-s-one by Dr. Rowe and the others by ourselves. A Serpula, as yet unnamed, but well known at the British Museum, is somewhat common, as are fish vertebral, and it was here that we found scales of Neorhombolepis punctatus, which has hitherto been found only in Kent. The cast of Pleurotomaria perspectiva recorded below was taken from the talus, but from the character of the rock in which it was embedded we infer that it came from below the Totternhoe Stone. We record the following from this section: N eorhombolepis punctatus (scales), other fish remains (vertebral, teeth, scales, coprolites), Ammonites (Puzosia) sp., Pleurotomaria perspectiva, Ostrea hippopodium, GryphCEa vesicularis, Plicatula inflata, Avicula sp., Pecten orbicularis, Inoceramus crippsi, Terebratula obesa, T. semiglobosa, T. cf. semiglobosa, Terebratulina ornata, T. striata, Kingma lima, Rhynchonella grasiana, R. mantelliana, R. martini, R. plicatilis, Stomatopora, 1/1embranipora, Serpula ampullacea, Serpula (a pentangular sp.), S. plana, S. umbonata, Serpula sp. (unnamed), Ditrupa sp., Offaster sphCEricus, H. subglobosus, Discoidea cylindrica, D. subuculus, Cidaris bowerbanki (spines), C. dissimilis (spines), C. hirudo (spines), Asteroid ossicles, and Lima as pera, Section No. 4.-Redlzill, Goulceby.-A small, shallow, and now disused pit by the side of the road. The junction of the Lower Grey Chalk with the Red Chalk is shown in this section. The short list which we are able to give from the grey chalk here, of which about 10 to r a ft. is exposed, is interesting as including our only specimen of Ammonites uarians, The species are Ammonites uarians, Pleurotomaria sp., GrYPhCEa vesicularis, Terebratula semiglobosa, Holaster subglobosus, Discoidea cylindrica, Ventriculites im-pressus.

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Section No. 5.-Rowgate Hill, near Scamblesby.-A small, ill-exposed section in the base of the Lower Chalk, and showing the junction with the underlying Red Chalk. We obtained H olaster subglobosus here. Section No. 6.-London Road, Louth (11r. J. W. Wood's Pit). -This is the pit described as Mr. Larder's in the Memoirs of the Survey. It is worked for lime-burning, and a large, well-exposed section is accessible, including the whole of the beds to which we have alluded as embracing the range of H. trecensis, At the bottom of the pit is a thin marl band full of Grypllaa vesicularis, on which rests 4 ft. of extremely hard grey rock. That the Gryphaaline is at the same horizon as the similar line already described at Sections I, 2 and 3, and which we shall see also occurring at No. IS, is probable, as the Survey published a statement in 1887 that the lower pink band occurs about 3 ft. below it. Above this hard grey rock is r a ft, of whitish-grey chalk, between which and the A. plenus marl are beds (about 10 ft.) of pink and yellow chalk (the" upper pink "). We are able to record H olaster subglobosus from the hard grey chalk at the bottom of the pit, which is the highest horizon at which, so far, we have known it to occur. Fossils are not numerous in the whitish beds above, but these have yielded Of/aster spharicus, H. trecensis, Discoidea cylindrica, Terebratuia semiglobosa, Plicatula sigillina, Stomatopora, Gryphaa vesicularis, and Tereoratulina striata. In the pink band above the same fauna is found, but in relatively greater abundance. As regards the proportion in which the echinoderms occur, we may state that of 91 specimens obtained from this bed, 39 were H olaster trecensis; 38 Discoidea cylindrica, I I Of/aster spharicus, and 3 the Holaster resembling Echinacor ys. The proportion of H. trecensis compared with D. cylindrica is greater than would appear from these figures, as D. cylindrica is generally well-preserved, while H. trecensis is so often crushed that many specimens were not brought away. It was from this bed that the specimen described as an Of/aster spharicus with such a remarkable affinity to Ec hinacorys was found. Here, also, as mentioned previously, Actinocamax plenus has been found in the marl above the pink in greater abundance than has been recorded for any other section in Lincolnshire with the exception of South Ferriby. The marl also yields Rhynchonella d. cuvieri, R. plicatilis, Terebratuia biplicata, T. carnea, T. semiglobosa, fish remains, Cidaris (spine), Ostrea hippopodium, Plicatula sigillina, Inoceramus, Serpula plana, Discoidea cylindrica, etc. The pit adjoins Section No. 17. The following is our list from this section: Fish teeth and scales, Actinocamax plenus, Ostrea llippopodium, G. vesicularis, Plicatula sigillina, Inoceramus sp., T'erebratula biplicata, T. carnea, T. semiglobosa, Terebratulina d. ornata, T. striata, Rhynchonella cuvieri, R. plicotilis,

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Stomatop ora, Serpula plana, Serpula (unnamed sp.), Offaster spharicus, Holaster subglobosus, H. trecensis, Discoidea cylindrica, Cidaris bowerbanki, and Cidaris sp. (spine).

