MEMOIRS OF THE GEOLOGICAL SURVEY. ENGLAND AND WALES. SOILS AND SUBSOILS FROM A SANITARY POINT OF VIEW; WITH ESPECIAL REFEREj LONDON AND ITS NET By HORACE B. WOODWA SECOND EDITION. PUBLISHED BY ORDER OF THE LORDS COMMISSIONERS OP HIS MAJESTY'S TBEASITRT. LONDON: PRINTED FOR HIS MAJESTY'S STATIONERY OFFICE, By WYMAN & SONS, Limited, Fetter Lane, E.G. And lo be purchased from E. STANFORD, 12, 13 and 14, Long Acre, London ; JOHN MENZIES & CO., Rose Street, Edinburgh ; HODGES, FIGGIS & CO., Grafton Street, Dublin ; From any Agent for the sale of Ordnance Survey Maps ; or through any Bookseller from the Ordnance Survey Ofiice, Southamiiton. 1906. Price Is. 6d. LIST OF MAPS, SECTIONS, AND MEMOIRS OF THE GEOLOGICil SURVEY OF ENGLAND AND WALES, AND MUSEUM OF ' PRACTICAL GEOLOGY. 1 J. J. H. Teall, M.A., D.Sc, F.R.S., Director of the Geological Survey and Museum, Jermyn Street, London, S.^ The Maps and Memoirs are now issued by the Ordnance Survey. They can be obtained from Agents or direct tt the Ordnance Survey Office, Southampton. Museum Catalogues, Guides, &c., are sold at the Museum, 28, Jern) Street, London. A Complete List of the Publications can be obtained from the Ordnance Survey Office, Southampton, Price Is. GENERAL MAP (one inch to 4 miles). ENGLAND AND WALES— Sheet 1 (Title) ; 2 (Northumberland, &c.) ; 3 (Index of Colours) ; 4 (I. of Man) ; 5 (Li District) ; 6 (E. Yorksliire) ; 7 (North Wales) ; 8 (Central England) ; 9 (Eastern Counties) ; 10 (South Wales t N. Devon) ; 11 (W. of England and S.B. Wales) ; 12 (London Basin and Weald) ; 13 (CornwaU, . f London Clay 5 Blackheath Beds ■^ j Woolwich and Reading Beds ^ llhanet Sand ,Ghalk .... § Upper Greensand Gault Lower Greensand Weald Clay i Hastings Beds - Clay. - Gravel and sand. . Clay, shelly marl, sand,ai,nd gravel. - Sand. - Soft white limestone, with bands and nodules of flint ; and nuxrl. - Sandstone and sa7id. - Clay. - Sand and sandstone, with lime- stone, chert, and clay. - Clay. - Sand, sandstone, and clay. Geological Maps and Models. The little map which accompanies this work will be useful a? an index to the general distribution of the subsoils in the area around London. The Geological Survey has also published a colour-printed one- inch map of the London District in four sheets : — No. 1 includes Rickmansworth, Barnet, Uxbridgc, and N.W. London. No. 2 includes Enfield, part of Brentwood, Upminster, and N.E. London. No. 3 includes Staines, Chertsey, Sutton, and S.W. London. fill this map the areas coloured Woolwich and Reading Beds beyond the main outcrop at Sutton, should have teen coloured London Clay.] No. 4 includes Purfleet, Farningham, Croydon, and S.E. London. Maps on the scale of six inches to a mile arc, however, necessary for all practical purposes. All the recent work of the Geological Survey has been carried out on these large-scale maps, MS. copies of which are preserved at the Ofl&ce ; but at present only a portion of London and of the country around has been surveyed geologi- cally on a scale larger than that of one inch to a mile. The following is a list of the MS. cojjies of Geological six-inch maps of the London District (see Index-map, p. 70) : — Middlesex. U N.E. Uxbridge. 2 S.W. Enfield Chase. S.E. West Drayton. 5 N.E. Bushey, Herts. 15 N.W. (5 L.) Yeading. S.W. Pinner Hill. N.E. Greenford. S.E. Stanmore. S.W. Hayes and Southall. 6 S.W. Edgware. S.E. Ealing and Hanwell. 7 N.E. (1 L.) Enfield. 16 N.W. (.6 L.) Willesden. S.W. Southgate. N.E. Kilburn. S.E. Edmonton. S.W. Acton. 9 N.E. Harefield. S.E. Kensington. S.E. Ickenham. 18 N.E. (8 L.) Bow. 10 N.W. Pinner. 19 N.W. Colnbrook End. N.E. Wealdstone. N.E. Harmondsworth. S.E. Harrow. S.W. Wyrardisbury, Bucks. 11 N.W. (2 L.) Kingsbury. S.E. Stanwell. N.E. Hendon and Finchley. 20 N.W. (9 L. : Cranford, Heston S.W. Neasden and Wembley. N.E. Brentford, Hounslow. S.E. Hampstead. S.W. Feltham. 12 S.E. (3 L.) Stoke Newington. S.E. Twickenham. GEOLOGICAL MAPS AND MODELS. Middlesex. Essex. 74 N.W. Ghadwell Heath. 24 N.W. Egham, Staines. N.E. Becontree Heath. I^l.E. Staines, Laleham. S.W. Barking Level. S.E. Shepperton. S.E. Dagenham. 25 N.W. (13 L.) Hanworth. 75 N.W. Upminster. N.E. Teddington. N.E. East Horndon. S.W. Sunbury. S.W. Gorbets Tye. S.E. Hampton Court. S.E. South Ockendon. 82 N.E. Rainham Marsh. Surrey. 83 N.W. Aveley. 1 S.E. (9 L.) Kew. N.E. StifEord. 2 S.W. (10 L.) Mortlake. S.W. Purfleet. S.E. Battersea. S.E. Grays. 6 N.E. Richmond, Petersham. S.E. Kingston -on -Thames. Bucks. 7 N.W. Putney Heath. 53 N.E. Pulmer. S.E. Tootins. S.E. Iver. 11 N.W. Chertsey. 56 N.E. Langley. Essex. London. 6G S.W. Hainault Forest. 4 N.W. Woodford. S.E. Romford. S.W. Wanstead. 67 S.W. Great Warley Street. S.E. Jlford. S.E. little Warley. 8 N.E. Barking. Those marked L. are London County maps. Reference may here be made to the Geological Model of London (scale, six inches to a mile) prepared imder the superintendence of Mr. W. Whitaker and placed in the Musemn of Practical Gleology. A smaller Geological Model of London and Suburbs, on the scale of one inch to a mile, prepared by Mr. J. B. Jordan, and published by Mr. E. Stanford, is also exhibited in the Museum. Further particulars of the geology of the district will be foimd in Mr. Whitaker's " Guide to the Geology of London,'- ed. 6, 1901, price Is. ; and in his " Geology of London and of Part of the Thames Valley,'- 2 vols., 1889. price lis., issued by the Geological Survey. Separate ^Memoirs have also been i.ssued on " The Water Supply of Berkshire from Underground Sources," by the late J. H. Blake, with contributions by Mr. Whitaker, 1902, price 3s. ; and on " The Water Supply of Sussex from Underground Sources," by Mr. Whitaker and Mr. C. Reid, 1899, price 3s. CHAPTER II. SOILS AND SUBSOILS OF LONDON AND ITS NEIGHBOURHOOD. SOILS. Made Ground. The surface-soil of London, and also of many other large cities and towns, is a mixture of mould, gravel, or clay, with debris of ancient builiings and rubbish. Much of this has been upturned over and over again, so that it comprises an accumulation of brick- bats,, fragments of crockery, and what not, commingled with relics of the soil and subsoil. In a few localities in London it has accu- mulated steadily, or at irregular intervals, at the rate of from 6 inches to 1 foot a century. Portions of the "Made Ground " are thus of ancient date, and in these undisturbed areas it has preserved trophies of the Roman occupation, of the Great Fire, and other in- teresting episodes. (See Fig. 3.) Fig. 3.- ' Section in Cannon Street. (W. Chaffers.)* ::^m-^^^^ Made Ground Oft. Valley Drift. A. Level of the street. B. Roadway before the Great Fire of London, in 1666. G. Earth in which Norman and Early English Pottery is found. ^ D. Eoman tesselated pavement. I E. Black soil in which red lustrous (Samian) and other Roman \ ware is found. (F. Loam. )^ \G. Gravel, j 3 ft. * F. W. Rudler'B " Handbook to Collection of British Pottery and Porce- lain,'! 1893, p. 67 ; Whitaker, " Geology of London," Geol. Survey, vol.ii , 1889, p. 324. See also A. Tylor, Arckceologia, vol. xlviii., 1885, p. 222. 10 MADE GROUND. Made Ground may be from a foot to about 25 feet in thickness, the greater thicknesses being here and there due to the in-filHng of old pits. Excavations at London Wall showed the following section :* — Feet. Made ground about 8 Dark carbonaceous clay with freshwater shells and traces of vivianite about 10 Thin bed of broken bones — Gravel about 10 London Clay At the Bank of England there were 22 feet of Made Ground, resting on four feet of gravel, over London Clay. In describing the excavations on the site of the New Law Courts, Mr. W. H. Hud- leston and Mr. F. G. Hilton Price drew attention to the extreme irregularity in the junction between the Made Soil (brick-rubbish, etc.), and the imderlying gravels : thus " Many an old foimdation may be seen projecting like a promontory into the subjacent sandy gravels, and, where these thin out, into the London Clay itself. The numerous old wells also tend to confusion in this respect."t At the corner of St. James' Square and King Street, the Made Ground was 10 feet thick, and sand was proved to a depth of 16 feet beneath it. Such artificial " Soil " of varying character and thickness, no doubt extends over the whole of old London. Mr. Whitaker has remarked that Belgravia is probably in great part built on groimd of this nature, otherwise it would be lower and damper. In itself Made Ground is not always an