Loess near Tashkent

This is fig.10 (part of fig.10) from Scheidig 1934. This fantastic book is still a source of good things, and modified sketch maps will continue to be published. If one is allowed a little criticism it is that some of the maps are too small- so attempts at enlargement will be made.

Here we are to the west of High Asia but the classic deterministic model of loess deposit formation works well. Particle origins in the high mountains, substantial rivers for material transportation etc. The cities of Samarkand and Tashkent are emphasized on the sketch map- this is a classic loess region; many loess investigators were based in Tashkent in Soviet times and there is continuing academic interest in the region.

Most of the literature is in Russian; there is a fairly recent review:

Smalley, I.J., Mavlyanova, N.G., Rahkmatullaev, Kh.L., Shermatov, M.Sh., Machalett, B., O'Hara-Dhand, K., Jefferson, I.F.  2006.. The formation of loess deposits in the Tashkent region and parts of Central Asia; and problems with irrigation, hydrocollapse and soil erosion.  Quaternary International 152/153, 59-69.
[this paper should be accessible via the University of Birmingham website]. 

Mammoths and Loess: Mammoths on the Mammoth Steppe; & in Serbia

Mammoth in the Loess- A Study Group:  secretary- Dr Nemanja Tomic, LAPER, Faculty of Sciences, University of Novi Sad, Trg Dositeja Obradovica 3, 21000 Novi Sad, Serbia.

N.Tomic,  S.B.Markovic,  M.Korac,  N.Mrdic,  T.A.Hose,  D.A.Vasiljevic,  M.Jovicic,  M.B.Gavrilov.  2015.  Exposing mammoths: from loess research discovery to public palaeontological park.  Quaternary International 372, 142-150.

Distribution of mammoths; compare to distribution of loess lands..

R.Dale Guthrie 2001  Origin and causes of the mammoth steppe: a story of cloud cover, woolly mammoth tooth pits, buckles and inside-out Beringia. Quaternary Science Reviews 20, 549-574.
"...during the last full glacial(LGM) say 18000 BP, most of the north was unimaginably arid..  rivers were reduced to streams...  loess sheets, sand seas, dune fields and wind were common features of this aridity; therefore Pleistocene skies must have been often dusty..."

D.A.Walker, J.G.Bockheim, F.S.Chapin III, W.Eugster, F.E.Nelson, C.L.Ping  2001  Calcium-rich tundra, wikldlife and the 'Mammoth Steppe'. Quaternary Science Reviews 20, 149-163.
"These so-called Mammoth Steppes probably had the following properties (1) more fertile soils that formed as a result of the continual input of loess..."

The mammoth steppe was the habitat of the Woolly Mammoth. The Mammoth flourished in this region; it was a remarkably successful animal. Large amounts of mammoth bones have been found in the loess of (e.g) Ukraine; the mammoths had an affinity for loess terrain. Was the entire expanse of the Mammoth Steppe in effect a huge loessial plain? This was how Keilhack showed it in 1920 and the more detailed map of Scheidig 1934 shows vast loessic expanses. Current discoveries of mammoth remains are often made in the 'yedoma' soils of Siberia. It has been suggested that yedoma is a loess variant.
The Frenzel map of 1960 of loess in Eurasia covers the entire mammoth steppe and displays a widespread distribution of loess. So, what was the relationship of the mammoth to the loess. Was the loess ground the place where the best fodder grew? How did they cope with the dusty Pleistocene skies?

The Dnepr as a Loess River

The Dnepr was one of the rivers considered by Smalley et al(2009) in their review of 'Rivers & Loess'. It is the main river of Ukraine. It is essentially flowing from north to south, so it is/was transporting material in a southerly direction. The implication is a northern origin for loess material.

The Dnepr debouches into the Black Sea, as does the Danube. In the context of world rivers relative to loess a simple classification might be into (1) rivers that start in high mountains and deliver, eventually, mountain loess [with possible desert interludes], (2) rivers that start in glaciated terrain and deliver glacially produced loess material. The Dnepr is in class 2, as are the Volga and the Don.

The Dnepr delivers a 'purer' form of glacial loess than the Mississippi/Missouri system which, in the case of the younger deposits, contains mountain material from the Rockies. The mountain system delivers loess in a much more continuous manner than the glacial system which is perforce extremely episodic.