Section No. 7.-Tathwell (a well on Mr. J. E. Davy's farm). -This well was sunk to a depth of over 140 ft., and passed through White Chalk, and also through Lower Chalk, traversing the pink beds. We. record the following species: Pleurotomaria perspeetiva, Ostrea hippopodium, Gr yplia:« vesicularis, Pecten orbicularis, T'erebratula semiglobosa, T. d. semiglobosa, Rhynchonella martini, Of/aster sp haricus, and Discoidea cylindrica. Section No. 8.-Burwell (about 4;0 miles south of Louth). -This is a small pit in a field on the east side of the road from Louth to Burwell. The A. plenus marl is easily accessible, though it is near the top of the pit. The chalk below the marl, which is pinkish, is much broken and dirty. The base of the marl is exceedingly rich in fossils, chiefly brachiopods, which occur in pockets. In the marl, and just below, we found two specimens of the flat variety of Discoidea cylindrica, Our list includes Lima asp era, Inoceramus sp., Ostrea hippopodium, G. uesicularis , Rhynchonella martini, R. plicatilis, T'erebratula carnea , T. semiglobosa, and Serpula plana. Section No. 9.-Near Tathwell School.-The exposed part of this pit is chiefly in the R. cuvieri zone, talus covering the lower beds, except the A. plenus marl and a few feet of grey chalk below. In the marl we found Inoceramus and Asteroid ossicles, Section No. ro.-Claxby (near Alford), north-west from the Church.-A large worked pit, in the lower part of which the A. plenus marl and about 9 ft. of chalk below are exposed. The latter is not coloured pink, as in the neighbourhood of Louth, but it yielded Holaster trecensis and T'erebratuia semiglobosa. The base of the marl contained Rhynchonella plicatilis, and the quarrymen professed familiarity with A. plenus on our describing it, but we have not seen specimens. Section No. rr.-Pit in Wood, 2 miles west of Louth (north side of Lincoln Road).-A small section, with A. plenus marl showing near the top. The jointings in the chalk below are often filled with veins of calcite. The upper beds are pink. We obtained Ostrea hippopodium, Inoceramus sp., Rllynchonella mantelliana, R. martini, R. plicatilis, var. octoplicata, Terebratula semiglobosa, H olaster trecensis, Discoidea cylindrica, Cidaris boioerbanki (spine).

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Section No. Iz.-Entrance to Welton Vale, half-a-mile west of No. II.-This is a disused pit behind the lodge at the southern entrance of Welton Vale. The section is poorly exposed, being nearly overgrown with elder bushes and difficult to work. The lower pink band, however, and the Totternhoe Stone below, are accessible. We record the following species: Fish vertebra and other remains, Ammonites (Puzosia) sp., Actinocamax plenus, Belemnocamax boweri, Pleurotomaria sp., Inoceramus (very small, young), Pecten orbicularis, Ostrea hippopodium, G. vesicularis, T'erebratula semiglobosa, T. d. semiglobosa, T'erebratulina ornata, Rhynchonella mantelliana, R. martini, Serpula umbonata, Ser-pula (unnamed sp.), Ditrup« articulata, Holaster subglobosus, Discoidea cylindrica, Salcnia austeni, Cidaris hirudo (spine), Cidaris sp., and Asteroid ossic1es. [Pecten (Chalmys) fissicosta, Etheridge, roth June, 1969.] The Totternhoe Stone of this section is interesting as having yielded two specimens of a hitherto unknown Cephalopod. Mr. G. C. Crick kindly undertook to examine them, and he describes them as Belemnocamax boweri. See post page 360. Section No. 13.-Tibb's Inn, near Hainton.-A small, shallow exposure of the lower grey chalk at its junction with the Red Chalk. Our only record from the grey is T'erebratula semiglobosa. We found Terebratulina ornata in the Red Chalk. Section No. 14.-Donington-on-Bain, half-a-mile east of the railway station, near the northern side of road to Louth.-A well-exposed section of the lower beds of the Grey Chalk, the Red Chalk also being exposed at the base of the pit. Our fossils are Ammonites (Puzosia) sp., Inoceramus (z species), T'erebratula carnea, T. semiglobosa, RhynchonelZa mantelliana, Serpula (unnamed sp.), Hoiaster subglobosus, and Discoidea cylindrica. Section No. IS.-Donington-on-Bain, near No. 14, on the southern side of the road.-An old quarry in a grass field, which carries the section of Grey Chalk higher than that of No. 14. A marl band, about z in. thick, full of Gr yphaa vesicularis, is traceable round the upper part of the pit. It is similar to that at Hallington (No.3), and the chalk below is of similar nature. There is a slightly coloured pink band in the chalk, but a search in it for T'erebratulina ornata was without avail. It will be seen that the fauna corresponds with that of the Totternhoe Stone and the bed above it in other parts of our area. Ammonites (Pueasia ) sp., Inoceramus sp., Gryphaa vesicularis, Lima (Mantellum) elongata, Rhynchonella grasiana, Terebratula obesa, T. semiglobosa, Kingena lima, Discoidea cylindrica, and Cidaris (spine). PROC. GEOL. Assoc., VOL. XXI., PART 6, 1910.]

