LD4C: Loess Deposits on Four Continents

 LD4C: a new enterprise- Loess Deposits on Four Continents. A publication by 'Geosciences' edited by Ian Smalley & Slobodan Markovic; your recent and radical thinking on all aspects of Loess. Go to Webpage https://www.mdpi.com.journal/geosciences/special issues/loess deposits on four continents. Contributions invited.

emails: ijsmalley@gmail.com; slobodan.markovic@dgt.uns.ac.rs

Twenty Books on Loess: A subjective progression 1700-2000

Books are important in the Loess story: the 20 books are important- are they the most important?- that depends on your interests and your viewpoint. They are listed in roughly chronological order; it is a very subjective list, and selection and discussion relate to personal use and experience.

Every generation enjoys the use of the vast hoard bequeathed to it by antiquity, and transmits that hoard, augmented by fresh acquisitions, to the future ages.                                                                      Lord Macaulay: Essay on Milton

1.  Marsigli 1726

Luigi Ferdinando Marsigli; Danubius Pannonico Mysicus (in Latin) 6 volumes

Marsigli, serving the Austro-Hungarian Empire, was stationed at several convenient places in Central Europe. Convenient that is to make the first European record of loess. His diagrams of the Danube bank were the first representations of loess in situ in a stratigraphic situation. It seems likely that there were earlier representations of loess landscapes in China but we can assign Marsigli priority in Europe. They were published in his great book on the Danube, in 1726. [see LG blog 22 & 25 May 2020]

2.  Leonhard 1824

Karl Caesar von Leonhard; Charakteristik der Felsarten; Joseph Englemann Verlag, Heidelberg. Three volumes published in 1823 & 1824. Descriptions of ground materials; volume 3 contains section 89 Loess; this is the defining and descriptive arrival of the loess concept.

Hambach, U., Smalley, I. 2019. Two critical books in the history of loess investigation 'Charakteristik der Felsarten' by Karl Caesar von Leonhard and 'Principles of Geology' by Charles Lyell. Open Geosciences 11, 447-451. doi:https://10.1515/geo-2019-0032   

3.  Lyell 1833

Charles Lyell; The Principles of Geology; John Murray London 3 volumes 1830-1833. The critical loess material appeared in vol.3. The great success of the Principles meant that loess awareness quickly became worldwide. Lyell revised and republished the Principles throughout his life; the 12th edition was being prepared when he died. The tone became more philosophical as the series progressed and the loess references have disappeared by the time of publication of the 6th edition. Vol.3 (the Loess volume) reached Charles Darwin in Valparaiso in 1834.

4.  Richthofen 1877

F.von Richthofen; China: Ergebnisse eigner Reisen und darauf gegrundeter Studien, 5 vols. Dietrich Reimer Berlin. Loess discussions and descriptions in vol.1.

5.  Free & Stuntz 1911

E.E.Free, S.C.Stuntz; The movement of soil material by the wind, with a bibliography of eolian geology. U.S.Department of Agriculture, Bureau of Soils Bulletin 68, 263p.

6.  Soergel 1919

W.Soergel; Losse, Eiszeiten und palaolithische Kulturen; Carl Fischer Jena 177p

7.  Scheidig 1934

Alfred Scheidig; Der Loss und seine geotechnischen Eigenschaften; Verlag Theodor Steinkopf  Dresden u.Leipzig 233p. [Geologie und Verbreitung, Erdstoffphysik, Erdbaumechanik und Geotechnik der Losse und Losslehme, Schluffe, Silte und anderer Stauberden, Aschen und Staube].

It was 1970; I was in the library of the Sedgwick Museum in Cambridge. I was visiting David Krinsley who was spending a year as visiting fellow at Churchill College. I think I had arranged to meet him at the Sedgwick Museum, I was waiting for him and idly browsing when I came across a catalogue for Otto Koeltz bookseller- and it listed a copy of Scheidig for sale. Up to that moment it had never occurred to me that I could actually own a copy of this mythical book.