The Dnepr may be the most significant river with respect to the delivery of glacial loess; it makes a nice contrast to the Danube. The idea of the Danube as a 'loess river' has gained currency. Particle sources have been recognized, transport paths identified and deposition zones demarcated- an edifying and satisfactory picture develops. Now, can we do something similar for the Dnepr? We possibly need the Dnepr as a default glacial loess river; the Danube can serve in a similar position as the mountain loess river.

Smalley, I.J., O'Hara-Dhand, K., Wint, J., Machalett, B., Jary, Z., Jefferson, I.F.  2009.  Rivers and loess: the significance of long-river transportation in the complex event sequence approach to loess deposit formation.  Quaternary International 198, 7-18.

Loess in Ruritania: speculative geographies in a placeholder country

Ruritania is a fictional Central European country (Hope 1894, 1896, 1898).  Ruritania is also a placeholder country; this means that it can serve as a model country, an ideal country, a country or concept against which ideas or theories can be tested. A moderately recent study by Vesna Goldsworthy (1998) uses Ruritania as the model or focus for a study of literary visions of East/Central Europe. So Ruritania might be considered as an ideal geographical setting, and in particular as a visionary setting for a study, in general terms, of loess formation in Central Europe.

The placeholder idea might work well in the loess world, with loess science. We need, in loess science, a set of defining ideas. Until very recently there was considerable controversy about the mode of formation of loess deposits, and there is now some discussion about the ways in which the actual loess particles are formed. We see Ruritania as a setting for a deterministic vision of loess. In a deterministic system a set of rules will always produce the same, predictable result. So with loess we need some definite and credible ideas about making the constituent materials (essentially quartz silt formation), definition of the critical transportation modes in the early part of the deposition process- we need flood plains and aeolian transportation.

Ruritania has mountains and rivers; it is close to the Danube. It is the perfect setting for Central European loess. In the deterministic world Ruritanian mountains and rivers and the residues of glacierization must deliver loess. It is a principality; a young prince was born a short time ago, Prince George of Ruritania, and he will support the idea of Ruritania and encourage Ruritanian Studies. It is possible that some part of this deterministic landscape remains undiscovered and unexplored, there might still be tasks for field scientists crossing from Slovenia or Serbia or Moldova.

Not many landscape pictures available; the picture of Tintin entering the country shows mountains near the border. These could be the source of loess particles carried by Ruritanian rivers towards the Danube.

 

The Scheidig (1934) map of World-wide loess distribution

In 1934 Alfred Scheidig of the Saxon Mining Academy in Freiberg(Sa.) published his book 'Der Loess und seine geotechnischen Eigenschaften'. The book contained a map of worldwide loess deposit distribution (fig.5) which became and has remained the standard map of loess distribution. Now, nearly 2014, 80 years after the initial publication it is a good time for a close look at the map, and an assessment of its continuing value.
The first worldwide map is believed to be that of Keilhack (1920). This was a very simple map; it accompanied Keilhack's estimate that 9.3% of the surface of the continental crust is covered by loess. Scheidig (1934) offered considerable detail and divided loess into definite (nachgewiesen) deposits and possible/probable deposits ( wahrscheinlich oder moglich). The map was used by Woldstedt (1960) in his Quaternary treatise- it is the standard map of loess distribution. Woldstedt made a few small changes- his map comes 'mit geringfugigen Anderungen', as does our reproduction.
In 1965, for the Boulder INQUA Congress, N.I.Kriger prepared a worldwide loess distribution map. This does not compare well with the Scheidig map. Kriger chose an unfortunate base map projection; Scheidig (perhaps inadvertently) chose a good Mercator-like projection. Mercator tends to emphasize the mid-latitude zones, which is where the loess occurs. Woldstedt changed the base projection slightly- and did not improve on the original. Trofimov (2001) followed Scheidig (1934)- there has been no better version. Abelev & Abelev (1968) reproduced Scheidig (1934) as an exact reproduction.