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Section No. 16.-Donington-on-Baill (Railway Cutting), about half-a-mile west of the Tunnel betw een Withcall and Donington-on-Bain. -There is a section of the lower Grey Ch alk above the Red at the top of the embankment. The chalk is very platy, but yielded one example of Holaster subgl obosus, and al so Ammonit es (Puzosia) sp. , In oceramus sp., Ostrea hippop odium, T crebratula semigl obosa, and Stomatopora. Section No. q.-LondcJ'Il Road, Louth (Mr. Strawsori' s Pit, on the east sid e of the road).-This pit is just north of the cemetery, and adjoins section No .6. It is described as Mr. Cla pham's in the Survey Memoir. * The section is chiefly in the White Chalk abo ve the A. plenus marl , and is visible along the side of th e pit which supports th e highway . The pit is large and not now worked, but th ere are obvious reasons why th e best exposed beds, being those which have the road above them, should not be disturbed. The pr esent proprietor, however, kindly permitted us to make a surface examination of the section without displacing the rock. The marl yielded two specimens of Actinocamax plenus with an adn ate ann elid, Lima aspera, T erebratula semiglobosa, and fish scales. Other fossils which we collected fr om the beds below are added in the following list: Fish scales, A ctino camax plenus, Pleurotomaria sp., Plicatula sigillina , Terebratula carnea, T. semiglobosa, S erpula sp. , Holaster trecensis , and Discoidea cyli ndrica. Section No. 18.-South Elkington (near brickyard).-This pit is chiefly in the zone of R. cuvieri. The A. pl enus marl is seen about 4 ft. above the base of the working. It yielded two fine teeth of Otodus, fish scales and fragments of In oceramus, but we failed to find Actinocamax pl enus. Section No. 19.-South Thoresby .-A large pit, still worked. the well -exposed section being bi sected by the Actinocamax pl enus marl, from which we obta ined the characteristic fos sils. The upp er pink ban d is well shown. We record from th is section Actinocamax pl enus, Terebratula cornea, T. semiglobosa , Holaster trecensis, ahd Discoidea cylindrica. Section No. 20.--St. Alary 's Lane, Louth.-This pit adjoins Section No. I, and carries the section much lower. There are 9 or 10 ft. of hard, bluish-grey chalk with marly partings below the Totternhoe Stone, which is here 6 ft. thick, whil e the lower pink band, above which the section is not accessible, is 4 ft. thick, with about 18 inches of marly chalk betw een it and the Totternhoe Stone. On one occasion three of the large ammo'litem. Ceol. SUnJ., "The Geology of part of East Lincolnshire," by A. J. Jukes· Browne (1887), p. 64.

