Thursday 20 December 2018

Loess & Society: the Indus Valley civilizations ~3000 BCE - 1500 BCE.

The Chinese society grew, developed and flourished in the loess regions associated with the eastern parts of High Asia. This was/is the most impressive and longest lasting of the ancient civilizations and it can be argued that it owes much of its success to its firm foundation in the loess lands. There were/are loess lands associated with the western end of High Asia; not so spectacular and amazing as the Chinese occurrences but significant and deserving of appreciation. The Central Asian loess has been studied and investigated but the loess now in India and Pakistan has been neglected and its societal influence has not been fully appreciated. The Indus Valley was the home for well developed societies in the period of around 3000-1500 BCE; two centres are identified: Harappa and Mohenjo Daro and they both appear to have interesting loessic connections. Here were well developed societies with brick buildings, built with fired bricks, and an alphabet or writing system, which still needs to be significantly translated.

Some of these symbols appear to have geomorphological significance. There are four major rivers in the Punjab- the Jhelum, Chenab, Ravi & Sutlej dominate the region, and are closely associated with the Harappan society. The better known Mohenjo Daro situation is located further down the Indus Valley. The loess deposits in the Indus Valley are not well demarcated; there has not been much mapping activity, but the two deposits indicated by S.Z.Rozycki correspond nicely with the two sites of ancient societies

.
Region 7 on the High Asia diagram is where we find the Indus Valley civilizations; region 1 is the Central Asian loess region; the two rivers indicated are the Amu-Darya and the Syr-Darya. Regions 3 & 4 contain the Chinese loess deposits.

S.Z.Rozycki  1991.  Loess and Loess-like Deposits. Ossolinium Wroclaw. On p.117 in the section on Local Loesses of Southern Asia - one of the very few maps of loess in India region. SZR has made the picture rather too complex but he manages to show the two loess regions: NE of the Thar desert and W of the Thar desert; the locations of the Harappan and Mohenjo-Daro civilizations.

 Bricks. Thoughts about bricks. The Indus Valley people built with fired bricks; and they built extensively- there was a lot of brick construction in Harappa and Mohenjo Daro. So they must have had good access to large deposits of suitable brickearth- the sort of brickearth that encouraged the making of fired bricks. It has been suggested that the location of early brick buildings in England was to some extent controlled by access to loessic brickearth- for the construction of suitable bricks. Similar constraints could apply in the Indus Valley; city location may depend on the provision of material for making bricks. In the case of Mohenjo Daro the city appears to be placed exactly on the loess region demarcated by Rozycki. A large patch of suitable loess providing building material for a substantial city. And there must have been plenty of wood available; we see the bricks being fired in clamps with wood as the fuel. A lot of bricks requires a lot of wood.

The bricks were made to a 4:2:1 ratio; the sizes were 10 x 20 x 40cms or 7 x 14 x 28 cms. These are large bricks; the smaller bricks appear to been used in houses and the larger bricks in public buildings. They were well laid and many of the constructions have lasted remarkably well.


The question of the big brick.
Reports suggest that fired bricks were used to construct the buildings at Harappa and Mohenjo Daro. Also it is suggested that some of these were very large- the big bricks 10 x 20 x 40 cms; far too large to be conveniently handled. The normal European brick in the 21st Century has dimensions of about 6 x 10 x 21 cm. It is designed to fit the hand of the bricklayer, and also be of a weight which he or she can lift and manipulate.
To be able to produce, to move, and to construct with these large bricks suggests a very well organised and efficient society. The number of bricks used in Harappa and Mohenjo Daro is enormous- so vast brickearth resources were required, and large amounts of fuel for firing. But it is the size of the large brick which causes questions. It is too big; it requires two people to handle it- particularly in the unfired state; great skill and dexterity would have been required. And to get satisfactory firing.. difficult.


Are the reports perhaps mistaken? The reported smaller Indus Valley brick at 7 x 14 x 28 cm is not that much larger than the standard European brick and would seem to have been a logical size for normal use. We need a brick measuring expedition to the Indus Valley to measure the bricks, and try
to locate the regions where they were produced.

Tuesday 4 December 2018

Four Soviet Loess Laboratories

The Soviet Union was dismantled in 1990 and a widespread network of loess investigation and loess research vanished with it. In 1988, very close to the end of the Soviet period M.Yu.Abelev, a senior investigator, addressed a conference in Beijing, on loess in the USSR. He described the world of loess geotechnology, probably unaware that the end-times were so close. He recorded that 30,000 people in the USSR were concerned with the problems of research into the properties of loess and the development of methods of construction on loess soils. This seems like an incredibly large number but, back in 1988, there was a large amount of loess territory under Soviet control.