unsatisfactory foundation for a house. Much of it, as stated, is of ancient date. Moreover good material may artifically be brought to level an irregular tract. The serious matter is that in these enlightened days it has been possible for houses to be erected on pits in which all kinds of rub- bish, with decaying vegetable and animal matter, had recently been shot. As Sir Douglas Galton remarked, " What then can be more dangerous, what more wicked, than the everyday proceedings in the metropolis and elsewhere, of those persons who purchase a building site, who extract from it the healthy clean gravel and sand which it contains, allow the hole to be filled with rubbish, and then proceed to build upon it ? "J It is well known that in- jurious emanations come from an impure soil or subsoil, and may rise into a house ; so that on such an unwholesome foundation it is absolutely necessary that the basement be securely cemented. The law should now prevent any further building of houses on polluted sites. ♦ E. A. Martin, " Science Gossip," ser. 2., vii., 1901, p. 319. t Proc Oeol. Assoc, vol. iii., 1872, p. 44. t Trans. Sanit. Inst., vol. i., 1880, 120. NATURAL SOIL. 11 Natural Soil. The natural soil is of varied composition, being primarily de- rived from the subsoil, which may be regarded as the weathered portion of the underlying hard or soft strata. With the decom- posed mineral ingredients of the subsoil is mingled more or less decayed animal and vegetable matter ; while the whole soil-layer has been largely re-constituted by the action of earth-worms and micro-organisms, by plant-growth, and processes of cultivation. To the work of worms, as pointed out by Darwin, is due the fine surface-layer of mould, which is rich in vegetable matter ; and as stated by Mr. A. D. Hall, the term humus " is applied to the black or dark brown material of vegetable origin which gives to surface soil its characteristic darker colour as compared with the subsoil. It is essentially a product of bacterial action."* Wind -drifted material has also to some extent modified the constituents of soil. As a rule, the natural soil is too thin to have any particular effect on the sanitary conditions of a site, although in places it may be as much as 3 feet or more in thickness. It is thicker on the lower slopes of hills and in valleys, owing to its downwash by rain from the higher grounds. It is usually thicker also on the gravelly, sandy and loamy areas than on the stiff clays or on the Chalk, f With regard to micro-organisms (bacteria), which aie found in soils, it is satisfactory to know that " the dangerous microbes are in a hopeless minority in comparison with the number of those which are continually performing varied and most useful functions in the economy of nature." Moreover the surface-layers of the soil harbour the vast majority of the bacteria ; they lessen in number in the deeper layers, and few or none are to be met with in the subsoil at a depth of 8 or 10 feet. Their number lessens when the surface-soil is moist, and increases as it dries. :|: Certain pathogenic organisms, however, appear to flourish at a depth of 4 feet in the soil, when its temperature is above 56°. § SUBSOILS. Alluvimn or Marshland. The low-lying tracts that immediately border the Thames and its tributaries, and that fringe the lower courses of most rivers, should be regarded as essentially the property of the river. * "The Soil,'! 1903, pp. 14, 41. See also G. Reid, "Dust and Soils," Geol. Mag. 1884, p. 165. t For remarks on the influence of the colour of soil on temperature, see Dr. H. R. Mill, Trans. San't. Inst, vol. xv., 1895, p. 174 ; H. A. Roechling, " Geology in Relation to Health,'- Trans. Leicester Lit. and Fhil. Sue, vol. v., 1900, p. 347. X Dr. AUanMacf adyen ( Discourse at Royal Inst. ) Nature, Feb. 7 th , 1 901 , p. 359. f^''§ Dr. S. M. Gopeman, Trans. Sanit. Inst., vol. xvii., 1897, p. 37. Bacteria are microscopic forms of plant-life, and they include rod or chain-hke forms (bacilli), and grains (cocci). 12 ALLUVIUM OR MARSHLAND. Originally marshlands, they sometimes remain so, and at any rate they are liable to be flooded when the river is so swollen as to overflow its natural banks. Artificial ramparts may preserve these tracts as meadow-lands, but they are to be avoided as sites for residences; and it is noteworthy that they were not chosen by the early settlers. Composed of silt and clay with peat and occasional layers of marl or gravel, these beds vary in thickness from 5 to 40 feet, and form a damp and unreliable foundation. Gravel usually underlies the Alluvium, and this is often waterlogged, so that if the river be in flood and the Alluvium be thin or porous, water may rise in the cellars of houses built upon such low-lying ground. Basements of houses erected on river-flats are in any case liable to be damp, and their construction in such situations is undesir- able : if, however, it cannot be avoided, the houses should be constructed with impervious walls and floors. Permanent injury may be done to buildings if in more open country such sites are chosen, and the river occasionally asserts its rights by flooding the tract. In wet weather sheets of water may cover areas of Allu- vium for some length of time. Fortunately there are but small areas of Alluvium in the heart of London ; there are tracts at Walbrook and Pimlico, and also at Lambeth, Bermondsey, Rotherhithe, Deptford, and the Isle of Dogs. After long -continued rains, and with an East-North-East wind accompanied by high-tide, the Thames sometimes rises so as to flood the lowest parts of Wapping, Deptford and Rotherhithe, of Southwark, Lambeth, and Vauxhall. In consequence of a gale which changed during the night of November 28th, 1897, from South-West to North-West, there was an immense influx of water into the Thames from the North Sea, the river rising 6 feet higher than usual. The wharves at Woolwich Arsenal and the Royal Dockyard were flooded, so also were Tilbury Marshes and the lower part of Grays. On the following evening the river rose 3 or 4 inches above the level of the Embankment footway near the Temple.* In certain locaUties a protective covering of Made Ground, 4 to 6 feet thick, renders the old marshland habitable, as at Pimlico. There the Alluvium itself is from 6 to 30 feet in thickness, the deeper portion being nearer the river. At the Grosvenor Hotel the following superficial strata were proved : — Ft. In, Made ground - - 4 Mud - - 4 9 Peat - - - - 3 3 Glay - ... 2 Peat --10 S««id and gravel - -90 24 * Daily News, December 30th. 1897. ALLUVIUM OR MARSHLAND. 13 Westminster is thus situated on old marshland, part of the area being formerly the island known as Thorney.* A tract of Alluvium occurs along the Colne valley from Wat- ford, widening out through the lower part of Rickmansworth, and extending by Uxbridge to Staines. On Staines Moor and by Runny - mede (Runemede) the ground contains much peat, and has been subject to floods. Below Staines the high road to Chertsey and the Alluvium onwards to the tributary valley of the Wey, likewise the low grounds bordering the Mole, between Hersham and Thames Ditton, are liable to floods. Along the Brent valley between Greenford and Hanwell, the Alluvium consists largely of re -deposited London clay, with seams of gravel, and the tract of flat meadow -land is subject to floods. There is a broad tract of Alluvium along the Lea valley, forming the marshes of Enfield, Tottenham, Walthamstow, Hackney, and West Ham ; and a similar tract extends along the northern side of the Thames in the Levels of Plaistow, East Ham, and Barking, and the marshes of Dagenham, Rainham, Grays and Tilbury. Severe floods sometimes occur in the Lea valley, and cause injury to the market -gardens in the low grounds. The Walthamstow, Hackney and Stratford marshes are occasionally covered by two or three feet of water, and flood- waters may occupy the flats by Wal- tham Cross, Cheshunt, and Chingford. The valley of the Roding at Ilford is also liable to floods. On the southern side of the river there are the marshes of Green- wich and Plumstead, areas which are embanked ; but the base- ments of houses at Lower Charlton and elsewhere along their borders have at rare intervals been flooded. In places these low-lying tracts, some of which are below the level of high-water mark, have been utilized in the construction of Docks. Elsewhere gas-works, chemical factories, candle and soap-works have been established. There are indeed growing populations on the East Ham and Plaistow Levels, as at Canning Town, Beckton, Silvertown, and North Woolwich ; but while the necessities of livelihood or calling require residence in them, such areas are in general undesirable, though I have been assured that Beckton is not unhealthy. Possibly the disinfecting influence of the gas-works may contribute to the salubrity, while the currents of air that follow the course of the river are no doubt beneficial. Crossness again, with its main drainage -works, is not a locahty which one would naturally choose as a residence, but the best care is taken of those who are obliged to seek a habitation near the works. (S:e Fig. 4.) * See W. J. Loftie, " History of London," 1883, vol. ii.. p. 34. 