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nites were visible at the top of the latter. The section extends upwards to the upper pink band. The Totternhoe Stone and the bed just above it yielded Ammonites (Puzosia) sp., Inoceramus sp., Pecten orbicularis, Tcrebratula obesa, T. semiglobosa. Rhynchonella mantelliana, and Of/aster s-p hcericus, The other fossils in the following list are from the lower pink band, and are characteristic: Ammonites (Puzosia) sp., I noceramus sp., Pecten orbicularis, Gryptia:« uesicularis, T'erebratula obesa, T. semiglobosa, T. ct. semiglobosa, Tcrebratulina ornata. Kingena lima, Riiynchonelia mantelliana, Serpula umbonata, Scr-pula (unnamed sp.), Of/aster splta:ricus, H. subglobosus, and Cidaris sp. (spine). Section No. 2I.-Driby Top.-A large pit, near five crossroads, 1 mile south-west from South Thoresby. There is a small exposure of the upper pink band and the A. plenus marl at the bottom of the pit. Section No. 22.-Belcllford Hill.-About IYz miles northeast of Belchford Church, on the south-east side of the road. A large, shallow pit in the base of the Grey Chalk, the deepest exposure being about 14 to 16 ft. Chalk very gritty and full of Inoceramus fragments, Red Chalk with characteristic fossils being exposed in patches in the lowest parts of the pit. From the grey chalk we obtained a fine specimen of Alectryonia ricordiana. Section No. 23.-lngs Lane, Belchford.-A small pit at entrance to a bridlepath near Ings Farm, 1 Yz miles north of Belchford. It resembles No. 22, exposing 2 Yz ft. of the Red Chalk, with Belemnites minimus, etc. The grey chalk is exceedingly barren save for abundant fragments of Inoceramus, and we found one specimen of Pleurotomaria perspectiva. Section No. 24.-Tetford lVood.-A large, deep pit, the lower portion of which is covered with talus. The section exposes the beds from the Totternhoe Stone up to the greyish-white beds between the two pink bands. In the usual position, about 4 ft. above the lower pink band, the band of Gryplta:a vesicularis is distinctly traceable, and the other fossil evidence obtained by us confirms the observations on this section made by Mr. Hill, who, however, did not visit it. Below the pink band we obtained RhyncllOnella manielliana, Terebratula semiglobosa, and a fish tooth. The rest of the fossils in the following list, with the exception of Grypha:a vesicularis, are from the Pink Bed: Fish tooth, Coprolites, Gryp haa vesicularis, Plicatula infiata, T'erebratula semiglobosa, T. cf. semiglobosa, Terebratulina ornata, Rhynchonella mantelliana, Holaster subglobosus, Discoidea cylindrica, and Cidaris sp. (spine).

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Section No. 24A.-Tetford Hill.-This is a roadside section, which should be ta ken as a continuation of Secti on No. 24. It furnishes an admirabl e illustr ati on of the difficulty which may arise through confusing the pink bands with one anoth er , or with the A. pl enus marl when th at marl takes a pink or red coloration. Here, on both side s of th e road, th e outcrops of pink bed s are seen j and as th ey are all of a more or less marly nature, thei .. determination can only be made by means of th e fossil s. In the adjoinin g pit (No. 24) th e lower pink band is clearl y Seel!. On the road above we get massive whitish chalk underl ying a pink bed containing Holaster trecensis and Discoidea cylindrica of the flattened form, so that th ere can be no doubt as to it s being the upp er pink band , though it is more shaly than we have seen that bed to be in any other section, and might easily be mistaken for the lower pink band. A little higher up the hill, on the opposite side of the road, the A. plenus marl appears, being of a deep terr a-cotta colour and about IS inches thick. Upon it rests a small exposure of R. cuvieri chalk, from which we obtained Ammonites peramplus and Inoceramus labiatus. We also record a fish tooth, Gryphcea uesicularis, Terebratula semiglobosa, Rhynchonella mantelliana, and H olaster trecensis, Section No. 25.-Soutlt Ormsby, Association Farm.-This is a disused pit with a kiln, about I Yz miles west of South Ormsby, on the southern side of the road from South Ormsby to Tetford Hill. A very peculiar band of red chalky marl runs round the top of the pit, graduating downwards into a deep terra-cotta coloured rock. Section No. 26.-BrinklJiU (I Yz miles west of Driby Top).A fine but shallow expo sure of the basement beds of Grey Chalk, with about 5 ft. of Red Chalk showing near a limekiln. The chalk is very gritty, but fairly fossiliferous. One specimen of T erebratulina ornata was collected from a place about 6 ft. above the Red Chalk, in the lowest bed , which is the lower limit of the range of this fossil, so far as we ha ve been able to find, except for the example from the Red Chalk which we record at Section No. 13. This pit has yielded the first reptilian record for the Lower Chalk of the county, we having been fortunate enough to find a tooth of Ichthyosaurus camp ylodon, Our list fr om this section is: Ichthyosaurus campylodon, fish tooth, Ino ceramus latus, I. tenuis, Lima (Mantellum ) dongata, 0 strea hippopodium, G. uesicularis, T'erebratula semiglobosa, Terebratulina ornata, Rhynclzonella cuvi eri, R. mantelliana, Stomatop ora, S erpula, Holaster subglobosus, Discoidea cylindrica, Cidaris (spine), Salenia austeni, Section No. 26A.-Brinkltill.-A small pit about 30 yards from Section No . 26, and in the same beds.

