In periods of dense cover by vegetation or under stable geomorphic conditions sedimentation rates may decrease or even come to a temporary stop; during such periods soils form. For example, successions of slope deposits may contain intercalated buried soils; they are typical archives reflecting climatic-geomorphologic-environmental responses. Buried soils in such successions are recording phases of relative stability of the land surface; each sediment layer burying a soil indicates an event or episode of slope instability due to climatic forcing or tectonics (e.g., on escarpments or scarps). In loess and loess-like deposits, cycles of sedimentation and soil formation indicate increased or decreased deposition of dust (sometimes directly related to dust formation and transport); mostly in response to shifts in regional or global climates. Thus, various types of sediment-soil successions are useful archives for identifying stratigraphic hiatuses, duration of hiatuses, tectonic quiescence, causal climatic variations, environmental changes, and vegetation type and density responses. In some cases, compounds of buried soils (such as soil organic matter or pedogenic carbonates) can be dated and analyzed for their isotopic composition. These data provide valuable information regarding environmental conditions in specific time windows. Complex soils on stable landforms can also provide data regarding environmental and climatic conditions especially in hyper-arid regions. However, relationships between the duration of soil development and progressive changes in soil properties with time on one hand, and local and regional climate on the other hand, must be understood.

International interaction between scientists dealing with different aspects of such soil-sediment successions is needed; many scientists in different parts of the world are facing similar problems in diverse environments when using soils, buried soils and paleosols as indicators of landscape history. Therefore, an international focus group that will bring together researchers working on soils in the frame of Quaternary research will be highly fruitful. Such a group will promote reconstruction of Quaternary landscape history of various regions and will share, improve and develop new methods and new knowledge on dynamics, rates and duration of soil formation.

2. Tasks and objectives
     2.1 Tasks
As mentioned above, the main aim of the focus group is improving the knowledge on the relationship between observed and analysed pedogenic properties in soils or paleosol on one hand and the climate conditions and time span of tectonically and geomorphologically stable periods on the other hand. Against the background of this main aim two projects are proposed to start with. The two projects will focus on the following major tasks:

          2.1.1. Project RAISIN:
Rates of soil forming processes in different climates, obtained from soils and paleosols in settings where climatic conditions and duration of soil development are wellknown:

The main tasks of this project will be to review, compare and summarize published and new studies on rates of soil forming processes. Based on this synthesis of research results, general rules of soil formation rates under defined climatic conditions will be obtained. These studies will be associated with development of dating methods, application and testing of existing methods. The outcome of this work will be useful for any earth scientist interpreting Quaternary continental sequences, evaluating geomorphological and environmental stability, weathering rates, dust influx in soils, and chronologies.

          2.1.2 Project AEOMED:
Loess deposits and aeolian additions to current surface soils and paleosols in Mediterranean climates:

Aeolian additions to soils represent a primary pedogenic process in soil formation in general and in soil formation under Mediterranean climates in particular. The main task of this project will be the evaluation and quantification of long-term proximal and distal eolian contribution to soils in hyperarid, arid and semi-arid areas around the Mediterranean Sea. This will contribute to the understanding of erosion rates, soil development on different parent materials under Mediterranean climatic conditions and their spatial and temporal variation. Analyses of sandy and loessial soils and paleosols around the Mediterranean will advance the understanding of glacial-interglacial environment in this region.

     2.2 Objectives
In the past decades significant progress has been achieved in evaluating the rates by which soil forming processes proceed, using mostly surface and buried soil chronosequences. These available datasets form the base to utilize paleosols as chronometers of duration of periods of land surface stability. Numerous soil chronosequence studies have been carried out in various regions, but have not yet been reviewed compared and brought to a synthesis. The particular value of such studies is that they can be used for obtaining mathematical equations reflecting soil development by plotting age-dependent soil parameters (e.g. Fed/Fet ratio; soil development indices) against time.
One objective of the focus group is thus to produce a synthesis of existing results on rates of soil formation in different climates in order to establish a present state of knowledge. This present state of knowledge will be made available for the scientific community through publication in a Quaternary International Special Issue.