14 ALLUVIT^M OR MARSHLAND. t»o '■'''• o^-- ■> w O o V s o PP o • — ® O 02 Ph O eg a o o Hi = el II '^ pq s fl ; • « o',., '• i-«.a i-o '° 00 i«-i> e •'«''•<>' « ?> I3i .. .A* M OQ fit O Ph ■^ CO 00 O C hO o '^ la o ^ 'i^i! ^ C5 ^1 VALLEY GRAVEL. 15 One of the most serious objections to any large population on alluvial grounds, as pointed out to me by Mr. F. J. Bennett, is the difficulty of introducing any eSective system of house -drainage, owing to the want of all to carry away the sewage. This, how- ever, applies to low-lying ground in general. Another difficulty may be the water-supply, as at Rainham Ferry, on the Essex marshes, where in the absence of a deep well "' the inhabitants are entirely dependent for their supply on rain water and on condensed water from the manufactories."* Gravel, Sand and Sandstone. Valley Gravel. The Valley gravel and loam (brickearth) are ancient alluvial deposits of the Thames and its tributaries, occupying tracts above the level of the marshland, and indeed rising to elevations of 140 to 180 feet and more along the Colne valley, at Denham and south- west of Rickmansworth ; and to about 150 feet at Highbury. The loam (see p. 29) occurs irregularly in and over the gravel. The gravel is most largely composed of flint in the form of subangular stones and pebbles, together with quartz and quartzite pebbles. It contains much sand in places, and occasionally peaty layers occur. Both sand and gravel are locally blackened by oxide of manganese. The greater part of old London and the villages now incorporated in modern London were built on the valley gravel. Naturally these tracts include some of the better residential sites in London and the vicinity ; but it must be remembered that they vary a good deal in elevation, some being but a few feet above the Alluvium, and that the sanitary condition of the ground largely depends on the situation and thickness of the gravel. In low-lying areas especially, where there are broad tracts of gravel, the subsoil is likely to contain much water, and the basements of houses are apt to be damp. This is the case sometimes at higher elevations where the gravel is thin or where it lies in a sort of basin, and where living-rooms are constructed partially beneath the surface. The larger portion of the broad valley of the Thames from Great Marlow to Maidenhead and Taplow, Windsor, Eton, Colnbrook, Staines and Chertsey, eastwards to Hounslow, Twickenham and Teddington, is occupied by valley gravel and sand, with here and there areas of loam. Mixed areas of gravel and loam occur in the vicinity of Brentford, Hanwell, Ealing, Acton, and Gunnersbury. Moreover a thin loamy covering which extends over portions of the gravel tracts, has exercised an important and beneficial influence on the soil. This district has in consequence been long celebrated * Report to Loccal Government Board, by E. Evans, 1894. ]() VALLEY GRAVEL. for fruit and vegetables, although many a famous market -garden or nursery-ground has now vanished from neighbourhoods such as Chelsea and Hammersmith, where in old times they flourished.* It has been remarked that the prosperity of London market - gardens is due partly to the proximity of a market, partly to the large amount of stable-manure that could be readily obtained.f With the introduction of motor -vehicles the lack of manure is already being experienced. At the Mount and Castlebar Hill, EaHng, there are tliin patches of gravel resting on London Clay, but the ground is essentially clayey, although here and there it is lightened by the former pres- ence of gravel and sand, of which relics are preserved in the soil.J On the southern side of the river, Mitcham and other localities have also furnished market-gardens, and grounds formerly cele- brated for the cultivation of lavender, camomile, peppermint, and other medical herbs. The cultivation of lavender, &c., is now carried on further south, mainly on chalk tracts. Among the residential districts south of the Thames, Egham, Chertsey, Addlestone. and Byfleet, Walton-on-Thames, Hersham, Molesey, and Thames Ditton are situated on valley gravel, so also are the lower parts of Richmond, Kew, Mortlake, and Putney. Near the Thames in these, as in other similar localities, the gravel is especially liable to contain a good deal of subsoil-water, and basements of houses may be damp. This would be the case after long-continued rain, when, as sometimes happens, the river rises so high that theislands near Twickenham, Kichmond, and Isle- worth are covered with water, while the low grounds bordering the river from Kingston to Barnes and Chiswick may be inundated. Under such conditions cellars are sometimes partially flooded, for the ground- water naturally rises to the level of the swollen river. When the Thames is in flood the low grounds extending from Eton by Datchet, Wyrardisbury (Wraysbury), and Egham to Staines and Chertsey are not unfrequently under water. (See p. 13.) At Windsor on January 23rd, 1899, the river was 2 feet 8 inches above its summer-level. Further east much of the valley gravel occurs in straggling masses or isolated tracts on the London Clay, so that Roehamp - ton. Putney, Wandsworth, Clapham, Brixton, Tooting, Merton and Raynes Park, Croydon and also Lewisham are partly on gravel and partly on the clay or lower Tertiary strata, the old vil- lages having outgrown the limits of the gravel areas on which they were originally fixed. On the higher and more isolated * There remain the Chelsea Botanic Gardens, now administered for the promotion of the study of Botany, and formerly kno\\n as " The Physick Garden '' of the Society of Apothecaries. t G. V. Poore, " Essays on Rural Hygiene," 1893, p. 317. + S«e J. Allen Brown, Qiinrf, Journ, Geol. Soc, vol, xlii. p. 192. VALLEY GRAVEL. 17 tracts of gravel the sites are drier than in the lower grounds, as the subsoil water more readily escapes in the form of springs. The lower parts of Lewisham have been flooded after long-continued rain, and so also have similar tracts at Mitcham and Merton. North of the Thames the valley gravel extends beneath the greater part of old London, through Stepney, Bow and Hackney, on the east side of the Lea valley from Stratford to West Ham, Barking, Romford, Dagenham and Rainham ; while north-east- wards it stretches to Leyton and Wanstead, and over parts of Walthamstow. In the semi-rural portions of this region there are market-gardens. The lower grounds of Romford have at times suffered from the flooding of the river Rom, which flows through the town. On the western side of the Lea valley there is a belt of valley gravel which occupies the area from Cheshunt by Waltham Cross and Enfield Lock to Ponders End. Islington, with Canonbury, Barnsbury, and parts of Highbury (near the Church) lie on gravel ; so also do Bloomsbury, Maryle- bone, Paddington, Kensington (the older portions), Brompton, and Chelsea. Kensington gravel-pit was situated on the borders of Notting Hill, north-west of Kensington Gardens ; similar gravel may now be seen in the railway-cutting between High Street and Gloucester Road Stations. The gravel and sand often contain much water, and this af- forded in old times a supply to the villages now incorporated in London. In excavations for the new buildings of the Victoria and Albert Museum, about 1000 gallons of water an hour were pumped from the gravel, which was excavated to a depth of 15 feet beneath 5 feet of made soil. During drainage-opera- tions at Highbury, east of Highbury Park and Grove, much water was encountered in the gravel. This ground -water is a cause of dampness to some underground breakfast-rooms. It has been suggested that water from the gravel might be pumped for use in watering roads, &c., but there would be some danger of weakening the foundations of buildings if such a proceeding were generally adopted. The valley gravels and associated loams are from five to about forty feet in thickness. As instances of the variable character of the subsoils, the following sections may be noted * (See also p. 30) :- Maryhbone Road. Feet. West Ham. Feet. Made ground - 9 Made ground - 4^ Loamy gravel - 8 Gravel and clay - 2h Loam - - - 8 Gravel - - IO.t Gravel 33i 17^ * See Whitakcr, " Geology of London,'- 2 vols., 1889. 