Abelev listed some interesting geography: loess soils constituted more than 14% of the total territory of the USSR. Such soils were widely spread over the territory of the whole Soviet Union to the south of the 60N latitude. They occupied more than 80% of the territory of many of the union republics such as the Uzbek SSR, Tadzhik SSR, Kirghiz SSR, Ukrainian SSR, Moldovian SSR and Azerbaijan SSR. Loess soils were also encountered in the Georgian SSR, Kazakh SSR and in quite a few regions of the RSFSR. A great many residential buildings in cities and towns and big industrial enterprises were being erected on loess. In many buildings and structures erected in the 1920s and 1930s deformations developed and failures sometimes occurred. Post- 1930 in the USSR under the supervision of Professor Yu.M.Abelev (1897-1971; father of M.Yu.Abelev) special research laboratories and production institutes were founded which were concerned with the research and development into reliable methods of construction of industrial and civil structures on loess ground.
New laboratories concerned with investigations into the properties of loess were set up in Kiev, Tashkent, Baku and Dnepropetrovsk; the four Soviet Loess Laboratories. Now, 30 years after Abelev delivered his paper, the quondam-loess of the USSR is in separate new countries and the all union loess network is broken.

2 references
Abelev, Yu.M. ,Abelev, M.Yu. 1968.  Fundamentals of design and construction on collapsible marcoporous ground.  Izdatel'stvo Literatury po Stroitel'stvu, Moscow 2nd.ed (this 2nd edition is probably better than the 1979 3rd edition- certainly cartographically).
Abelev, M.Yu.  1988/1989.  Loess and its engineering problems in the USSR. in Engineering Problems of Regional Soils (International Conference Beijing 1988) ed.CCES, Pergamon Press, Oxford, pp.3-6

Some additional material from V.I.Krutov:
[Krutov, V.I.  1987.  Foundation construction on collapsible soils. Soil Mechanics & Foundation Engineering 24, 219-223.]

Collapsible soils ~10% USSR territory; recent (1989) construction 30%- in the regions intense construction activity.  Problems arose in the 1920s with irrigation systems in Central Asia and the North Caucasus, and oil industry construction at Grozny.  Then the first 5 year plans, large metallurgical and machine manufacturing plants in Zaporozhe, Nikopol, Dneproptetrovsk, Zhadanov, Kherson and Kuznetsk, also irrigation systems and hydraulic structures in Central Asia, the N. Caucasus, & Transcaucasia.

Post-war years: largest industrial structuresd: VAZ, KamAZ, Atommash, KZTE etc.  Residential and industrial construction in Ukraine, the Rostov region, Siberia & Central Asia,

First solutions to foundation problems by Yu.M. Abelev (1931). Later contributions from M.Yu. Abelev, V.P. Anan'ev, Kh.A. Askarov, L.G. Balaev, Ya.D. Gil'man, V.N. Golubkov, M.N. Goldstein, A.A. Grigoriyan, N.Ya. Denisov, S.N. Klepikov, A.A. Kirilov, N.I. Kriger, A.K. Larionov, I.M. Litvinov, G.M. Lomize, G.A. Mavlyanov, A.A. Musaelyan, A.A. Mustafaev, N.A. Ostashev, A.L. Rubinshtein, E.M. Sergeev, V.E. Sokolovich, R.A. Tokar' & N.A. Tsytovich.

afterword from Osipov & Sokolov
[Osipov, V.I., Sokolov, V.N. 1995.  Factors & mechanism of loess collapse. in Genesis & Properties of Collapsible Soils. ed. E.Derbyshire, T.Dijkstra & I.J.Smalley. NATO ASI series 468, Kluwer]

55 cities & towns in Russian regions affected by loess collapse; 3.5 million km2 in area. They list 6 relevant books:

Anan'ev, V.P. 1964. Mineralogical composition and loessial soils properties. RGU Rostov-on-Don 218p.

Balaev, L.G., Tsaryev, P.V. 1964.  Loessial soils of Central & Eastern Pre-Caucasus area. Nauka Moscow 248p.

Kriger, N.I.  1965.  Loess, its properties & relation to the geohgraphical environment.  Nauka Moscow 296p.