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Section No. 27. - WhitefJit.-The major part of this small pit is in the zone of R. cuuieri. The A. pl enus marl is of a very deep pink colour, and mig ht easily be mistak en f or the lower pin k band. F ossils scarce. Secti on No . 28.-Near Stenigot H all. -This section here in cludes the Red Cha lk at the base, and the local represent at ive of the T ott emhoe St one. Our fossi ls are a Cephalop od, i noceramu s (2 speci es), L ima elongata, RllyncllOnella cf. cuvicri , R. mantelliana, T ercbratula semiglobosa, Disc oid ea cylindrica. Section No. 29. -Swaby.- -A small pit ~ mil e south of the Ch urch, in the valley . Section much obscured by tal us. Red Ch alk at base. F ossils sca rce. Section No . 30 .-Ketsby.--A small pi t m the Lower Pi nk Chalk, two furlongs sout h of K etsby Mill. T he chalk is much faulted and cru shed , and f ossils are scarce. Lower bed s much obscure d by talus. Section No . 3I.-Witllcall Railway Station .- Th is is a SOmewhat long section, which has been exposed in cutting the railw ay. The T otternhoe Stone and the lower pink band a re both acces sible. From both of th ese we obtained characteristic fossils, and lima elongata occur red in both . Ammonites ( Puzosia) sp. was observed in th e usua l position, an d all th e ot her fossils in the following list were taken from th e pink band: Ammonites (Puzosia) sp., Pe cten orbicularis, Ostrea hipp opodium , G. ucsicularis, Lima (ManteUum ) elongata, T crebrattda scmigiooosa , T . ef. semigiobosa, T erebratulina ornata, Crania (?), S erpuia (unnamed sp .), S erp ula (pentan gular sp.), H olaster subglobo sus, Cidaris dis similis (spin e). Section No. 32.-Soutll F crriby (M r. Skelsey's Pit). -A large pit, covering about an acre. T he lower part of th e pit is ill hard white chalk , and about 14 to 16 f t. f rom the base is the A . PlOlUS marl, dark brown and blac k in the centre. The section is much f aulted. H olaster trecensis and O ff aster sp IlCl:ricus are f airl y common in the lo wer bed s, and f rom the marl we obtai ned a cl upeoid fish (probably new), I noceramus mytiloid es, R ltynchoncll a plicatilis , and T erebratula semiglobosa . \ Ve record fro m this section fish rema ins, Ammonites (large sp.), Gry jJ l/{co vesicularis, In oceramus mytiloid es, Terebratu!a semiglobosa, RltyncllOnella plicatilis, 0 ff aster spharicus, and D iscoidea cylindrica. Secti on No . 33. -S outll F erriby (M r. Robinson 's P it).Secti on same as N o. 32. We record Ammonites (large sp .), H olaster tre censis, an d Discoid ca cylindrica,

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J.

R. FARMERY ON

Section No. 34.-Soutlt Ferriby.-Section same as Nos. 32 and 33. Fish remains from the marl especially good, including Elopo-psi« crassus, Protasphyrcena sp., etc. Discoidea cylindrica is common in the chalk below. Our list includes Elopo-psis crassus, Protosphyrana sp., Coprolites, Actinocamax plenus, T'erebratula scmiglobosa, Rltynchonella plicatilis, Holaster trecensis, Holaster (having appearance of an Ecltinocorys), and Discoidea cylindrica. Section No. 35.-Grebby Hall.-A large, well-weathered old pit, showing Red Chalk at the base and Lower Chalk up to above the Totternhoe Stone, though there is no trace of pink coloration. Fossils: Teredo amphisbana, Inoceramus (2 sp.), Terebratula semiglobosa, T. cf. semiglobosa, Terebratulina ornata, Rhynchonella martini, H olaster subglobosus, and Ventriculites impressus. Section No. 36.-Grebby Hall.-Close to No. 35, and carries the section slightly higher. The Red Chalk is not exposed. Fossils: Scaphanorliynchus, Inoceramus sp., Terebratula semiglobosa, RltyncJlOnella cf. cuvieri, and H olaster subglobosus. Section No. 37.-Welton Parish Pit (near Alford).-A large lime-pit, east of Cross Keys Inn, in the Lower Grey Chalk, showing the yellow bed overlying the Red Chalk at the base. In the upper part of the pit is seen 24 ft. of firm whitish chalk with marly partings, surmounted by about 3 ft. of marl and rubbly chalk. Fossils: Ammonites (large sp.), Turrilites scheuchzerianus, Inoceramus sp., RltyncltOnella grasiana, T'crebratula cornea, T. semiglobosa, Verruculina sp., Stomato-pora, Membranipora, Holaster subglobosus, Discoidca cylindrica, Cidaris (spine). Section No. 38.-Candlesby.-A large old pit, near No. 37, in front of Cross Keys Inn, the section including the hard greyish beds below the Totternhoe Stone, and the equivalent of the Lower Pink bed, the last named being represented by thin-bedded rubhly chalk and a buff-coloured marl. In this bed Mr. Hill records T'erebratulina gracilis, but we find only T. ornata. We record the following species: Grypltaa vesicularis, Ostrea sp., Plicatula infiata, Kingena lima, Tcrebratula carnea, T. semiglobosa, Terebratulina ornata, Rltyncltonella mantclliana, Serpula (unnamed sp.), Holaster subglobosus, and Discoidea cylindrica. Section No. 39.-Candlesby (side of Cross Keys Inn).Adjoins Section No. 38, but carries the section lower, exposing the Red Chalk. Fossils: Terebratula obesa, T. semiglobosa, Serpula (unnamed sp.), S. umbonata, and Holaster subglobosus.