8.  Denisov 1953

N.Ya.Denisov; Engineering Properties of Loess and Loess-like Clay Soils. (in Russian) Gosudarstvennoe Izdatel'stvo Moscow 154p. The copy in the Loess Letter Archive is the 2nd edition so its this edition that gets reported; 6000 copies printed. A key work in the study of the hydroconsolidation and structural collapse of loess ground; fig.32 is the iconic picture of the collapse of a canal in Central Asia; when the collapse problem became really apparent- when it began to obsess the geotechnical community in the Soviet Union.

9.  Charlesworth 1957

J.K.Charlesworth; The Quaternary Era (with special reference to its glaciation); Arnold, London, 2 volumes, 1700 pages. The great and amazing Quaternary compilation; two substantial volumes. Volume one contains a substantial section on loess. It seems incredible that someone would attempt a survey of all aspects of the Quaternary- involving a very committed bibliographical effort, although Charlesworth did admit that publications in many languages had escaped him. Unfortunately he used a very complicated reference system (unique to him) which was difficult to use. Volume 2 was so thick that it was difficult to manipulate, but it contained a key section of the bibliographic apparatus.

Chapter 26 (vol.1, pp 511-558) deals with loess and has 709 references listed.

Charlesworth 1957 was an amazing scholarly achievement- a comprehensive study of all the literature on the Quaternary; such a task for one scholar, and such an incredible result. The loess section is still relevant and repays study- there are discoveries to be made in the Charlesworth hoard. He quotes Goethe to this effect "Wer kann was Dummes, wer was Kluges denken; Das nicht die Vorwelt schon gedacht?"

10. Woldstedt 1954

Paul Woldstedt; Das Eiszeitalter: Grundlinien einer Geologie des Quartars. Ferdinand Enke Verlag Stuttgart Bd,1. This is a work in three volumes; vol.1 contains the general discussion on loess; more accessible than the Charlesworth account but lacking the amazing detail.

11. Kriger 1965

N.I.Kriger; Loess, its Characteristics and Relation to the Geographical Environment; Izd-vo Nauka Moscow 296p (in Russian). The critical book in the study of Russian loess. For such an important book it is surprisingly little known and appreciated, OCLC reports that it is held by eight libraries worldwide; add to that one copy in the Loess Letter archive- which was supplied by Alexander Alexiev of the Bulgarian Academy of Sciences. The impressive bibliography was published separately by Loess Letter (Loess Letter Supplement 13). Only 1350 copies were printed; see Smalley 1980 p.46 for discussion-entry 16 on this list. The Loess Letter map series published the Kriger 1965 map of loess distribution as its no.1 production, and reproduced the section on the history of loess studies as a Loess Letter Supplement (no.10 June 1986- for the INQUA 1987 Ottawa Congress).

12. Schultz & Frye 1968

C.Bertrand Schultz, John C.Frye; Loess and related eolian deposits of the World; University of Nebraska Press Lincoln 369p. [Proceedings of the 7th INQUA Congress, vol.12].

13. AFEQ 1969

AFEQ; La Stratigraphie des Loess d'Europe (Supplement au Bulletin de l'Association Francaise pour l'Etude du Quaternaire) CNRS-AFEQ Paris 176p.

AFEQ 1969. A bibliographic problem- which only concerns a tiny handful of loessic bibliographers. How shall AFEQ 1969 be described and classified? How can it sensibly be referred to? It needs to stay in view, it represents a critical moment in the history of the INQUA Loess Commission. It was produced for the Paris INQUA meeting of 1969 (8th) and distributed to delegates. The LL Archive contains two copies- those of Aart Brouwer of Leiden University and Claudio Vita-Finzi of University College London. How many were printed? 500? 1000? enough for each delegate to have a copy in their package of conference materials?

OCLC shows quite a good distribution in the world's libraries. It lacks a stipulated editor, and was not commercially published; well before the days of ISBN numbers- not mentioned in Pye (1987), published by CNRS, printed in Marseille.

