London Tertiaries Research Articles

Wave velocity and stiffness measurements of the Crag and Lower London Tertiaries at Sizewell

This paper describes an investigation into the body wave velocity and stiffness characteristics of the foundation soils at the site formerly considered for Sizewell C Nuclear Power Station. Results from both in situ and laboratory tests are presented. In situ measurements comprised shear and compression wave velocities using cross-hole and down-hole techniques, including the velocity of horizontally propagating, horizontally polarized shear waves. Laboratory tests included torsional shear tests on hollow cylindrical samples, triaxial compression and extension tests with local measurements of strain, and resonant column tests. Sample quality and the effects of destructuring are evaluated. The anisotropy of the wave velocity and of the stiffness characteristics is highlighted. L'article décrit des recherches sur la vitesse de propagation des ondes de volume et les caractéristiques de rigidité des sols d'assise de l'emplacement proposé de la centrale nucléaire Sizewell C. Il présente les résultats des essais sur place et en laboratoire. Les mesures sur place ont compris la vitesse de propagation des ondes de cisaillement et de compression à l'aide de techniques de forage transversal et descendant, y compris la vitesse de propagation d'ondes de cisaillement horizontales à polarisation horizontale. Les essais en laboratoire ont compris des essais de cisaillement par torsion sur des éprouvettes cylindriques creuses, des essais de compression triaxiale et des essais d'extension, avec la mesure locale des contraintes et des essais de compression de colonne résonante. L'article examine la qualité des échantillons et les effets de la destructuration et met en relief l'anisotropie de la vitesse de propagation des ondes et des caractéristiques de rigidité.

Some coastal changes between Whitstable and Reculver, Kent

The Whitstable-Reculver coast owes much of its scenery to successive landslips in the London Clay and landslides in the Lower London Tertiaries. Its differential recession is found to tie in with the localisation of landslips and landslides in time and in place. Further examination of their link reveals that the relationship between marine erosion and coastal mass movements is reciprocal. The coast subjected to these processes has been modified in a manner which has not always been emphasised.

A section in the Lower London Tertiaries in Ballards Way, Croydon, surrey: Weald Research Committee Report, No. 33

A section in the Lower London Tertiaries in Ballards Way, Croydon, surrey: Weald Research Committee Report, No. 33

A new section in the lower London tertiaries near West Wickham, Kent

A new section in the lower London tertiaries near West Wickham, Kent

A new section in the Lower London Tertiaries near West Wickham, Kent

A new section in the Lower London Tertiaries near West Wickham, Kent

The Mechanical Composition of the London Tertiaries in the neighbourhood of Harrow-on-the-Hill

There have been in the past few years opportunities, which are not likely to recur, for collecting fresh and unweathered samples of the Upper and Lower members of the LondonTertiary series in the neighbourhood of Harrow. It therefore seemed to be worth while making a series of mechanical analyses of these samples for comparison with analyses which have been made of samples from the same formations in the other parts of the London basin.

On the Quartzite Pebbles of the Oldhaven (Blackheath), Beds of the Southern Part of the London Basin

IT is common knowledge to all geologists interested in the Lower Eocenes of the southern part of the London Basin that, in the Oldhaven (Blackheath) Pebble Beds, pebbles of a brown quartzite are often to be found on searching amongst the rounded flints of which these beds are so largely composed. When geological parties visit sections exposing the pebble-beds of the Lower London Tertiaries, the search for these quartzites usually constitutes one of the items of the field-work to be done. A considerable number of these pebbles must, by this time, have been collected but, although their occurrence has given rise to a good deal of discussion and speculation, nobody appears, so far, to have undertaken a systematic examination of their characters and petrological affinities. The view has been propounded that the study of these pebbles would throw light on the question of the source of the material composing the Lower London Tertiary beds.

The Section at Worms Heath (Surrey). With Remarks on Tertiary Pebble-Beds and on Clay-with-Flints

I. History and Literature of the Worms-Heath Outlier The occurrence of outliers of the Lower London Tertiaries far away from the main mass, in the Chalk-tract of Surrey, was known to Prestwich, and the sites of some of them were noted by him, though not in his papers read to the Society. 1 But, presumably because he was then dealing with distance from the main mass and not with size, these sites included only small patches, at the top of the Chalk-escarpment of the North Downs and not the much larger outlier with which we are especially concerned, roughly a square mile in area and some way inward from the Chalk-escarpment. All these outliers consist wholly of the uppermost of the three divisions of the Lower London Tertiaries, to which the name Blackheath Beds has been given, the underlying Woolwich Beds and Thanet Beds being absent. This was not mentioned by Prestwich, who was dealing with the Lower London Tertiaries as a whole and not with the divisions thereof, the details of which, moreover, had not been then fully worked out, his third paper on the Series not appearing until 1854. The first recognition of the Tertiary tract of Worms Heath was on Sheet 6 of the Geological Survey Map, published in 1864, though the Surveyor (who need not be named) was mistaken as to the age of the deposit when he first saw the place, some years before that date, the pebble-beds being taken as a peculiar kind of Drift,