355

THE ZONES OF THE LOWER CHALK OF LINCOLNSHIRE.

Section No. 40.-Welton (near Alford, one mile west of village.-Much overgrown, but showing several small wellweathered bluffs. Not examined, but apparently in the Lower Chalk. Section No. 4I.-Cawkwell Hill, Scamblesby.-A very poor exposure of much-broken and dirty chalk. Fossils: Holaster trecensis, Discoidea cylindrica. Section No. 42.-Scamblesby (Mr. Wright's farm).-A good exposure in the lower grey chalk, close to the farmyard. Fossils: Inoceramus latus, Terebratula semiglobosa, Rhynchonella cf. cuvieri, and echinoderm spines. Section No. 43.-Caistor (3 furlongs south-east of).-This pit is mentioned in the later Memoir as having the variegated marl exposed at the bottom, but that bed is now covered by talus. Section No. 44.-Nettleton (~ mile east of Church).-An old pit, much obscured by talus. The A. plenus marl (about I Yz ft. thick) is visible at the top of the pit. In an exposed part of the section we made the following measurements: ft. 4

Broken whitish chalk Massive" Broken " " . . .. .. . .. Seam of chalky marl........... Broken grey chalk Talus, about .

2

..

..

.

6

016 2

10

Section No. 45.-Bully Hill, near Tealby.-An old kiln, in which the following measurements were taken: ft.

Clay and broken chalk Yellowish chalk Grey marl parting Firm white chalk Marl parting Firm white chalk ." Marl parting Broken chalk and marl Marl band Finn chalk

ins.

I

0

5

6

0

6

2

0

2

6

.. " .. . 0

2

I

0

Section No. 46.-One mile north-west of Ludford. A good section of the lower beds of the Lower Chalk, very gritty at top. Here we saw two large Ammonites. Section No. 47.-Pit near fourth mile-iron from Louth on the Louth and Horncastle Road. It is in zone of R. cuvieri, but in April, 19°8, we were able to examine the A. plenus marl at the very base of this poor section. We obtained a tooth of Sca plrano-

C. R. BOWER AND

J.

R. FARMERY ON

rhynchus, and fish scales such as are usually found in this marl. The marl has since become covered with talus.

In conclusion, our thanks are due especially to Dr. A. W. Rowe, Mr. C. Davies Sherborn, Dr. A. Smith Woodward, Mr. G. C. Crick, Dr. F. A. Bather, Mr. Wm. Hill, Mr. T. O. Bosworth, Mr. A. J. Jukes-Browne, Mr. C. P. Chatwin, and Mr. T. H. Withers for help in identifying fossils, the revision of proofs, or for information supplied.

TABLE OF FOSSILS. The list of fossils given for Lincolnshire in the Memoir of the Geological Survey, * which includes the records of Mr. Hill, shows a total of 53 species. As will be seen below, we record 70 species, of which 44, distinguished by an asterisk in each case, are not found in the previously published list. If we omit the Ammonites, most of which were too large to bring away, and, being casts, could not be satisfactorily identified, and also the Inocerami, many of which we have not been able to get definitely identified before the preparation of this paper, we get a total of 62 species compared with 44 species in the Memoir, and our own additions to the record amount to 43 species. In the following table we employ the following abbreviations: R.=rare. C.=common.

R.R.=rather rare. R.C.=rather common. {i

Q)

j'" •

..8 .

lo4

•

-~ti

, om g; I-- - - - - - j~~ E~ ~-a ~~ 0/;: ~E

~'-'

OP:;

~

~S'

wI>

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::>

----------------REPTILIA.

"'Ichthyosaurus campylodon, Carter

R.

PISCES.

"'Elopopsis crassus, Dixon *Protosphvrcena, sp. *Clupeoid Fish (probably new) *Neorhombolepts punctatus, Ag. Ptychodus decurrens, Ag. * Lamna appendiculata, Ag. Scaphanorhynchus "Otodus ... *Fish scales and vertebrae *Coprolites

R. R. !{.

R. R.

R.

c.

c.

c.

* A/em. Geoi. Surv., "The Cretaceous Rocks of Britain," vol. ii., by A. Browne, with contributions by William Hill, '-1903.

J. Jukes-

357

THE ZONES OF THE LOWER CHALK OF LINCOLNSHIRE.