AFEQ 1969 is Julius Fink's setting out of the plan of action for the INQUA Loess Commission. Before 1969 the Loess Commission was a Sub-Commission, it became a full Commission at the Paris Congress. The Loess Commission was Fink's vehicle- a setting for his vision of the development of loess stratigraphy in Europe- of the contribution of loess investigation to the development of Quaternary science in general.

14. Berg 1964

L.S.Berg; Loess as a product of Weathering and Soil Formation. Israel Program for Scientific Translations, Jerusalem 207p. Translated from Berg's autobiography 'Climate and Life'

Here is the Berg vision of the processes of loess formation- this is essentially the same view that Berg advanced in 1916; this is the 'in-situ' or 'pedological' theory of loess formation. It is a remarkable book; Berg was a remarkable scholar and he published his loess theory throughout his scholarly life, mostly in Russian. The best version, ironically enough, is probably this IPST version.

15. Smalley Benchmark 1975

Ian J.Smalley; Loess Lithology and Genesis [Benchmark Geology 26] Dowden Hutchinson & Ross Stroudsburg

It was Rhodes Fairbridge's idea- a series of books which would contain the basic, fundamental ideas in the geo-sciences- the 'Benchmark' series in geology. He proposed one on loess in the early 1970s, and, after some consultation it was produced as volume 26. Julius Fink, as President of the INQUA Loess Commission, participated in the discussion and proposed that the volume focus on matters sedimentological rather than stratigraphical. He felt that, at the time, there was too much muddle and confusion in the world of loess stratigraphy that the volume should focus on problems related to origin, nature and distribution; so the focus was 'Lithology & Genesis'

16. Smalley Partial Bibliography 1980

Ian J.Smalley; Loess A Partial Bibliography; GeoBooks(Elsevier) 103p. It is a partial bibliography in two senses; it is partial in the sense that it is not complete- no bibliography can ever be complete, and loess with the wide range of topics, locations and languages has no chance of being complete; and it is partial in that it reflects the interests and opinions of the compiler, who tries to be neutral and even-handed but is victim to his background and education and linguistic proclivities.

GeoBooks in Norwich produced a series of very well made but under-appreciated bibliography volumes, Loess was no.7 in the series. GeoBooks/GeoAbstracts did an excellent job, in pre-internet times, of keeping the geoscience community informed. The GeoAbstracts series was much admired and appreciated and, of course, vanished instantly when Eworld arrived.

17. Liu Tungsheng 1988

Liu Tungsheng (editor); Loess in China (Springer series in Physical Environment 5); China Ocean Press Beijing, Springer-Verlag Berlin 224p. ISBN 3-540-16717. The journal Progress in Physical Geography chose this book as a classic publication.

18. Pye 1987

Kenneth Pye; Aeolian Dust and Dust Deposits. Academic Press London, 334p. ISBN 0-12-568690-0. This is a very good snapshot of loess ground knowledge in the early 1980s.

19. Rozycki 1991

S.Z.Rozycki; Loess and Loess-like Deposits; Ossolineum Polish Academy of Sciences, 187p. ISBN 83-04-03745-9. The Polish language edition was published in 1986 by Studia Geologica Polonica. Copies donated to the Archive by Eric Robinson of University College London and Zdzislav Jary of the University of Wroclaw.

20. Trofimov 2001

V.T.Trofimov (editor); Loess Mantle of the Earth- and its Properties (in Russian); Moscow University Press 464p. ISBN 5-211-04336-7. The copy in the Archive was donated by Andrei Dodonov, who was a contributor. This book is essentially an updating and upgrading of Scheidig 1934; a large section on loess in general, followed by a section devoted to geotechnical aspects and engineering problems. Only 500 copies were printed. Reviewed in Engineering Geology vol.255, p.252.