Krutov, V.I. 1982.  Bases and foundations on collapsible soils. Budivel'nik Kiev.

Larionov, A.K. 1971.  Research methods of soil structures.  Nedra Moscow 168p.

Sergeev, E.M., Larionov, A.N., Komissarova, N.N. eds.  1986.  Loess in the USSR.

 

Monday 15 October 2018

Planning to cope with tropical and subtropical climate change

Review & Commentary; this is not the most loessic of books but the topic is very important and this impressive volume deserves a Loess Ground mention.

Planning to Cope with Tropical and Subtropical Climate Change
Editors: Maurizio Tiepolo, Enrico Ponte, Elena Cristofori
Publisher: De Gruyter Open, Warsaw & Berlin, 380p

The book is a collection of case studies in subtropical and tropical zones and considers different types of cities: large (over 1 million population), intermediate (0.1-1 million population), secondary (less than 0.1 million population). There are three sections: hazard, adaption planning and best practices.

Overall, 12 contexts are explored: large cities (Dar es Salaam, Niamey), intermediate cities (Caraguatatuba, Taberre, Zurich), secondary cities (Mekhe, Pragatinagar, Nawalparasi) and regions (Catalonia, Chaco, Gaza province, Piedmont, Reunion, Tillaberi). With the exception of Zurich, the case studies are divided equally between subtropical and tropical zones according to the Koppen-Geiger classification after the categories and subcategories studies of Trewartha.

Friday 28 September 2018

Dust in Sydney (TG etc)

A paper we should take note of:
Aryal, R., Kandel, D., Acharya, D., Chong, M.N., Beecham., S.  2012.
Unusual Sydney dust storm and its mineralogical and organic characteristics.
Environmental Chemistry 9, 537-546

The dust storm was in 2009 and affected Sydney and Brisbane. Aryal et al (2012) did a thorough study on the dust material, and revealed four particle mode sizes: 0.6, 4.5, 9.3, 20 micrometrres.

The investigators made a neat use of thermogravimetric analysis- we do not see enough TG usage and this application is very welcome. TG revealed an organic content 10.6%. They only report a TG curve, it would have been very useful if they had produced a DTG curve. Their TG curve appears to contain various interesting events.


Our TG reproduction is much better than the original; in the original paper the figures are very small and relatively indistinct. Fig.7 is full of suggestion- a DTG picture could have been remarkably interesting.
The authors concluded that the particles contained Si, Al and Fe in oxide form in which the Al/Si ratio was 0.39. The high organic content and the Al/Si ratio indicated that the particles orginated from agricultural land as well as desert.

Thursday 13 September 2018

Thermogravimetric Analysis of Problem Soils (including Loess)

Thermogravimetric Analysis (TG) is an analytical technique in which the change in weight of a sample is measured as the sample is heated. It is widely used but it is not a popular technique; it is neglected in soil engineering and in engineering geology and (in fact) in all of the earth sciences.

Figure 1 is by George Xidakis (from Smalley & Xidakis 1979) and shows a result for the Modbury Clay (from South Australia; the Modbury High School suffered considerable damage from shrink-swell effects). This sample from CSIRO was analysed on a Leeds University TR02 thermobalance and the result is presented as derivative curves. Fig.1 shows the change in rate of weight loss as samples are heated from room temperature to 800 degrees.

Smalley, I.J., Xidakis, G.S.  1979.  Thermogravimetry of an expansive clay from Adelaide: approximate mineralogical analysis using standard montmorillonites  Clay Science 5, 189-193.


The great advantages possessed by the Stanton-Redcroft TR02 thermobalance were the ability to take quite a large sample, say 1-2 g of soil; a slow rate of heating; results presented in a way to facilitate careful graphical analysis. But the machine did not match the times- by the time the potential of TG techniques in soil engineering had been realised the age of the large sample thermobalance was over. The market required small sample machines for routine analysis which could provide quick heating and cooling. The potential of the large sample thermobalance was never realised- the time might be right for a revival of ground-targeted thermogravimetry.

The pioneering paper was probably Coleman et al (1964) on red soils from Kenya, although the TG applications were not emphasized. The dehydroxylation reaction is very marked in kaolinite (a 1:1 clay mineral) so the kaolinite development in the red soils and laterites of Africa and South America made TG a useful tool. But the first, and most impressive application of TG to a problem soil was in the investigation of the very sensitive post glacial clays of extreme sensitivity (the so-called quickclays).