TABLE OF FOSSILS-Continued. .c

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::> i-- - - -- --- - CEPHALOPODA.

Ammonites (Schloenb.) uarians, Sow.... ... " (Puzosia), sp. ." .. Turrilitts scheuchzerianus, Bose. ... Actinocamax plenus, Blainv. . " ... ... *Belemnocama» boweri, Crick

...

GASTEROPODA.

* Pleurotomaria perspectiva, Mant. LAMELLIBRANCHIATA •

.,. ..Ostrea hippopodium, Nilss, '"Gryphtea uesicularzs, Lam. *Alectryonia ricordiana, Coquand .,. Plicatula tnjlata, Sow.... slgillina, S. Woodw. * " ..Inoceramus crippsi, Mant. latus, Mant " mytiloides, Mant. "" tenuis (I), Man t. '" '"Pecten (Chlamys)jissicosta, Eth. ., orbicularis, Sow. " ..Auicula, sp. '"Lima aspera, Mant. ... .. " (Mantellum) donga!a, Sow. , Teredo amph1sbtena, Goldf. oo'

...

... ...

...

...

oo •

... ... ..

BRACHIOPODA,

...

"

...

...

...

... .. , ... c.

... ...

... . ...

...

oo.

... ...

...

... ...

• oo

... ...

...

...

..

...

... ... oo.

...

..

... .. Sow. .. * Sow .•.• ., semiglobosa; (cf.) semiglobosa ... .. * * Terebratulina ornata, Roem. obesa,

Il

" sp. .. Crania,

...

BRYOZOA.

..Ll!embranipo1'a ..Siomatopora

. ..

... ...

...

.oo

ANNELIDA .

• f)tirupa articulata, Sow. sp.

oo.

... ... ... ...

striata, David. non Wahl.

...

oo.

...

...

...

...

...

... ...

...

'"

...

Kingena lima, Defr, . ... RJz."nchondla cuvio'i, d'Orb. ." grasiana, d'Orb. ... * " mantelliana, Sow. martini, Mant. " plicatilis, Sow. "" "vaT. octoplicata, Sow. TtI'ebratula biplicata, Sow. ... carnea, Sow.

..

I

.. . ... ... R. ... ... C. ILR. ... ... R.R ... ... ... .. . ... ... R. ... ... ... ... ... R. ... ... ... ... ...

...

... R.C. C.

oo •

... ...

...

...

... ...

C.

...

C.

R.C.

...

"

R.C .

C. C. R.

..,

R.

oo'

RC. R.C. H.C.

..,

R.C.

C

...

... ...

R. R.C. ,

,

... .., ... ...

R

... ... ... ... ...

...

...

.. .

...

c.

R.C. R

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C. C. C. R.

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R.C .

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...

... ...

...

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...

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C.

...

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...

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RC. \ R C

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... R.

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C. R.R. C.

... C.

... R. oo •

.. . ... ...

R.

... ... ... R. ... ...

...

R.

OO'

R.

."

H.

...

.oo

R.

OO'

...

R.

oo •

...

,

C.

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... ... I ... ... ... I ... RR H. • .. . ... ... ... '"

... .. , ... ... ... .. ... .. ... I .. ... ... ... ... ... ." ... R.C. K.C. ... oo •

... ...

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IL

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... ... ... .. . ... R.R ... KR . ... ... .. . ... ... ... .. . R.C. ... .. . ... ... ...

H.C. R.R., R. R•

c,

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oo •

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...

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R.

... ... ... .., R.C. ... C. RC ... .. , ... ... c. ... ... .., R. ... ... C . R. ...

... ...

R.C.

... .. . ...

..

..

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oo • oo •

...

...

C. R. BOWER AND

J.

R. FARMERY ON

TABLE OF FOSSILS- Continllt d .

s

.a . c~ "c

,,0

~ cil - - - -- - - - -- - - - -1--ANN ELIDA-conlinui d. R. • St rpllia ampu l/acta, Sow. R. H. C. • plana, S. Woodw. K. H.C . um bonata, Mant. e. c. c. C. sp. (undescr ibed ) R. sp . (smooth pentan gu lar form) E CHI NO DERMATA .

• Cidaris bowlrbank,; For bes " dissimilis ; Forbes * " hirudo, Sorig . ... • Salm ia austeni, Forbes Discoidea cytindrica, Lam. • II suhueulus, Leske Offasltr sphlEncus, Schl, (= Hota ster ratundus, jukes-Be)... Holaster sub~/obosus, Leske " trecensis , Leym. " resembling Ec/unocorys Aster oid ossicles

H.

R.

C.

C.

C.

K. H. H. R. H.H. H.R. R .R . R.

IR.R. C.

C.

R. H.

K.R.