London Stock Bricks in the Bazalgette sewers: inadvertent excellence? [speculative connections/ manifest virtues]

Over 300 million bricks were used in the construction of the Bazalgette sewer system for London. During the construction period there was a huge demand for bricks (and bricklayers) and the prices rose considerably. The obvious source of bricks was the multitude of brickworks around London all producing the London Stock brick- the classic brick made from the local brickearth.                                                                                                                                                                                                           

                                                                                                                                              

These bricks had certain properties and virtues- it appears that they were well suited for sewer construction. How many of Bazalgette's 300+ million bricks were London Stock bricks? It would seem logical that most of the Bazalgette bricks were London Stocks.

Was Bazalgette aware of all the excellent properties that LSB possessed and that made them specially suited for a complex drainage system, or did he take an 'overall' view of construction bricks and not distinguish with particular care among the various types- for such a careful engineer this latter approach seems unlikely?

It is possible to list a set of remarkable advantages that the LSB possessed; an excellent range of properties which has contributed to the success and longevity of the sewer system. The range of virtues is impressive: moulding and making virtues, strength virtues, dimensional virtues, chemical virtues, geographical virtues, etc..

Moulding and Making

The handmade brick is made in a mould. Each single brick is formed from brick material which is pressed into the mould by the moulder. He (invariably he) presses the material into the mould using the adequate and learned amount of force. This to some extent compacts the material and establishes the initial particle structure- a modest tensile strength develops as compression enhances particle contacts- the brick can now be handled and moved to a drying region. 

The BE(as ground material) has a packing density P of perhaps 0.5, which is a voids ratio e of 1.0. Half of the space is taken up by solid mineral material, half of the space is space. If BE is compacted (remoulded and then compacted)the P value rises to perhaps 0.6-0.7- and this P value stays relatively high even after firing. The actual density of a typical LSB is around 1845 kg/m3. The density of Q is about 2650 kg/m3- with a few assumptions (always a few assumptions) this gives a P value of around 0.7- still quite a lot of porosity in a fired brick. This allows combustion gases (from the dispersed spanish) to escape and gives the brick good drainage characteristics.

Strength

Structure: the essence of a loess/brickearth deposit is structure- the way that the constituent particles are arranged in the ground system. It is the open airfall structure of the deposit which causes the geotechnical problems with loess ground- when loaded and wetted the loess ground structure collapse; hydroconsolidation ensues, subsidence occurs. The metastable nature of the ground causes problems. It also allows easy digging. The man with the spade fares better in loess ground than in ordinary clay-rich ground which can be 'heavy' or 'sticky' and difficult to manipulate. The nature of loess ground means that thick loess deposits can be dug and successfully utilized. Easily dug and easily manipulated- ideal ground for the hand making of bricks; an open internal structure and not too much clay mineral content.

The particulate nature of loess/brickearth underpins all considerations of the development of properties in LS bricks. The ground nature is relatively complex but some chancy generalisations can be attempted. BE is a silty material; assume a mode size of around 30 um- and most of these particles will be quartz. The mode shape of the mode size Q particle can be calculated (with a few necessary assumptions: eg Q is isotropic). There is a probability approach to this problem, or it can be tackled via a very simple Monte Carlo method. If the particle shape is defined by the orthogonal box into which it just fits: the mode shape can be calculated to be about 8-5-2, these are the side ratios. It is a remarkably flat particle- it will eventually determine and dominate the internal structure of the LS brick- and provide its great strength when the particle contacts are emphasized and reinforced. The moulder produces a tight random packing of flattish particles in a cohesive plastic solid.

Dimensions

For a drainage tunnel it is useful to have the surface as smooth as possible- flow should not be impeded in any way. The accurately dimensional LSB allows careful smooth tunnel construction. The nature of BE allows for efficient filling of the brick mould and this ensures good dimensionality and sharp edges-good arris structure.