V.—On a Recent Legal Decision, of Importance in Connection with Water Supply from Wells

About, or nearly, forty years ago, two deep wells (with borings) were made at Brentford, which, passing through Gravel, London Clay, and the Lower London Tertiaries, reached the Chalk at a depth of about 315 feet, and were carried some way into the last.One of these wells is at the Brewery on the southern side of the High Street, now known as the Royal Brewery, and it continued in use till its water became unfit for brewing-purposes, from the cause noted below. The other is 99 yards off, north-eastward, at some printing-works at the back of the houses on the other side of the street. This one was made for a Distillery which has long ceased to exist; the well too having been abandoned, at least for its original purpose of water-supply.

On the Lower Eocene Section between Reculvers and Herne Bay, and on some Modifications in the Classification of the Lower London Tertiaries

The Lower London Tertiaries were defined by Prestwich, as consisting of three divisions. Two of these were relatively homogeneous in composition; but the third was made up of very varied materials. The extreme care and accuracy with which these divisions were traced out over the whole of the Eocene area in England, and subsequently correlated with those of the French area, led to their speedy and universal recognition. No modifications in this classification were even suggested until 1866, when Mr. Whitaker, while unreservedly adopting Prestwich's divisions of “Thanet Beds” and “Woolwich and Reading Beds,” making, indeed, copious use of his observations, separated portions of his “basement-bed” of the London clay, where this was assigned any considerable thickness, together with a small portion of his Woolwieh and Reading beds, as “Oldhaven Beds,” and thus almost restricted the “basement-bed” to the inconsiderable thickness of coarser material which nearly everywhere forms the base of the London Clay. Almost the only criticism that can be urged against Prestwich's classification is that he places the “basement-bed” of the London Clay in a different group of the Eocenes from the London Clay itself, his nomenclature implying a closer relationship than he admits. But the Survey, on the other hand, have unfortunately adopted a name ( “Oldhaven ”) which not only does not exist on the maps, but is scarcely known at the locality, an inquiry for “Oldhaven Gap,” where the beds are typically developed, being useless even at the gap

On a section of the Lower London Tertiaries at Park Hill, Croydon

On a section of the Lower London Tertiaries at Park Hill, Croydon

On the Occurrence of Thanet Beds and of Crag at Sudbury, Suffolk

I. Thanet Beds. The newer Tertiary deposits of the Eastern Counties have had such a power of fascination over geologists that the older beds have been left almost unnoticed: indeed since the description of a few sections in Mr. Prestwich's essays on the Lower London Tertiaries, which have now been published 20 years and more, I know of but one paper (and this probably known to very few geologists)* that gives us any information about that series in the district in question, whereas the number of papers that treat of Crag and Drift is legion. It has therefore been an agreeable surprise to me to find, in the course of my Geological Survey work, that there are fine sections of the older Tertiary beds in Suffolk and the neighbouring part of Essex; and it was with some astonishment that I saw one of the finest sets of sections in the London Basin round the town of Sudbury, on the border of those two counties. These sections convinced me that the lowest member of the Lower London Tertiaries, the Thanet Beds, crops out along part of the northern edge of the Tertiary district, an occurrence of which I had a very slight suspicion from other sections near Ipswich. Mr. Prestwich has, indeed, doubtfully referred some of the sands of the northern outcrop to this division, though without describing any section; but he does not notice the particular part where it is now to be seen in many large and clear pits,