8574. 18 VALLEY GRAVEL. Fidham. Ppckham. Feet. Fe?t. Made ground - 3-^- Gravel - - 3 Fine sand - 10| Loam and sand - It Sand and gravel - 18 J Gravel - - 3 31i 20 On the southern side of the North Downs, tracts of valley gravel border the Wey and its tributaries at Godalming, Shalford, Guildford, and Wonersh ; the Darent between Westerham, Sundridge and Otford ; and the Medway from Maidstone to Leybourne, Aylesford, and Snodland. To the north of the Downs at Millmead, Guildford, the lower portions of houses have been flooded, and further along the course of the Wey, at Woking village and also at Send, the effects of floods are occasionally experienced. Gravel of Higher Grounds and Plateau Drift. Beds of gravel and sand, occupying as a rule higher levels than the valley gravel, occur in many tracts of the country around London, on the clay- areas of Buckinghamshire, Middlesex, Hert- fordsh're, Essex, Kent and Surrey. Other and more extensive tracts of gravel occur at various elevations on the Chalk betv/een St. Albans and Beaconsfield, and they furnish sites as dry probably as any to be found in the area under consideration. These gravels are from a few feet to about 25 feet in thickness, and rarely as much as fifty feet. They vary in character from pebble-gravel or shingle, largely made up of fljnt and small quartz pebbles, to coarse sub-angular gravel and sand, containing, in addition to flint and quartz, many pebbles of quartzite and other stones. On the clayey area there are patches of gravel in the higher parts of Richmond Park at Kingston Hill, Wimbledon Common and Putney Heath, at Shooter's Hill, over parts of Woodford, Chigwel', Buckhurst Hill, High Beech, and the higher grounds of Epping Forest, near Epping. Again, there are tracts of gravel and sand at Southgate, Colney Hatch, Friern Barnet, Whetstone, Totteridge, High Barnet, Monken Hadley, Ridge^ Shenley, Potter's Bar, and Northaw, at Finchley, Hendon, Stanmore and Bushey Heath, Pinner Hill, Oxhey Wood, Moor Park, Horsendon Hill, Harefield and Hillingdon. Other patches of gravel lie to the south-west between Denham and Fulmer, on Fulmer and Stoke Commons to the north of Stoke Poges, and at Beaconsfield. It is worthy of note that these gravels have sometimes a clayey or loamy matrix, and may then be of a retentive nature. I was told by a gentleman who had taken a house situated on a gravel patch at Totteridge, that liis gardener informed him the soil was GRAVEL OF HIGHER GROUNDS. 19 a " heavy clay." Nevertheless, in excavating for a water-tank, he had dug out several tons of pebbles ! The gravel, in fact, con- sisted of a stiff sandy clay packed with pebbles. There are thin patches of gravel at DoUis Hill, near Neasden, at Highwood Hill, and also at Mill Hill to the south of the King's Head Inn and to the east of Frith Manor House. Sprinklings of gravel occur elsewhere on the liigher clay hills, serving to lighten the soil ; moreover they are found here and there on slopes below the larger patches of gravel. This is notably the case on Stan- more Hill, and again near Brentwood and Warley. At Hendon, as pointed out by Dr. Henry Hicks, there is a thick bed of brown clay intercalated in the gravels, and a similar band locally occurs at Finchley. These are re-assorted masses of brown London Clay, which . have become incorporated vvith the gravel during its accumulation. These plateau gravels form, as a rule, good residential sites, because the subsoil water is to a large extent drained off by springs on their margins. Moreover, they occupy breezy positions. More extensive tracts of gravel and sand occur, as before- mentioned, on the Chalk in Hertfordshire and Buckinghamshire. These comprise certain areas at Hitchin, Stevenage, Welwyn, Hatfield, Sandridge, St. Albans, London Colney, Aldenham, Wat- ford, Chipperfield, Sarratt, Chenies, Chorley Wood, Croxley Green, and the liigher grounds above Rickmansworth, Chalfont St. Peter, and Chalfont St. Giles. Beds of loam and clay are her6 and there intercalated with the gravel and sand. So far as the subsoil is con- cerned the areas may be highly commended ; they are pleasantly situated and picturesque, and only in a few localities where the gravel descends to low grounds bordering the Colne valley above Watford, Avould the sites be liable to damp. As the water in the underlying Chalk is largely drawn upon for drinking-purposes, it is most desirable that the sanitary arrangements in dwelling- houses be so constructed that no pollution of underground water is possible. Here and there patches of gravel occur on the Bagshot Sands, as in Essex and Surrey, and the localities are noted in the descriptions of those sandy areas. Blackheath Beds. These are composed of gravel made up almost entirely of flint- pebbles in a sandy matrix, and often with beds of sand ; but layers are occasionally cemented into a conglomerate. In thick- ness the beds vary from about 10 to 50 feet or more. Their distribution is restricted. Appearing at the surface on the east of Croydon they extend over a considerable tract between Addington, West Wickham, and Beckenham ; they occur at 8574. B 2 •20 GRAVEL OF HIGHER GROUNDS. o3 J- o I 6 I— I 1 •S « =L ih o a o PM 03 « to « ^ w -to so bt) a :^ Ti „^ cS <^ o c*^ =Q ;2 6 w H n3 a 00 >T3 05 tS M S 2 « . CO 3 O * 5 S • - O » " -^ '' C fl -2 ^ § 2^ 2^ O PQ 02 O O c4 00 -^ 10 o pq w BLACKHEATH BEDS — RAGSHOT SAND. 21 Bromley, Hayes Common, Keston, Chislehurst, and Eltham, and agam at Bexley Heath, East Wickham, Charlton and Blackheath. Out'ying patches lie south of Caterham and at Worms Heath near Chelsham. The soil above these deposits is dry and healthy, while the dis- tiict is picturesque and admirably adapted for residences. The situation of these gravel-beds being more elevated than that of the valley gravels, they have in this respect a decided advantage. In short they may be considered to afford sites as good generally, from a sanitary point of view, as those on the large areas of the Bagshot Beds, and of the higher gravels on the Chalk of Hert- fordshire and Buckinghamshire. Barton Sand. The higher elevations in the region of Bagshot Heath, East- hampsfcead Plain, Chobham Ridges and the Fox Hills, parts of Aldershot and Eversley Commons, comprise the Barton or " Upper Bagshot Sands," about 10() feet thick where fully developed. These beds are capped extensively by gravels which contain hard con- cretionary masses of sandstone, known as greywethers or Sarsen stones, Pirbright Common and the greater portion of the Necro- polis at Brookwood are situated on the Sands. The region is for the most part wild and picturesque, comprising much heathland and many plantations of Scotch fir. Bagshot Sand. These strata, which take their name from Bagshot Heath in Surrey, and were formerly grouped as " Lower Bagshot Beds," are most largely composed of sands, with occasional thin seams of white pipeclay and pebbly layers. The sands are usually fine- grained and buff in colour, but greenish beds are occasionally met with. The beds are sometimes indurated into an iron- sandstone with or without pebbles. To the north-east of liondon small tracts of Bagshot Sand form the hilly ground at High Beech, near Loughton, there covered irregularly by gravel. Between High Beech, Loughton, and Epping, the ground is mostly of a light and loamy nature, with here and there beds of sand and sprinklings of gravel. The fact is that the London Clay, which lies below, passes up into the Bagshot Sands by alternations of sand and clay. These mixed soils occur also over the area east of Epping, near Theydon Bois, by Gaynes and Ongar Parks, and elsewhere. More definite areas of Bagshot Sand are to be found in many parts of south-eastern Essex, at Hadleigh and Rayleigh, at Lang- don Hill, at Billericay, Stock, and near Ingatestone, at Kelvedon Hatch, Brentwood, Warley and Southweald, and again at Crab- tree Hill, near Lambourne. Here the sands are overlain in places by pebble-gravel. 