Chemistry and Mineralogy

The high Q content in the LSB gives it strength and abrasion resistance, and resistance to chemical erosion. The low clay mineral content (of not particularly clayey clays) allows relatively easy melting in the firing sequence. The eutectic in the SiO2-Al2O3 system is close to the silica end of the system; the components in the eutectic system are silica and mullite.

Location and Transportation

The geography is remarkable. The brickearth is on hand or very close to hand. The close to hand brickearth is connected by an efficient transport system directly to the site of the construction activity, and also serves to deliver supplementary fuel to the brick makers. The most significant brick construction in the world is to be emplaced at the heart of the brick universe; hard to imagine a more suitable location- a more apt location.

The problem (of building an extensive sewer system) arose at the centre of a great brick using universe; every fully laden Thames barge coming up from Sittingbourne delivered 50,000 bricks- to be able to use these to build the sewer system and to save the lives of Londoners was an amazing stroke of fortune. The LSB would appear to have been almost ideal for building a large and complex sewer system- so many aspects of its nature pointed to it being well suited to the job in hand.

Choice or chance?  The virtues of London Stock bricks for the construction of the Bazalgette sewer network in Lonfon (c.1860-1880).  Ian Smalley, Arya Assadi-Langroudi, Grenville Lill . British Brick Society Information 148, 10-19, September 2021.

Star Lane & Cherry Orchard Lane: Two brickworks in Essex

 Star Lane brickworks in Essex [TQ 935870]; Cherry Orchard Lane brickworks in Essex [TQ 857898]; south of the River Crouch, near Great Wakering, near Rochford; Brickearth deposits used to make London Stock bricks; among the longer lasting of the Thames Valley brickworks; owned at one time by D.&C. Rutter- who owned brickworks in Crayford. Both sites investigated by Grenville Lill in the 1970s; his TG studies on the London brickearths succeeded and amplified those of Freeman (1964). 

Lill, G.O. 1978.  The nature and distribution of loess in Britain. PhD thesis University of Leeds; etheses. whiterose.ac.uk

London Stock bricks

Alan Cox 1997.  A vital component: Stock bricks in Georgian London.  Construction History 13, 57-66.

The London Stock is a type of brick the manufacture of which is confined to London and south-eastern England (particularly Kent and Essex). It is made from superficial deposits of brickearth (Loess) overlying the London Clay, which are easily worked and produce a durable, generally well-burnt brick. This durability actually increases, since the London Stock brick has the fortuitous advantage of hardening with age and in reaction to the polluted London atmosphere..

Other characteristics of the London Stock result from its method of manufacture, two stages being especially important. The first of these is the practice of mixing the clay with what has been variously known as Spanish, soil, town ash, or rough stuff- that is London's domestic rubbish, which contained a large amount of ash and cinders. The addition of this sifted ash provided a built-in fuel when the bricks were fired..

I.L.Freeman 1964.  Mineralogy of ten British brick clays.  Clay Minerals Bulletin 5, 474-486. 

Sample 63AH; London Stock brick mixture; mainly Pleistocene from Kent.  75% brickearth, 10% estuarine mud, 10% washed chalk, 5% sifted town refuse. The chalk is added to produce the desired yellow colour. Freeman carried out thermogravimetric analysis on his brick clay samples using a Stanton Redcroft TR01 thermobalance.

The TG curve for 63AH suggests not much moisture loess at relatively low temperatures, this would be expected for a material with a relatively low clay mineral content. This is also reflected in the low weight loss at dehydroxylation temperatures. Greater weight loess occurs at higher temperatures where there may be decarbonation reactions from the chalk in the system. 62AK has larger weight losses at moisture loss temperatures and dehydroxylation temperatures indicating a larger clay mineral presence.

This is a very rough first-plotting of the DTG curve for the Freeman sample 63AH- the brickearth mixture. It shows two main thermal events (c.f. the DTA results above); four events can be tentatively identified: A the loss of adsorbed water- not very much water, not strongly held; B combustion of organic material, again not a great reaction, not a lot of organic material present; C clay mineral dehydroxylation, the classic clay mineral reaction, showing a modest amount of clay mineral material in the sample; D carbonate loss CaCO3 >  CaO +  CO2, the added chalk has an effect here, not a huge reaction, only a small % of chalk added. The whole 63AH DTG curve looks quite like the DTG curve for a Canadian quickclay; the dominant quartz of course offers no analytical signal.