When George met Slobodan: an important encounter in the history of loess investigation

Meetings are important. In the 1830s Karl Caesar von Leonhard met Charles Lyell in Heidelberg, and the study of loess was truly launched. KCvL had defined loess, and given it status, by including it in his book 'Charakteristik der Felsarten'(1824). KCvL showed the loess to Lyell, who in turn, included it in his book 'Principles of Geology'. The Principles had world-wide distribution, was very influential, and served to spread the word on loess.

In 1997 George Kukla met Slobodan Markovic; a meeting also with consequences. Each brought something interesting to the encounter. Kukla was a significant pioneer in loess stratigraphy and had made the exciting connection between the loess record and the data from deep sea sediments. Slobodan, in effect, brought Serbia, and thus smoothed access to what are arguably the best loess deposits in Europe. Serbian loess stratigraphy became the benchmark for European studies and provided a useful impetus to the wholesale study of loess in the Danube basin. KCvL + Lyell promoted Rhine loess; George + Slobodan promoted Danube loess.

Smalley, I.J.  1978.  Pleistocene land-sea correlations. Nature 272, 754-755  [this is about Kukla's work on loess & deep sea sediments.]
Smalley, I.J., Markovic, S.B., O'Hara-Dhand, K.  2010.  Charles Lyell from 1832 to 1835: marriage, Principles. 2 trips to Heidelberg, snails and loess.  Central European Journal of Geosciences 2, 15-18.

Loess in Ukraine: thoughts & speculations (remembering P.A.Tutkovskii)

Recent investigations of loess in Ukraine have focussed mostly on stratigraphic studies of material in the west of the country (see e.g. Gerasimenko, Lanczont, Mroczek, Jary, Markovic etc.)
Also there have been some interesting geochemical investigations which have pointed out contrasts between loess in Ukraine, and in the Danube basin (see Buggle etc) and it seems likely that loess research activity in Ukraine will increase.

The loess in Ukraine can supply a test zone for the extended and improved PTD(1966) classification of events involved in the formation of loess deposits. It now becomes the PTDC(2013) system because it has become apparent that post-depositional events are as interesting as pre-depositional events. Provenance events (P) are particle making events- the formation of the material- the absolute origin of the loess deposit formation story. P events are sedimentological events, and so are T transport events. The material is transported by rivers, often for long distances, and subsequently transported again by aeolian action. D is the deposition event, when the loess deposit assumes most of its qualities, and where pedological processes begin.

As soon as the initial aeolian deposit is formed change begins: C events occur. C is important in Ukraine because C includes chernozemisation. The black soils formed in the loess help to define Ukraine- this is Black Earth country. The ground can become more loessic during C time. It can be claimed that loess formation proceeds during C time;'Loess is not just the accumulation of dust'. P: the Ukraine loess might be classic glacial loess; Tutkovskii made the glacial connection. Examination of the large geomorphology of the system indicates that northern glaciers provided the energy for particle formation. T: a large river is in place for initial large scale particle transportation. Again the geomorphology suggests a river:deposit connection. D: classic Aeolian deposition.

C: in particular chernozemisation in the loess matrix- and remarkably substantial A horizon formation. Collapsibility can increase in the C phase. Initial collapsibility depends on the formation of a meta-stable structure in the D phase. Movement of carbonates and clay minerals in the C phase enhances collapsibility( and contributes to small scale loessification).

Smalley, I.J.  1966.  The properties of glacial loess and the formation of loess deposits. Journal of Sedimentary Petrology 36, 669-676.
Smalley, I.J.  1978.  P.A.Tutkovskiy and the glacial theory of loess formation. Journal of Glaciology 20, 405-408. 

Loess Letter 69; an issue devoted to Loess Snails. On the cover Endre Krolopp the noted Hungarian malacologist ; inside studies on Braun, Soergel and Lozek. All issues of Loess Letter now available at www.loessletter.msu.edu. If you want a hard copy contact ijs4@le.ac.uk.

High Asia and related loess deposits
A sketch map from Alekseev and Dodonov 1989

Bee-eaters in QI

This is a Northern Carmine Bee-eater
 

Loess and Bee-eaters 1 has been published in QI; the paper concerns the European Bee-eater and its interaction with loess ground. Now Loess and Bee-eaters 2 has been submitted and is about the Northern Carmine Bee-eater and its choice of nesting sites in the African loess. Actually its more about ground than birds and attempts to place the 15N loess securely in its African setting.