On the “Lower London Tertiaries” of Kent

From what has been said above, and from a study of the sections in Plate XXII., we may gather the following facts amongst others:— 1. That the base-bed ( a ) is the only constant part of the Thanet Beds. 2. That the higher and fossil-bearing parts of that series ( d, e ) occur only in the east, which partly explains why it is often very hard to separate the Thanet Beds from the overlying series in the eastern part of Kent, whilst the division is well-marked westward; and that the unfossiliferous sand ( c ) thins out on the east, so that the Thanet Beds near Canterbury may be a different thing from the Thanet Beds between London and Rochester. 3. That the bottom-bed (1) is also constant, except in the far east. 4. That above this last there is always a sand (2), a pebble-bed (2 a ), or a mottled clay (2 b ), which replace one another. 5. That one very thin bed (3) in the middle of the Woolwich Series seems to occur right through Kent, at all events through the eastern division. 6. That the higher and estuarine members (4, 5) of the same series occur only in the western and central parts of the county. 7. That the pebbles (β) at the bottom of the Oldhaven Beds (except at Upnor, where there is a little sand (α) below) are constant, being, however, locally replaced by brown iron-ore in some places near Canterbury. 8. That in West Kent this series lies irregular on that below, whilst in the

On the Sections of Strata exposed in the Excavations for the South High-Level Sewer at Dulwich; with Notices of the Fossils found there and at Peckham

In the autumn of 1859, open cuttings were made at Peckham, in connexion with the “Effra branch of the Great South High-level Sewer,” for the “main drainage” of the metropolis south of the Thames; and in the following spring a tunnel (330 yards in length) was being constructed under the Five-fields at Dulwich. The beds exposed in both sections belong to the “Woolwich and Reading Series” of the Lower London Tertiaries (Prestwich). Four shafts were sunk to facilitate the driving of the tunnel; and the following beds were exposed; but, as some of the beds are not persistent, but die out even within the extent of the tunnel, the several shafts differed as to the sections obtained from them.

Notice of the Fossil Remains of a New Fresh-Water Mollusc from the Lower London Tertiaries

In making the excavations now in progress for the formation of the great South High Level Sewer in the neighbourhood of Peck-ham and Dulwich, the works have been carried through a series of deposits, constituting part of the lower London, Tertiaries, and distinguished by Mr. Prestwich as the “Woolwich and Reading series.” As I learn from Mr. Charles Rickman, the able and zealous curator of the Lambeth Museum of Natural. History who has laboured assiduously in collecting the fossil remains found in them, these deposit at Dulwich, at the depth of twenty-five feet from the surface, comprise a bed of grey sand, and below this, at a depth of about forty feet, and intercalating a bed of clay containing, shells and a bed of Ostreæ, a band of hard compact sandstone, very slightly calcareous, apparently identical with that at Lee, referred to by Mr. De la Condsmine as known there by the name of the “cookle.”

The Oyster Conglomerate Bed at Bromley, in Kent

There are many localities around London which possess features of interest to the geologist, that can be reached and examined on a single day. Such a one is the pretty little town of Bromley, in Kent, with a population of 4,000 souls, at a distance of ten miles from London Bridge, and now within easy reach by the Mid Kent Railway, only just opened. A mile to the north-east of Bromley is Sunderidge Park, in which is to be seen a section of the well-known oyster-conglomerato rock, in a large pit which, together with the accompanying shingle, has been quarried for various purposes for many years. This spot is noticed by Dr. Mantell in his charming volumes, as one of the most interesting localities he was acquainted with. At and around Bromley is an area of some extent, formed by the Lower London Tertiaries; a small patch of chalk, however, crops out to the east of the town, in which are some ancient quarries. One of these possesses some interest from being underground, and containing, as I was informed, several intricate windings.The London clay, with the underlying plastic or Woolwich clays, and Tnanet sands, constitute the lower division of the Eocene strata of the Tertiary group of rocks. The London clay extends over several counties of England, constituting a large part of the soil of Essex, nearly the whole of Middlesex, and portions of Berkshire, Surrey, and Kent.

On the Correlation of the Eocene Tertiaries of England, France, and Belgium

If the synchronism of the Bracklesham series with that of the “Calcaire grossier” be admitted, then the independence of the London Tertiaries with respect to the former deposit will apply with equal force to the latter. For I have lately shown that the London series contains 485 species of organic remains (plants excluded), and that only eighty-eight or 18 percent, of these pass upwards into (or through) the Bracklesham series; or taking the fossils of the two series together, there are only 9·4 per cent. common to both. There are altogether 397 species peculiar to the London group, and they form—the Fishes, Reptiles, Crustaceans, and Echinodermata especially—a very characteristic fauna. The distinctiveness of age and origin shown by the fauna is fully corroborated by the physical evidence. The large proportion of species peculiar to the three lower divisions of M. d'Archiac also shows a well-maintained distinction between these beds and the Calcaire grossier; although in this case the fauna of the Lits Coquilliers serves as an intermediate link, and tends to lessen the apparent force of that difference. Nevertheless, these lowest French divisions are evidently in closer relation with our more distant London Tertiaries than with the overlying series in the Paris area. I conceive, therefore, that we may take the “London Tertiaries” as a good natural group, constituting an important and independent division of the Eocene period perfectly well marked by its organic remains. In this country it is equally well distinguished by structure and physical characters ; whereas