For more on DTG applications see: Fordham, C.J., Smalley, I.J.  1983/4 High resolution derivative thermogravimetry of sensitive clays.  Clay Science 6, 73-79. 

Making bricks from Loess

 Large parts of London are made from loess. London grew in the 19th Century; thousands of houses were built with loess bricks- bricks made from the London Basin brickearth. London was well placed with respect to bricks; it could become the great brick-built city. The thousands of houses were all heated by open coal fires which produced vast amounts of ash and cinders- which was collected by 'dust-men' and concentrated into vast dust heaps. This could be sent by sailing barges to the downstream brickworks to be used in the making of the classic Thames 'stock' bricks.

Artist: Edward Henry Dixon 1822-1884.  The cows are grazing near Randall's Tile Yard, York Way (near Kings Cross) London. The triangular structures on the left are tile kilns, a typical tile kiln could be 70 feet high. They can be seen again in the drawing of the Somers Town dust heap (below), and in the York Way panorama.

The brickearth was universal in the Thames valley and there were brick and tile works all over London. Certain brick related locations have become well known via references in diaries and novels and other writings, and by representations by a range of artists. The most famous region is probably that at Battle Bridge, near the current Kings Cross Station, close to the old Smallpox Hospital (which appears in several E.H.Dixon pictures); close to Somers Town, at the southern end of York Way.

Signed EHD 1835. That is York Way; just off the bottom of the picture is the Regents Park Canal.

Charles Dickens last full length novel, Our Mutual Friend 1865, features a dust heap- the novel is based on the article 'Dust; or ugliness redeemed' by R.H.Horne 1850, which appeared in the journal Household Words (published by Dickens). The site of the Smallpox Hospital is now occupied by St.Pancras Station, adjacent to the British Library and Kings Cross Station and the Francis Crick Institute.  Nicodemus Boffin, the most agreeable character in Our Mutual Friend, lived near the great dust heap at Battle Bridge.

The building with the small dome is the Smallpox Hospital. This is the Great Dust Heap at Somers Town; this is the dust heap that was sold to Russia in 1848 for £40 000 to assist in the rebuilding of Moscow. Top right can be seen tileyard structures; local brick materials being produced.

This is Mr Boffin, his fortune is based on dust, his passion is for books. "Where I live, said Mr Boffin, is called The Bower.. up Maiden Lane, Battle Bridge, ask for Harmony Jail, and you'll be put right.."

Wegg looked into an enclosed space where certain tall dark mounds rose against the sky..."

E.H.Dixon 1837 appears to have produced two versions of this picture- of the great dust heap. This is the 'dark' version. Note the cloud of dust being raised by carpet beating. The other version, the 'light' version is reproduced in the previous blog. These dust heaps provided subsistence for a whole variety of people, who sorted the mixed materials into various useful sub-classes. R.H.Horne 1850 wrote of..

"..  the next sort of cinders, called the breeze because it is left after the wind has blown the finer cinders through an upright sieve, is sold to the brickmakers. "

For an excellent discussion of dust heaps and the story of the dust heap being sold to Russia see:

Cox,A., Hounsell, P., Kempsey,S., Kennett,D.H., Worthy, S. 2017.  London's dust mountains and bricks to rebuild Moscow after 1812.  British Brick Society Information 137, 9-34.

Questions about Brickearth

Two sets of questions: 1 historical & 2 scientific. Quite a lot of explanation required. The brickearth being considered is the brickearth found in south east England, particularly in south Essex and north Kent. This is what we now think of as brickearth. The Oxford English Dictionary OED (which will be our main etymological source) has a geological definition for brickearth/ brick earth:

brick earth n.  Earth or clay suitable for making bricks. Now chiefly in form brickearth. A fine grained silty deposit consisting of or derived from loess, occurring in the Thames basin and other parts of southern England. 