Coleman, J.D., Farrar, D.M., Marsh, A.D.   1964.  The moisture characteristics, composition and structural analysis of a red clay soil from Nyeri, Kenya.  Geotechnique 14, 262-276.


Fig.3 is the derivative plot for the St.Jean Vianney clay. SJV was the site of a significant quick clay landslide (several killed, much damage) and this resulted in much investigation of the ground material. The SJV DTG plot is quite complex. A1- adsorbed water: a small peak- the clay minerals are of the inactive nature. The equivalent peak for the Modbury clay is large, the Modbury clay is dominated by smectite type clay. B2 organic material; C1 dehydroxylation reaction- but muted, not a large amount of an inactive 2:1 clay mineral; D carbonate breaks down to CaO + CO2. This particular result showed that there was a small amount of clay mineral material in the SJV clay, the ground material was not really 'clay' - the SJV clay was dominated by clay-size primary minerals; the clay minerals played a relatively small role in determining the properties. The sensitivity was not due to clay mineral content.

Smalley, I.J., Moon, C.F., Bentley, S.P.  1975.  The St.Jean Vianney quickclay. Canadian Mineralogist 13, 364-369.


This is a particularly satisfying picture from Smalley et al 1975. This is the SJV quick clay (note the alternative terminologies- there was a move to call the quick clays quickclays to show that they were distinctive materials- to detach from the clay label)  2 g samples showing -at point C - the dehydroxylation reaction of the inactive type clay- probably illite. The carbonate peak is well defined- a beautiful piece of analytical architecture.

TG/DTG techniques were appreciated in Hungary; a whole series of standards was produced and published as loose-leaf cards. (see G.Liptay 1971  Atlas of Thermoanalytical Curves, Akademiai Kiado Budapest). Card 123 was Potassium Hydrogen Phthalate: recommended for use as a thermal standard.

 

Thursday 31 May 2018

The heavy bombardment model for the formation of clastic material on Mars

Loess on Mars?- we keep looking but loess does not appear. It appears that no mechanism operates at the Martian surface which can produce the silt-sized particles necessary for the formation of a loess deposit. The granitic crust and some vigorous geomorphology ensured that the Earth was well supplied with sand sized quartz particles and silt sized quartz particles; the essential ingredients for sand dunes and loess deposits. Mars appears to have an essentially basaltic crust and we are faced with the difficult problem of finding a particle forming mechanism.




Speculation: the last major particle forming events occurred on Mars at the time of the Late Heavy Bombardment, i.e. about 4 billion years ago. These are old particulates- but maybe old particulates can exist at the Martian surface. If there are no internal lithological controls in Martian crustal rocks then an energetic particle forming event should produce a range of particles. On Earth there are internal controls and this tends to give a marked modality in clastic material (in particular sand and silt). So-very large clasts down to very fine dust. Dust due to crushing and abrasion at the impact events, and lasting for billions of years because no lithological processes converted it into anything else. The dust is very old.  Sand sized debris can go to make the Martian dunes. Large & very large clasts can litter the Martian surface, as the mechanical explorers reveal.

This range of impact particle sizes should contain some 'loess' sizes, but probably not enough to form a proper modal deposit. The loess ages on Earth are measured in thousands, perhaps millions of years; the aerosolic fine dust is probably recent material- is it reasonable to expect very old, very fine particulates on Mars?  Given the age of the Martian surface one might expect more particulates; if there was essentially one particle forming event a very long time ago this might explain the relative paucity of particulate matter.

Saturday 14 April 2018

The History of INQUA- for XX INQUA Congress

Many years ago there was talk about the preparation of a detailed history of INQUA (the International Union for Quaternary Research) but nothing seems to be happening; no materials are appearing. In the interim, and in time for the XX INQUA Congress in Dublin in 2019, here is a link to a short history of INQUA- available online thanks to Michigan State University.

Notes for a history of INQUA- the International Union for Quaternary Research (Association pour l'etude du Quaternaire, Internationale Quartarvereinigung, etc.  2011. Ian Smalley. Loess Letter 65 (ISSN 0110-7658) online at www.loessletter.msu.edu

The INQUA Loess Commission provided additional historical data and the doings of that particular Commission are fairly well recorded:

Smalley, I.J., Markovic, S.B., O'Hara-Dhand, K. 2010.  The INQUA Loess Commission as a Central European enterprise. Central European Journal of Geosciences/ Open Geosciences 2, 3-8.