On a Fossiliferous Deposit in the Gravel at West Hackney

I n the summer of 1853, Dr. Beeke informed me of the discovery of some large mammalian bones in a gravel-pit belonging to Mr. Hindle, at Shacklewell Lane, between Hackney and Stoke Newington. In company with the former of these gentlemen, I visited the spot, which is 60 feet above the level of Trinity high-water mark, on several occasions, and found many points which I deem of sufficient interest to lay before the Society. I found that the bones were not actually in the gravel, but in a bed of clay between two beds of gravel,—which clay forms a distinct and separate deposit with an abundance of freshwater and land shells. The occurrence of the bones was an exceptional case, no other bones having been previously met with at this pit, though common at some others in the neighbourhood. The following is a sketch of part of the pit :- No fossils have been found in the brick-earth ( a ) of this district. The gravel ( b ) is spread out in large sheets which produce an appearance of rough stratification; it consists of subangular broken flints, with some very large nearly whole flints hardly at all worn, flint-pebbles from the Lower London Tertiaries, a few quartz and sandstone pebbles, and some rolled pieces of very. hard, compact, siliceous sandstone. Only a few feet square of the underlying clay ( c ) was uncovered. The line of separation between these two beds is merely slightly waved, except at one spot, where the gravel lay in an

On some Minute Seed-vessels ( Carpolithes ovulum Brongniart), from the Eocene beds of Lewisham

O f this remarkable and beautiful little fossil three or four specimens have been detected in the Eocene clays of Lewisham, by the late Rev. H. de la Condamine, and one of them in so perfect a state that I have had little difficulty in making out the details of its structure. They occurred associated with freshwater shells in the “ Planorbis bed” at Counter Hill, and are alluded to in Mr. Prestwich's valuable memoir on the “Woolwich and Reading Series” of the London Tertiaries, Quart. Journ. Geol. Soc. vol. x. pp. 119 and 156 (see also Pl. 3. fig. 4). A few other vegetable remains were found associated in the same bed with this Carpolithes , but none that throw any light upon its affinities. Amongst these are two kinds of Dicotyledonous leaves, together with the pinnm of a Fern not differing in venation from the existing genus Asplenium *, and the remains of Monocotyledonous leaves. To the same formation, however, Mr. Prestwich has referred some fragments of couiferous and other Dicotyledonous woods, and a Fir-cone, referable apparently to the existing genus Abies†. Dr. Mantell also, in his ‘Geology of Sussex,’ has figured some vegetable remains alluded to by Mr. Prestwich as apparently agreeing with some of the Reading species, of which latter a beautiful series of forms, chiefly of leaves of Dicotyledonous trees, are given at P1. 4 accompanying the Memoir before mentioned‡. The whole assemblage appears to indicate that the climate of the period during which they flourished did not materially

On the Correlation of the Lower Tertiaries of England with those of France and Belgium

Abstract I n this paper Mr. Prestwich treated of those Tertiary beds which, commencing immediately above the Chalk, are in England limited superiorly by the Bracklesham Sands; in France, by the Calcaire grossier , and in Belguim, by tne Système Bruxellien of Mr. Dumont; and he endeavoured to show the exact correlation of the several divisions of these lower tertiaries, and claimed for the “London Tertiaries,” as a group, a distinct and separate position beneath that of the Paris group, of which latter the Calcaire grossier may he taken as the centre and type. The chief points of importance are—that the Lower Bagshots are the equivalents of the Lits coquilliers ; and that the well-known Sable de Bracheux , with its marine fossils, corresponds with the lower part of the Woolwich series. The author first pointed out that the known equivalents among the Tertiary beds in question are— 1. Calcaire grossier, France = Bracklesham Sands, England = Système Bruxellien, Belgium. 2. Lits coquilliers, France = Syst. Ypresien supérieur, Belgium. (The zone of Nummulites planulatus.) 3. Lignites of the Soissonnais = Fluviatile beds of Woolwich and Lewisham. Mr. Prestwich then described in detail the grouping of the tertiary strata in France, Belgium, and England respectively; and, having pointed out the local differences and peculiarities exhibited by these deposits, he entered upon a detailed comparison of the different divisions of the tertiaries of the several districts.