1816 W.Smith. Strata identified 11.  The Oak-tree clay also may be mistaken or confounded with the Brick earth, which in several parts produces good oak.

The famous early reference to brick-earth is that by John Evelyn the diarist, who in 1667 is involved in schemes to rebuild post-fire London in brick.

6 March 1667: I proposed to my Lord Chancellor, Monsieur Kiviet's undertaking to wharf the whole river of Thames, or quay, from the Temple to the Thames, as far as the fire destroyed, with brick, without piles, both lasting and ornamental.

26 March 1667: This afternoon I had audience of his Majesty, concerning the proposal I had made of building the quay...  Sir John Kiviet dined with me. We went to search for brick-earth, in order to a great undertaking. 

7 Sept.1667: Came Sir John Kiviet, to article with me about his brickwork.

2 April 1668: To the Royal Society, where I subscribed 50,000 bricks, towards building a college.

Evelyn lived in Deptford, on the south bank of the Thames, adjacent to Deptford Creek. He lived at Saye's Court, Deptford and it appears that he may have been planning to use local ground for his bricks.

14 Aug. 1668.  His Majesty was pleased to grant me a lease of a slip of ground out of Brick Close, to enlarge my fore-court, for which I now gave him thanks.

Actually the Evelyn brickmaking project does not go well (one suspects that Sir John Kiviet may have been less than trust-worthy) and another famous diarist comments on the endeavour:

Samuel Pepys 23 Sept 1668: At noon comes Mr Evelyn to me, about some business with the office, and there in discourse  tells me of his loss, to the value of £500, which he hath met with, in a late attempt of making of bricks upon an adventure with others, by which he presumed to have got a great deal of money; so that I see the most ingenious men may sometimes be mistaken. 

After the Great Fire of London there was a huge increase in brick production because it was ordered that London should be rebuilt from non-combustible materials. The Company of Tylers and Bricklayers had kept some control on the world of bricks but this proved impossible to maintain after the fire and widespread brick manufacture developed. And, of course, the fates had placed, in the Thames basin, a large amount of loess material (to become eventually known as brickearth) which could be turned into excellent bricks- assisted by a great post-fire discovery.  

Useful reference: T.P.Smith 2007. 'Upon an adventure with others' John Evelyn and brickmaking after the Great Fire of London. British Brick Society Information 103, 10-15.

According to the Company of Tylers and Bricklayers in 1714 it was not until after the failure of the Evelyn Deptford brickyard that a new method of brick masking was discovered.. Here one of our questions might be answered. When was it discovered that adding rubbish to the brickclay made brickmaking in Kent & Essex extra profitable? A virtuous network was established with a great and expanding city needing an endless supply of bricks connected by a convenient river to large deposits of ground material which proved ideal for brick making. And the city waste provided fuel for firing the bricks and enabled the transport barges to be loaded in both directions of travel. The discovery of the useful combustible admixture appears to have been made by accident.

" the practice of using ashes commonly called spanish (was) begun about forty years since [hence not until early 1670s] occasioned by diging up several fields contiguous to the city after the great fire which fields having been much dunged with ashes it was observed the bricks made with earth in those fields would be sufficiently burned with one half of the coles  commonly used. "

Why was the admixture called Spanish?  Here is one of the great brickearth questions. Loessic brickearth + Spanish makes fine bricks; but why is Spanish so-called?  And have our investigations exposed an error in the OED? 

OED 1714 London Gazette no.5209/4.  Together with two stools of Brick-Earth ready dug and spanished.

OED definition: etymology- of obscure origin; obsolete, rare. Earth or clay unfit for brickmaking.

This definition is wrong; it should read- rubbish or waste material added to brickearth to improve the efficiency of the firing process. OED suggests that Spanish is a bad thing but the opposite is true. Spanish is useful and virtuous in brickmaking with Thames brickearths (aka loess).