22 BAGSHOT AND THANET SANDS. Again, small areas of Bagshot Sand are found at Higligate, Hamp- stead, and Harrow, Vv^here also, towards the base of the sand, pebbly layers with ironstone occur. The junction with the under- lying London Clay is at these locahties also marked by alternations of sand and clay, as shown in excavations on the Kidderpore estate, West Hampstead, on the higher parts of Haverstock Hill, and in foundations for the Drawing School at Harrow. The same features are present over parts of Richmond Park and Wimbledon Common, and by Thatched House Lodge on Kingston Hill ; while east of Copse Hill, Wimbledon, two outliers of Bagshot Sand covered with pebbly gTavel have been observed. At Hampstead the Sand is from 60 to 80 feet thick, and it has been extensively dug on the Heath, where small patches of gravel likewise occur. (See Fig. 5.) The more extensive mass of Bagshot Beds forms an important residential district, over a large area westwards from Esher and Weybridge to Ockham Common, Woodham, AVoldng and Horsell, Ottershaw, Virginia Water, Englefield Green. Sunningdale, Sun- ninghill. Ascot, Easthampstead, Wokingham, Finchampstead, aiid Aldershot. There the Bagshot Beds, almost wholly sands, range to upwards of 100 feet thick. Taken as a whole the area of the Bagshot Beds forms a picturesque, heathy country, for the most part dry and sandy, and with many fir-trees ; it is from 100 to ovsr 400 feet in elevation, and eminently adapted for building-sites Thanet Sand. These deposits consist mainly of fine sand or loamy sand, and they border the Chalk from Leatherhead, by Epsom, Ewell, Cheam, Sutton, Carshalton and Beddington, to Croydoix. Their outcrop is so narrow that it is not distinguished on the map from the Woolwich and Reading, and the Blackheath Beds. Indeed these sands exercise little influence on the land, and they do not occur to the north-west of London. From Croydon they extend by Addington, Keston and Farnborough to Orpington, Swanley and Crayford (Fig. 8) ; and the breadth of their exposure becomes more pronounced at Erith and Woolwich than elsewhere in the neighbourhood of London. The thickness of the Thanet Beds is from about 12 feet (at Leatherhead) to 60 feet. They furnish dry and healthy sites for houses. Upper Greensand. Between Guildford and Shalford, along the foot of the North Downs, and thence extending north of Shere and Gomshall to the foot of Box Hill, near Dorking, there is a narrow belt of sloping ground formed of greenish sand and calcareous sandstone. These strata, known as the Upper Greensand, are from 25 to 60 feet UPPER AND LO\VER GREENSAND. 23 tliick, and usually form a dry and sheltered tract of ground. Further on, to the north of Reigate, at Gratton and Merstham, they occupy a somewhat broader belt, and are better adapted for sites of houses. See (Fig. 9.) In this region the stone-beds have since early times been quarried for building-stone and hearth- stone. Eastward the strata again form a narrow belt that extends by Titsey and Chevening to Otford, but disappears at Kemsing. Fig. 8, Chalk-pit tvest of Cray/ord Brickyard. rW. Whitaker.) * 1. Chalk. 2. Thanet Sand 15 ft. 3. Brickearth or loam 25 ft. On the northern side of the London Basin, the Upper Green- sand appears below the Chalk escarpment, north of Wendover and Prince's Risborough. It comprises green sand, marl and cal- careous stone (malmstone), altogether about 25 feet thick. Lower Greensand. Far more important as a residential area, is that occupied by the Lower Greensand of Surrey and Kent — a tract separated irom the Upper Greensand on the north by a narrow vale of Gault clay. The Lower Greensand consists in its upper part of loose sands, the purer varieties of wliich have been used for glass- making ; and these sands, white, brown or green, are occasionally cemented into blocks of hard rock, as at Ightham. This division, known as the Folkestone Beds, is from 100 to over 200 feet tliick. Lower down in the series, but occupying a small area, are beds of clayey sand and clay, which outcrop to the south of Reigate, and extend eastwards through Nutfield and Bletchingley to Tandridge. Layers of fuller's earth are worked in these berls at Nutfield. They are known as the Sandgate Beds, and are sometimes about 50 feet thick. Below are thick beds of calcareous sandstone, occasional limestone, and sands, with ironstone and chert. These are known * " Geology of London," vol. i., fig. 6, p. 112, 24 LOWER oreeNsakd. as the Htjthe Beds, and they form the prominent escarpment. Their thickness increases from about 90 feet at Maidstone to about 250 feet at Godalming. The base of the series comprises a band of clay and loam, known as the Alherfidd Clay, sixty feet thick in places; this occupies but a narrow belt of country, and merges into the thick Weald Clay which lies below it. (See Fig. 9.) In the area under consideration the Lower Greensand may be said to vary in thickness from 250 to 450 feet. It occurs below the high scarp of the North Downs, and, extends from the neigh- bourhood of Farnham, Hind Head, Haslemere, and Godalming, eastwards past Shalford, Albury, Shere, Gomshall, Abinger, Leith Hill, Dorking, Reigate and Redhill, and onwards to Godstone, Oxted, Limpsfield, Westerham, Sundridge, and Sevenoaks. Still further it extends by Seal and Ightham to West Mailing and Maid- stone. Along this course it forms a belt, of varying width, of hilly and for the most part dry and sandy country of exceedingly pictur- esque character, there being many heaths, commons, and plantations of firs. It is admirably adapted for healthy residences, as indeed the numerous mansions and villas make manifest. Along its southern borders it rises from about 500 to 965 feet at Leith Hill, in bold scarps which constitute the range of hills overlooking the great vale of the Weald Clay to the south. (See Figs. 1 and 9.) The higher elevations are fairly bracing. Another tract of Lower Greensand, far north of London, ex- tends from near Leighton Buzzard to Brickhill, Woburn Sands, Aspley Guise, and Ampthill. Although capped here and there by Boulder-clay, and containing bands of fuller's earth and clay, it is famous for its generally dry and healthy soil and salubrious air. This pleasant region, from 300 to over 500 feet in elevation, over- looks the great clay -vale which extends from Fenny Stratford in a south-westerly direction to Aylesbury. Mixed Subsoils. Hastings Beds. Beyond the vale of Weald Clay, before alluded to, there is a varied tract of sandy, loamy, and clayey country formed by the Hastings Beds. These comprise in downward succession the Tunhridge Wdls Sands and Sandstones (220 to 350 feet), which include beds of clay at Grinstead and Cuckfield ; the Wadhurst Clay (150 feet) ; and the Ashdown Sand (upwards of 400 feet) which consists of thick beds of sand and sandstone, with alternations of clay. The main divisions are separately shown on the one -inch Geological Survey Map. Tunbridge Wells stands on this tract of Hastings Beds, which extends to the south over Ashdown Forest, to Heathfield and I— I LOWER GREENSAXD. o H t-^ o" IC ■<# 5- 5. O ■ Si QQ O t^ CO CO (N o 26 MIXED SUBSOILS — HASTINGS BEDS. Uckfield, and westward from East Grinstead to Three Bridges, and over Tilgate and St. Leonards Forests to Horsham and Cuckfield. Good sites for houses occur throughout this area, the greater part of which is an elevated sandy region, for the most part dry and diversified in scenery. The more loamy tracts are not usually unfavourable by reason of any special dampness in the nature of the subsoil. The clays, though sometimes exposed on the uplands, appear mostly in valleys, and occupy sloping ground where there is good natural drainage ; and they are usually covered by a loamy soil. Curiously enough some of the sands and sandstones belonging to the Hastings Beds are so fine in grain that in places, as Topley has remarked, " the soil holds up water almost as well as clay." Hence in examining the country " strict allowances must be made for the weather," as the percolation after heavy rain may be very slow. In a number of places the sandstones appear at the surface as natural rocks, of which well-known examples occur near Tunbridge Wells.