C. I

c. R.C

i c. R. H.

S r ON GID A.

• Ventricuhtes impressus, T. Smit h • Verru culina, sp.

R. R.

EXPLAN ATION OF PLATE XXVII. We have taken accurate measurements of numerous specimens of Discoidea rylindrica from the upper zone of the Lower Chalk, and find the avera ge fronto-posterior diameter of the test is 2'88 cm., and the avera ge heigh t 1'5 ern. The measur ements of a num ber from the lower zone give an average dia met er of 3'45 cm., and an average he ight of 2'08 em, Adopting the formu la ~ in order to ascertain an index of the ratio of he ight to diameter, we obtain a n index of 52'07 for the upper zone and 60'29 for t he lower. But in order to appreciate the characteristic differences, the shape of the profile of the test must be ta ken int o account. The most characteristic Discoidea of the upper beds is circula r in base a nd more or less semicircul ar in profile, while the most characteristic Dis coidea of th e lower zone is pentagonal in base and like a rather low cone or pyramid in lprofile. (See pp. 339-340 for zonal val ue of shape variation.) The figures are from ph otographs by Mr. C. W . J ohn son . FIG. 1.-The flat form of Discoidea cylindrica (circul ar based), from th A. plmus marl in Pit No.6. He ight: 1'4 cm. Diameter: 3'3 em, FIG. 2.-The tall dome-shaped form of Discoiaea cylindr ica from Hubbard's Valley (No.3), showing the great elevation of the test. The base is incipiently pentagonal. H eight : 2'5 cm. Diameter: 3'5 cm. FIGS. 3 and 4.-A typica l circular-based hemispherical Dis coideacylindr ica of medium elevation from P it No.6. Height: 2'1 em . Diameter : 3'4 em. FIG. 5.-Pentagonal base of one form of Discoidea cylindrica. This specimen was from Pit No . 37, and is hemi spherical in profile. Height : 1'8 em, Dia meter: 3'6 ern,

PROC. GIWL.

Assoc.,

VOL.

XXI.

PLATE

XXVII.

[Photo by C. W. Johnson, Louth. THE ZONAL SHAPE-VARIATIO:-lS OF

To face page 358.

Discoidea c)·lindrica

IN LINCOLNSHIRE.

THE ZONES OF THE LOWER CHALK OF LINCOLNSHIRE.

359

FIG. 6.-Typical profile of the pentagonal form from the lower beds, Hubbard's Valley (No 3). Its base is the same shape as Fig. 5. Height: 2'1 em. Diameter: 3'7 em. It will be observed that though this is the tallest of the pentagonal forms, its elevation is exactly the same as the hemispherical form (Fig. 4) described as of medium elevation, though the diameter of the latter is less. This low-cone profile and pentagonal base is what we mean by the typical pentagonal form, and it is the tallest of the forms with pentagonal base. APPE~DIX.

THE RED CHALK OR

HUNSTANTON LIMESTONE.

We subjoin a list of fossils from the above, indicating additions to the list given by Mr. Hill for the county, by an asterisk. The Red Chalk occurs throughout the Chalk area of Lincolnshire, and we have seen it at Pits No. 37, Welton (near Alford), Candlesby (No. 39), Brinkhill (No. 26), Swaby (No 29, in Valley), Stenigot (No. 28), Donington (No. 14), Red Hill (No.4), Belchford (Nos. 22 and 23), near Hallington (No.3), and in a field exposure north-east of Withcall Station. The best sections are between Donington-on-Bain and Withcall in railway cuttings on the Louth and Lincoln line, where it is seen resting upon the Carstone, and is succeeded by several feet of the Lower Grey Chalk.

'"""blJ"' "" U~ A"a

::::

...

~£cE io ~8:g

e<:

• Scaphanorh)'nchus • Ammonites (UM·toniceras) inflatus, Behmnites minimus, List. * Inoceramus concentricus, Parkinson tenias, Mant, " inflllta, Sow. ..• • Plicatula • " siRtflina, S. Woodw. • Ostrea hip/JDpodium. Nilss, Grypht7!a vesicularis, Lam. Avicula gryphoides, Sow. Terebratula bt/Jlicata. Sow. • carnea, Sow. " capz/lata, d'Arch. semtglobosa, Sow. " * Terebratulina ornata, Roem. * Rhynchonella martini, Mant. ..Rhynchone!la plicat'lis, Sow. * Crania, sp. ... ... . .. * Podoseri: mammiliformis, Duncan * Diastopora Stomatopora * Ventriculztes, sp ...• 'Sponge, sp. *Serpula plana, S. Woodw. umbonata "" sp . .. Dentalium, sp. Cidaris, sp.

.

J. Sow, X X

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X X X X X X X X X X X X

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