In some regions establishing such soil chronofunctions is complicated by considerable influence of syn-pedogenic aeolian input on soil development. Especially in Mediterranean regions aeolian input plays a major role. It ranges from minor amounts of aeolian material mixed into the upper parts of soils to thick deposits of loess and loess-like or sandy sediments. The importance of aeolian input in Mediterranean areas has been repeatedly addressed in literature. However, a systematic documentation of type, thickness and extension of aeolian deposits and associated soils around the Mediterranean (like e. g. the one by Haase et al., 2007, on loess distribution in Europe) is still missing.
A second objective of the focus group is hence to document the present state of knowledge on the type, thickness and extension of aeolian deposits and associated soils around the Mediterranean and make it available to the scientific community.

Paleosols and complex soils may contain various pedogenetic components convenient for obtaining absolute ages and isotopic signatures. Soil organic matter has been used for radiocarbon dating for decades. In addition, radiocarbon dating has been extended successfully to pedogenic carbonates. There is obviously a great potential of this method for detailed reconstructions, particularly of pedogenic laminated carbonate. U-series have great potential for dating carbonates as well as ferruginous and siliceous pedogenic components. However dating pedogenic features requires a high degree of understanding of the parent material (especially in the case of soils developed in sediments) and of the pedogenic events and processes that are dated by these methods, which has not yet been achieved in all cases.
A third objective of the focus group is to review the present state of the art in the field of dating pedogenetic components, because multiple new approaches for dating pedogenic features have been developed in the past years.

Biological proxies such as phytoliths and other bio-opal microfossils provide information on palaeo -vegetation and- climate. Moreover, recently individual molecular components of soil organic matter indicating certain vegetation types have been isolated and used as biomarkers for palaeo-vegetation reconstruction as well as for radiocarbon dating and analysis of oxygen, hydrogen and carbon isotopes. These novel molecular techniques represent a milestone in assessing palaeo-environmental information from paleosols. Bio-indicators such as phytoliths and molecular organic components reflect the palaeo-vegetation composition in the direct surroundings of the investigated profile whereas pollen diagrams integrate vegetation over larger areas. Thus, phytoliths and molecular proxies in paleosols on one hand, and pollen on the other hand, may provide complementary information to palaeo-environmental reconstructions.
A fourth objective of the focus group is hence to document the present state of the art in the particularly rapidly growing field of biological palaeo-environmental proxies and make it available for the scientific community.

The main overall objective of the PASTSOILS Focus Group is thus to establish a solid base for interpreting paleosols in terms of duration of soil development indicating tectonically and geomorphologically stable periods. Moreover, the importance and spatial pattern of dust production, deposition and incorporation into soils in the Mediterranean region will be evaluated. The present state of the art with respect to dating pedogenic features and new molecular and isotopic methods for palaeo-environmental reconstruction based on paleosols will be reviewed and evaluated. Combining knowledge about duration of pedogenesis derived from soil properties with absolute ages from dating pedogenic features will significantly increase the potential contribution of paleosol studies for developing chronologies of Quaternary continental sedimentary records.

The focus group will provide information to the international scientific community about:
- rates of soil forming processes in different climates on similar geomorphic units
- field and laboratory methods that are useful for assessing the stage of soil development
- methods of dating various pedogenic objects
- soil stratigraphy and interpretation of soil dating
- biological proxies including phytoliths and other micro fossils as well as molecular and isotopic methods for palaeo-environmental reconstruction from paleosols
- importance and spatial pattern of proximal and distal dust deposition and incorporation into soils in the Mediterranean region.

We anticipate that interactions between scientists involved in the focus group will generate additional cross-discipline, across-environment ideas, and other stimulating research will evolve from these basic goals.


3. Number of correspondents necessary to accomplish the work of the group
An optimum size of the focus group would be about 80 correspondents, allowing for formation of task groups within the PASTSOILS group focusing on particular aspects (soil formation rates, dust incorporation in soils, isotopic studies, dating, bio-proxies etc.) that may then apply for INQUA projects supporting their work on the particular tasks.

4. Initial correspondents, including the leaders, together with a statement that those named are prepared to serve.
     4.1 Leaders
Dr. Daniela Sauer
University of Technology,
Dresden, GERMANY
E-mail: daniela.sauer@uni-hohenheim.de ; daniela.sauer@mailbox.tu-dresden.de

Dr. Rivka Amit
Geological Survey of ISRAEL
Jerusalem, ISRAEL
E-mail: rivka@gsi.gov.il

Dr. Sergey Sedov
National Autonomous University of Mexico (UNAM),
México DF, MEXICO
E-mail: sergey@geol-sun.igeolcu.unam.mx

     4.2 Initial correspondents and responsibilities