* Woolwich and Reading Beds. These comprise alternations of sands, shelly layers (mostly clayey), pebble -beds or gravel, and mottled plastic clay. The sands are often brightly coloured red and green, and there also occur buff and white sands, locally indurated in great masses like greywethers. Seams of peat and lignite are occasionally met with, but the black staining of layers is sometimes due to manganese -ore. The subsoil is essentially a mixed one, and so irregular are the strata that actual excavation would often be needed to determine the nature of a site — whether on gravel, sand or clay. (See Figs. 7, 10, 11, 12.) The strata are from 25 to 50 feet thick, but they occupy very limited areas at the surface in the vicinity of London. Fit;. 10. — Section across the outcrop of the London Tertiary Strata. 1. Chalk. 3. Woolwich and Reading Beds. 5. London Clay. 2. Thanet Beds. 4. Blackheath Beds. They appear from beneath the London Clay along the borders of the Chalk in a belt extending from Hoddesdon, near Ware, through Hatfield Park to North and South Minims, Shenley, Radlett, Letchmoreheath, and Bushey near Watford, to Northwood and Harefield. Straggling inlying masses appear at Pinner, East- cote, Ruislip, and Ickenham. At Radlett the pebble -bed is locally * Sec W. Topley, " Geology of the Weald," Oeol. Survey, 1875, pp. 245-249. Woolwich and beading beds. 27 cemented into conglomerate, known as the Hertfordshire pudding- stone. Westwards the strata occur below gravel at Gerrard's Cross and Beaconsfield ; they appear at Wargrave and Reading, and in the picturesque outliers of Lane End, W. of High Wycombe, and Nettlebed, N.W. of Henley-on-Thames. South of London the Woolwich and Reading Beds outcrop be- tween the London Clay and Chalk in a narrow belt from Merrow and the Clandons, N.E. of Guildford, to Effingham and Leather- head. From Leatherhead onwards by Ashtead, Epsom, Ewell, and Sutton to Croydon the strata rest on the Thanet Sand, but they are concealed by gravel, between Carshalton and Croydon. Li this region they practically separate the London Clay area on the north from that of the Chalk on the south. Fig. 11, — Section south of Bushey Station, near Watford, (W. Whitaker.) * 1. Gravel 2. Mottled Clay 3. Sand 4. Sand with layers of flint-pebbles/ Reading Beds. 5. Pebble-gravel 6. Layer of Hint J 7. Chalk. East of Croydon, where the Woolwich and Reading Beds appear from beneath the Blackheath Beds, the outcrop from Addington to Farnborough is too small to exercise much influence on the ground. (See Fig. 7.) ^More marked, however, are their features along the borders of the Thames valley from Erith to Woolwich and Greenwich, They occur also over small areas at Lewisham, Peckham and Dulwich. From the limited outcrop, and from the occurrence of much sand and. gravel in this group of strata, it cannot be considered as furnishing sites liable to be injurious by reason of dampness unless in low lying situations. A particular house may happen to be placed on clay, but even on that account if it be well constructed no serious objection could be taken to the site. * •' Geology of London," vol. i., fig. 32, p. 199. 28 MIXED SUBSOILS. to P c3 -^ o M ^ zi -M — ■»?.•*; ^ > >5 o .^ fe 1,: -^ ^ c6 , O 15 stic cl clay ayers ^ > cS >»— p* ^^1:2 — ( cS T ^ a' ^ ? Mottl Dark Sand -2 ^^ .s 1 JO 't >o cS * o; .•::^ be C g ^ cS O C 5Q 5 -^ o '^d l-H rtS Ci3 cS P5 66o ?! V to X a H"5 48 LONDON WATER SUPPLY. Some of che London wells and springs in old times (1080-1810^ attained fame as holy wells and spas, such as Beulah Spa, Ber- mondsey Spa, Holywell, Bagnigge Wells, Cie'-kenwell, Sadler's Wells, London Spa, Islington Spa, and St. Cement's.* Hampstead until lately utilised its chalybeate spring ac Well Walk ; it issues from a ferruginous sandy layer in the passage-beds between the London Clay and Bagshot Beds, and was in 1897 certified as free from contamination. The first conduit for the supply of water to London was that of Tyburn, which was completed in 1239, when water was conveyed in leaden pipes to the City. Much water, too, was obtained in buckets from the river, and in 1582 the supply was facilitated by means of water-wheels attached to the arches of old London Bridge. Wooden conduits were then used, and a more extended system of supply to houses was introduced. As London increased, the supplies of water obtained from the gravels became contaminated, and the water of the Thames near London Bridge was doubtless very bad. From the close of the 17th century and subsequently, companies were formed for taking water from the Thames near Charing Cross, and higher up ; but since 1855, owing to the danger of tidal influence on the London drainage, no water has been drawn by any company from the Thames below Teddington Lock. The cutt'ng of the New River was commenced in 1608 by Sir Hugh Myddelton, and five years later the artificial channel was completed It was not till 1619 that the New River Company was formed.! Fed by springs from the Chalk near Ware, notably by that at Chadwell, in the parish of Amwell, and receiving water also from the River Lea, the New River furnished an abundant quantity of excellent water, and has for upwards of two and a-half centuries yielded the greater part of the supply needed for the growing population of northern London. This supply has latterly been augmented by deep wells sunk into the Chalk through the London Clay, etci, at Ware, Cheshunt, Hornsey, and elsewhere. Since the year 1790 the sinking of Artesian or *' flow " wells through the impervious mass of London Clay into the Lower London Tertiaries and Chalk, has been a fruitful source of water for breweries and other large establishments, t The water from * See W. Wroth, "The London Pleasure Gardens of the Eighteenth Century," 1896, pp. 3, 6. t See J. Hopkinson, Trans. Ilertfordsh. Nat. Hist. Soc., vol. vi., 1891, p. 150 ; and vol. ill., p. Ixix. J The principle of Artesian wells was ascertained at a very early period in Egypt, and the construction of such wells was revived at Artois, in the department of the Pas de Calais : hence the name Artesian. They did not Ijecome general elsewhere in France, and in other parts of Europe, until the beginning of the 19th century. Prestwich, " Water-Bearing Strata of the Country around London," 1851, pp. 8, 197. LoXDoN WATER SUPPLY. 49 the Lower Eocene sands and pebble beds (Lower London Ter- t'aries) which was at first drawn upon, proved in time to be wanting both in quantity and quaUty, although sometimes it was not to be separated from that held in the underlying Chalk. Hence it has become necessary that borings be carried deeper and deeper into the Chalk. The chief supply of water tapped by the deep borings under London may be said to have originated in the rainfall on the Chiltern Hills and North Downs, and to have percolated through the Chalk to the central portions of its mass. "When some of the earlier deep wells had been sunk, the water rose to within 40 or 50 feet of the surface, and, in a number of instances, in the lower grounds of East Essex, the Lea Valley, and at Tooting, it actually overflowed.* In 1822 water from the Chalk rose to the level of Trinity High-water mark, i.e., 12'5 feet above O.D. By the abstraction of many milUons of gallons of water a day the per- manent water-level under Central London is now about 100 feet below Ordnance Datum, and is still being lowered. It is needful to bore into the Chalk imtil some fissure is met with, whence the water can freely issue ; this may be at depths varying from 10 feet to 250 or more feet in the Chalk. Thus a boring made in 1893 at Chelsea was carried through gravel, London Clay, &c., and reached Chalk at a depth of 278 feet ; and the Chalk was bored to a depth of 250 feet. The water-level was 72 feet below O.D. A boring made in 1903 at Finsbury reached Chalk at a depth of 204 feet, and was carried to a further depth of 246 feet in Chalk. The water-level was 95 feet below O.D. It has been calculated that every 1,000,000 gallons of water drawn from the Chalk carries in solution one and a quarter tons of Chalk, Thus the water pumped out tends to open the fissures, but it lowers the plane of saturation, and diminishes the dry-weather flow of streams . t In seeking water from the Chalk a shaft, where practicable, is to be recommended, as it is not only likely to touch more fissures than a boring, but galleries or tvmnels can be driven to increase the supply. In a few instances borings have been made through the Chalk without obtaining any useful supply of water. Some of the districts to which attention has been drawn extend beyond the limits of the areas supplied by the eight London Water Companies now merged under the Metropolitan Water Board (1904) ; but many other parts are supphed by local companies. It is to be hoped that in time the entire country will be divided into " See Prestwich, " Water-Bearing Strata of the country around London," 1851, pp. 3, 45, 69. t .1. Hopkinson, Trans, ffertfordsh. Nat. Hist. Soc, vol. vi,, 1891, pp, 148, 149. S.574 D 50 LONDON WATER SUPPLY. districts to be supplied with good drinking water. At present the inhabitants of many a small country village ill suppHed with water, are not in a position to pay for the needful deep boring or reservoir. Especial attention was drawn to this subject nearly thirty years ago by the Society of Arts. A Public Corgress was summoned by the Council, and the subject was very fully discussed, and reported on in 1878. A practical scheme, however, has still to be formu- lated and carried out. The area supplied by the Metropolitan Water Board extends around London to Ware in Hertfordshire, to Romford in Essex, to Sm^dridge and Chevening in Kent, and to Esher in Surrey.