Smalley, I.J., O'Hara-Dhand, K. 2010.  The Western Pacific Working Group of the INQUA Loess Commission: expansion from Central Europe. Central European Journal of Geosciences/ Open Geosciences 2, 9-14.


Smalley, I.J., Howarth, J., Nugent, H.  2011.  The INQUA Loess Commission goes from Budapest to Beijing, and then returns to Europe (1991-2003).  upload to Scribd.com

 

Wednesday 11 April 2018

Fragipans & Loess [part 2]

Loess & fragipans: Development of polygonal-crack-network structures in fragipan horizons in loess ground.  I.J.Smalley, S.P.Bentley, S.B.Markovic 2016.  Quaternary International 399, 228-233

What have we here?  This highly speculative figure purports to show possible contacts in an ideal loess soil. Some of these contacts allow collapse, some are less collapsible. Collapse does seem to be a key aspect of fragipan formation. Deformation processes play a role in fragipan formation in various ways (a) initial collapse (b) shrinkage causing the development of a polygonal crack network (which is a defining aspect of Fragipans in Soil Taxonomy).



 Fragibutt structures in the coastal Fragic Pallic Soils; SI NZ. This exposure is at Normanby, near Timaru. The figure comes from: Berger, G.W., Pillans, B.J., Tonkin, P.J.  2001.  Luminescence chronology of loess-aleosol sequences from Canterbury, South Island, New Zealand.  New Zealand J. Geology & Geophysics 44, 501-516. Scale bar 10cm.

 Fragic Pallic Soils;  South Island New Zealand. 

Monday 9 April 2018

Fragipans in Loess

A fragipan is a soil horizon (often Bx).  Fragipans form in silty soils, they form in loess- in fact one wonders if the fragipan in the loess is the true fragipan and all others are in some way faux fragipans. The reason for this statement is that loess is the system that starts out with a low packing density- and acquiring a higher packing density appears to be a requirement for fragipan formation.

Look at this fig. of fragipans in the USA- this is from Bockheim & Hartemink (Catena 104, 233-242, 2013)  the fragipans favour the east, where rainfall is higher- needs to exceed evapotranspiration for efficient fragipan formation. Loess country is highlighted.
There is said to be a continuing discussion about the mode of fpan formation. Two angles are explored (a) the physical angle- which requires the necessary densification to be produced by hydroconsolidation, and (b) which requires fpan properties to develop chemically, movements of ions and substances in the soil system are involved.
There appears to be macro-movement in the fragipan system. Movement of silt sized particles is involved, first to collapse to the required density, and then to respond to drying forces and develop the characteristic prismatic structure. There does not seem to be any chemical explanation for the formation of the prismatic structure (noted by John Hardcastle in the first description of fragipans in 1890). Look at the sketch by Van Vliet & Langohr (reproduced by Smalley Bentley Markovic 2016 QI 399, 228-233):

this shows the prismatic structure rather nicely. When the system collapsed there is excess water (pore volume has decreased) as water leaves contraction stresses develop and characteristic polygonal crack pattern ensues.
It is possible that the fragipan discussion is now in a situation that the loess discussion used to be in. Once upon a time there were two approaches to loess deposit formation (a) physical- the material was brought by wind and deposited to form an open packing, and (b) chemical- the classic Bergian in-situ idea where loess formed by weathering and soil formation processes; by the movement of chemicals. Now- bits of the Berg idea remain and are useful and have been incorporated into modern loess lore but nobody denies that loess deposit formation is an aeolian event- and that this aeolian event delivers many of the defining properties. Moving silt sized primary mineral particles is critical for loess deposit formation. Moving silt sized primary mineral particles might be critical for fragipan formation- the chemistry may be interesting but incidental. The major properties of fragipans could be explained by structural collapse via hydroconsolidation, and prismatic structure formation via drying stresses.
The ideas appear to fit a loess system; what about non-loess fragipans?. Perhaps there are no non-loess fragipans- just fragipan-like horizons? 

Examine the map of fragipans in Eurasia- some interesting looking occurrences in NW Italy- but not a lot of fragipan records.



Sketch from thesis by G.L.Scott University of Canterbury 1979 showing fragipan situation in the loess at Banks Peninsula. The fragipan relates well to the surface; the sketch offers good support for the Bryant hypothesis of fragipan formation.