Daniel Defoe (yet another journal keeper of the time ; see in particular Journal of A Plague Year- not 2020 but 1665) casts a useful light on Spanish.

Daniel Defoe:  A brickmaker being hired by a Brewer to make some bricks for him at his country house, wrote to the brewer that he could not go forward unless he had two or three loads of Spanish, and that otherwise his bricks would cost him six or seven chaldrons of coals extraordinary, and the bricks would not be so good and hard neither by a great deal, when they were burnt

There ensues some misunderstanding because the brewer understands spanish to be liquorice juice.

Defoe was writing in 'The Complete English Tradesman'(1726) and he was making a point about clarity in communication. Chaldron was a volume measure, maybe about 32-36 bushels; Newcastle coal about 2850-2978 lbs; 1.309 cubic metres..

Defoe again:  the brickmakers all about London, do mix sea-coal ashes, or laystal-stuff, as we call it, with the clay of which they make bricks, and by that shift save eight chaldrons of coals out of eleven, in proportion to what other people use to burn them with, and these ashes they call spanish.

Laystal: a place where rubbish and dung are deposited. 

OED 1725 Act 12 Geo I c.35.  Several persons.. continue to make bricks of bad stuff and unsizeable dimensions, and do not well burn the same, and in making thereof mix greate quantities of soil called Spanish.  In other words too much Spanish and not enough brickearth, but the spanish properly used is a valuable ingredient. Spanish begins to be used after the great fire and contributes to the exploitation of the great brickearth deposits of Kent and Essex. And they were great deposits- hidden by history and industry were very large deposits of loess material which was used in the construction of a large brick city. Eventually brickearth will come to mean the deposits in Kent and Essex, and the loessic brickearth will come to be differentiated from brick clay in general.

The Smeed Dean brickworks in Kent was said to be the largest in the world; 60 million bricks were made in 1877. The loess deposits being exploited were of considerable size and thickness but because they had largely been mined away before loess science developed tended to be somewhat neglected and under-appreciated. These bricks were made with the aid of the added ashes and cinders, the spanish, and the history of the spanish could be a topic for further exploration. The ashes and cinders from houses all over London were collected into vast heaps and accumulations, and the trade in these materialsdependent on the brick making industry, provided a source of much economic activity. 

The last complete book by Charles Dickens, Our Mutual Friend 1865, relates largely to a large heap of spanish which serves to provide the monetary fortune for some of the protagonists. The picture by E.H.Dixon 1837 shows a large dust heap in the Kings Cross area.

 

Useful reference: Richard Hernry Horne 1850. Dust or ugliness redeemed.  Household words 1, 379-384.  The brickmakers at Uxbridge would contract for 15 or 16 thousand chalrdons of cinder-dust.. Brickmakers all around London relied on the constant supply of spanish and on the vast resources provided by the brickearth deposits.

Another dust heap picture; this time by C.H.Matthews

Questions 2: scientific

Where did all that brickearth/loess come from, and how was it emplaced? It appears that the story of the English loess is complicated and involves many steps and events.

The chart shows the route to the bricks. The chart (constructed by Colin Bunce) shows events and stages on the journey from the initial loess particles to the bricks made by Smeed Dean. It follows the old PTD (1966) scheme and indicates formation events, transportation events and deposition events (hence P, T and D). The D2 event puts loess all over SE England; subsequent events move this material about to give the deposits and concentrations that we observe. The large drainage basin is the Thames basin and material falling therein is eventually concentrated in the Kent and Essex brickearths. The Kent brickearth is augmented by material from the Medway basin.

Loess material in SE England; it has been suggested that it is the concentration of loess material in SE England that accounts for the concentration of brick buildings in SE England.

Useful reference: Smalley, I.J. 1986.  The nature of brickearth and the location of early brick buildings in England.  British Brick Society Information 41, 4-11.