* All the original MetropoUtan Companies, except the Kent Company, derived great part of their supply from the Thames (at or above Hampton) and the Lea, supplemented in some cases by water obtained from wells. The Kent Company was supplied wholly by deep wells. Moreover, it was satisfactory to learn f L'om the Report of the Royal Commission on Metropolitan Water Supply (issued in 1893) '' that the water, as supplied to the consumer in London, is of a very high standard of excellence and of purity, and that it is suitable in quality for all household purposes." The eight companies in 1902 had to supply a population of more than 6,000,000 persons and to deUver a daily average of 211,500,000 gallons, of which 48,000,000 gallons were obtained from wells and springs, and the rest from the Thames and Lea. DISTRICTS SUPPLIED BY THE METROPOLITAN WATER BOARD. Former Metropoli- tan Water L'om- poAiien. Chelsea District - East liondon Dis- trict - Grand J unction Dis- trict - Kent District Lambeth District - New River District Southwark and Vauxhall District "West Middlesex District Supply. River Thames at W. Mole- sey and Gravel Wells Lea (near Cliingford), Thames at Sunluiry, Gravel and Chalk Wells Thames near Hampton and Gravel Wells Chalk Wells and one in Lower Greensand - Thames at A\ . Molesey and Ditton, and Gravel Wells Lea (below Hertford), Thames and Colne, Springs and Chalk Wells Thames at Hampton,Gravel and Chalk Wells - Thames at Hampton - Localities in the District Supplied. See Bloomsbury, Chelsea, Fulhain, ]\Iarylebone, Westminster. Buckhurst Hill, Cheshunt, CliigweH, Cliingford, Islini'ton, Tottenham, Step- ney, Stratford. Acton, Chiswick, Ealing, Marylebone, Paddington. Bromlej^ Chislehurst, Dart- ford, Greenwich. Camberwell, Kingston-on- Thames, Streatham, Thames Ditton, Wimbledon. Clerk en well. Hackney, Hampstead, Islington. Barnes, Dulwich, Kew, Put- ney, Wandswoitli. Hampstead, Hcndon, Ealing, Hounslow, Mortlake, Rich- mond. Bolton. Ed. 2, by 36 " London Water Stipi)ly," by Col Sir Francis ; P. A. Scratcliley, 1888 ; " Loncion Water Supply," by H. C, llicliards and W. H. C. Payne. Ed. 2, by J. P. H. Soper, 1899 ; and Ann. Summary of Registrar-( General for 1903, Table 18. LONDON WATER SUPPLY. 51 The Thames and its tributaries above the intakes of the Water Board contain, of course, much impurity, and in seasons of heavy rain and flood, when much foul matter is carried into the water by surface-washings, the amount of impurity is much greater than in dry weather when the river is maintained by springs. The system of filtration introduced in 1829, and since then vastly improved in various ways, especially since 1884, has, however, been very efficient in providing good water. It is now known that the slime formed on the surfaces of filter-beds contains bacilli which are the most effective agents in the bacterial purification of the water. The sand itself simply removes suspended matter, and forms a support for the active slimy layer. It is signifi.cant that the typhoid bacillus was never found in the water supplied by the companies who drew from the Thames, though, of course, considering the immense quantity of water used and the tiny amounts that can be periodically examined, the fact must be taken cum grano* Nevertheless, the character of the Thames water above Teddington has steadily improved, owing to the care taken by the Thames Conservators in keeping the main river and its tributaries as free as possible from pollution. Although the water suppUed over the London area is moder- ately hard, yet it is well known that many of the healthiest dis- tricts are those with hard water. Lead-poisoring may for a time be produced by soft water when conveyed in new leaden pipes. The power of dissolving lead in dangerous quantity is attributed to the peaty acids that are met with especially in moorland waters. Curiously enough, bacteria are said to increase more rapidly in water that is comparatively pure than in that containing mineral ingredients, f Nevertheless, hard and sol't water appear to be equally good for drinking-purposes, when they attain a proper standard of purity. Deep well water, if allowed to stand, is said soon to become full of bacteria. If stored, such water, and also spring water, should be kept in covered reservoirs, since the access of light favours the growth in these waters of aquatic vegetation, which by its decay may taint the water. Sir E. Frankland and Dr. R. Koch adopted as a standard of bacterial purity 100 (non-pathogenic) microbes per cubic centimetre. Chalk areas are now and again looked upon with disfavour by individuals who have a tendency to gout, because it is thought * E. Frankland, Discourse at Roy. Inst., Nature, April 30, 1896, p. 621 ; L. C. Parkes. Trans. Sanit. Inst, vol. xv., 1895, p. 245. See also researches of Prof. H. Marshall Ward, on the Bacterial Flora of the Thames, Proc. Roy. Soc, vol. Ixi., 1897, p. 415. + Trans. Sanit. Inst, vol. xi, 1891, p. 234 ; Prof. H. Robinson Idem. vol. XV, 1894, p. 577 ; 30th Ann. Rep. Local Government Board, 1900-01, Supplement "On Lead Poisoning and Water Supplies," by Dr. A. C. Houston . 8574 D 2 52 IIUIIAL WATER SUPPLY A?sD SA>:iTAtrON\ that the chalky water woU:d aggravate the complant. This, however, is a fallacy, the chalky deposits in gouty persons being of a chemical nature quite difEerent from carbonate of lime. Moreover, it is not easy in the area adjacent to London to obtain other than hard water, much of it being derived directly from wells in the Chalk. The hardnes3 of Chalk waters is mostly of the kind known as " temporary," being due to carbonate of lime which is held in solution by carbonic acid. This it is which furs our tea-kettles and boilers, and wastes our soap. Each degree of hardness is equal to one grain of carbonate of Ume per gallon of water. The hardness may be removed by the addition of quicklime in definite quantities to the water ; a process introduced by the late Dr. Thomas Clark of Aberdeen. If the initial hardness be icom 15° to 20°, it can be softened to 4° or 5° by Clark's process. No potable water should contain more than 25 grains of mineral matter per gallon. A soft water has less than 6° of hardness.* Highly ferruginous water may be detri- mental to health ; and it has been observed that goitre is prevalent where limestone-rocks are impregnated with metallic sulphides.! Rural Water Supply and Sanitation. The following statistics relating to the water supply of dis- tricts outside the limits of the Metropolitan AVater Board may be useful; : — Urban and Rural WaterCoynjmnies Slough South-west Suburban. Rickmansworth and Ux- bridge Valley. Colne Valley. Herts & Essex, South Esse^. Suppli/. Districts supjdied. Chalk wells. Colnbrook, Datchet, Farnham Royal^ Langley, Slouch, Stoke Poges. Chalk wells Ascot, Eghani, Feltham, Hanworth, and Thames Laleham, S'uthall, 8taiaes, Stfinmore, I Sumuagdale, Sunninghil!. I Abbots Langley, Bovin;^don, Greenford, Clialk we'i's Harefield, Harlington, Hayes, Hilling- don, Iver, King's Langley, Northolt, Perivale, Rickmansworth, Sarratt, West Drayion, Yiewsley, etc. Chalk wells. Bushey, Edgware, Elstree, Watford. (softened). Chalk wells. Abridge, Epping, Theydon Bois, etc. Chalk wells. Barking, Brentwood, Dagenham, Graj's , Havering-atte-Bower, Hornchurch, Ilford, N. and S. Ockendon, Purflcet, Rainham, Romford, Shenheld, Upmin- ster, etc. * For Notes on Water Softening see S, Eideal, " Water and its Purifica- tion," 1897, p. 191 ; also " The British Clayworker " for March, 1905, p. 390. t Topley, Trails. Sanit. Inst. vol. xi., 1891, p. 224. X For the above information we are indebted to "The Water Works Directory and Statistics," 1903 (Hazell, Watson & Viney). See also p 8. RURAL WATER SUPPLY AXD SANITATION, 53 Urban and Rural WaterCompanies East Surrey. Supj)ll/. Chalk Avells. (softened). Sutton District. Chalk wells. West Surrey. Woking. Wokingham District. Districts supidied. Thames. Chalk wells and Thames. I Clialk well. Betohworth, Caterham, Chipstead, Couls- don, Godstone, Horley, Kenley, Lin:- field, Merstham, Nutfield, Purley, Red- hill, Reigate, Sanderstead, Walton, Warlingham. Banstead,Beddington, Carshalton.Cheam, Cuddington, Ewell, Morden, Sutton, Wallington, Woodmanstern. Addlestone, Byfleot, Chertsey, Hersham, Shepperton, Oatlands, Walton-on- Tbames, Wey bridge. Bisley, E. and W. Clandon, Horsell, E. and W. Horsley, Merrow, Ockham, Pirbright, Pyrford, Ripley, Send, Wisley, Woking, Worplesdon. Wargra\e, Wokingham, etc. Other localities supplied from Chalk wells are Aldershot, Amershajn, Aylesbury, Baruet, Beaconsfield (from Amersham), Berkhampstead, Chelmsford, Cheshani, " Croydon, Dunstable. Ejjsom, Goring, Great Marlow, Guildford, Harrow, Harpenden, Hemel Hempstead, Henley- on-Thames, Hertford, High Wycombe, Hitchin, Leigh-on-Sea, Maidenhead, Eichmond, Iloyston, )Satfron Walden, St. Albans, Stevenage, Streatley, Ware and Windsor. Localities supplied with soft or fairhj soft tmter from springs or wells in Sand and Sandstone include, from the Ilastinr/s beds : — Balcombe, Cuckfield and Tunbridge Wells ; and from the Lower Greensand : — Petersfield, Godalming, Haslemere, Dorking and Sevenoaks. Reading is .sujiplied from the river Kennet, It should be borne in mind that the Lower Greensand and Hastings beds are variable in mineral characters, and consequently the water held by them varies locally. In parts of Kent the Lower Greensand water is hard, when derived from the sub-division known as the Hythe beds, which locally contain calcareous layers. Water from the Hastings beds sometimes contains sulphate of lime, and is sometimes alkaline from the presence of carbonate of soda. In selecting a site outside the range of any Water Company's district, and where there is no local supply from a deep-seated or other source, the nature of the water-bearing strata must, in the first place, be carefully considered. Most villages, like those of old in the London area, have been built on porous subsoils from which the water-supply was readily obtained, and in most cases such shallow sources have become more or less contaminated. No serious outbreak of illness may hitherto have occurred, but there is always a risk of its appearance. The soakage from stables and farmyards, from cess-pits and possibly from burial-grounds, may lead to disastrous contamination in such situations, and, indeed, the attention of the Local Government Board is constantly being drawn to outbreaks of typhoid fever that arise from the 54 PvURAL WATER SUPPLY AND SANITATION. contamination of wells. That illnesses are not more frequent is due no doubt to the otherwise healthy surroundings of those who live a country life. A bed of clay intervening between the suriace-deposits and deeper-seated water-bearing strata will prevent contamination at this lower level, if the well be properly bricked and cemented to a httle below the base of the porous surface-deposits. In the absence of geological conditions favourable for a supply of water by a deep well or boring, a supply must be sought from a distance. On some of the great clay- vales where local sources of water, obtained from small tracts of gravel, have been condemned, there is great difficulty as well as expense in procuring supphes. The provision of sewers and of a piped water-service should generally go together. In the absence of a sufficient supply of water for flushing, sewers are liable to become blocked and offensive ;' and on the other hand, in the absence of sewers a supply of watsr, laid on in pipes to each house, increases the volume of waste liquid and renders its disposal more difficult ; cess-pools soon fill, and unless frequently emptied they overflow and cause sewage nuisances, The great trouble in rural districts is with the sewage. In regions where there is no main drainage and no system of water- supply, it is by no means unusual to sink " bhnd " or " dumb wells " into porous strata to carry off the sewage. In places where seweis are not available many difficulties would be over- come by the adoption of the pail or earth-system instead of water-closets and cess-pools. Dr. G. V. Poore has strongly advocated the plan, and experiments which he has made show that two or three feet of soil filter out bacteria, the subsoil of a greater depth being generally free from these micro-organisms. He has urged that if the soHd refuse matter from houses be buried in the " Hving earth " (that is in the top layer of culti- vated ground or natural soil), no evil should result. Putrescible matter when buried in earth undergoes decomposition without putief action ; the danger arises from a mixture of excrement and water in sewer or cess-pool, the excrement being the ingredient against which dangerous infective properties have been proved again and again. He remarks that " The Hving mould is our only efficient scavenger, which thrives and grows fat upon every kind of organic refuse ; our only efficient filter, a filter which swells and offers an impassable barrier to infective particles, a filter which affords a sure protection to our surface wells. When we perforate the living humus with a pipe, and take our dirty water to the subsoil, we, as it were, prick a hole in our filter, and every chemist knows what that means."* Hence, shallow wells should * Trans. Sanit. Inst., vol. xi., 1891, pp. 33, 36, 41, 47, etc. ; the Lanc^, Deo. 14, 1895, p. 1483 ; " Essays on Rural Hygiene," p. 192. Ef ' RURAL WATER SUPPLY AXD SANITATION; 55 always be cemented some 6 or 8 feet down, and there should be no cess-pits or other subterranean receptacles for refuse in their vicinity. Attention has been frequently directed to the evils that, sooner or later, may arise from such systems of " dead wells " and under- ground soakage, whether carried into the Chalk, the Thanet Sands, the Reading Beds, or the Bagshot Sands. It should be remembered that all porous strata are water-bearing, that the supply of water, especially in the case of the Chalk, may be drawn upon for drinking-purposes, and that contamination introduced into such strata may be conveyed underground to some distance from the sources of pollution. It is also well to bear in mind the important legal decision of 1885, to which Mr. Whitaker has drawn particular attention, that while every owner has the right to draw unde ground water to an unlimited extent, no owner has the right to pollute a source of water-supp'y common to his own and other wells, f In his Address to Section III. of the Sanitary Institute (1897), Mr. Whitaker urged that where a public supply of water is ob- tained from porous strata, such as the Chalk, occupying large areas at the surface, then a certain tract of ground around the water- w^orks should be preserved from surface-contamination, whether by sewage-farm, cemetery, or. other source. Shortly after those remarks were written (in thE - ALDBOROUGH, &c. By W. H. Dalton. Edited, with additions, by W. Whitaker. Is. - SOUTHWOLD. By W. Whitaker. 2s. 6d. • STOWMARK};t. By W. Whitaker, F. J. Bennett, and J. H. Blake. Is. - DISS, EYE. &c. By F. J. Bennett. 2s. - HALESWORTH and HARLESTON. By W. Whitaker and W. H. Daltox. is. 61 SE • 51 NE - 53 SE - 63 N£ - 65 . 66 SW • 67 NW - 67 . 68 B - 68 NW, SW - 69 . 70 . 71 NE - 79 NW - 79 SB - 80 NW - 80 SW - 81 NW, SW - 82 SE - 82 NE - 83 . 84 . 86 . 87 NW - . 87 SW - 88 SW . 88 SE - 88 NE - 89 SE - 90 SE - 90 NE - 91 SW - 91 NW - 92 SE - 93 NW - 93 NE - 93 NW - 93 SE, 94 SW 94 NW - 94 NE - 95 SW, SB - 95 NW - 96 SE - 96 NE - 96 NW, SW - 97 SW - 97 NW - 98 NE - 102 SW - 104 SW, SE • 107 . 108 SE - 108 NE - 108 SW - no SW - 110 NW - 110 NE - 110 SE - 123 141 . 155 . 156 231 232 248 249 262 26a 268 282 298 314 315 317 325 328 :i29 332 334 350 355 & 3 >^ SHEET MEMOIRS OF OLD SERIES MAPS-r « T>^ A 000 553 610 I