A first Holocene leaf wax isotope-based paleoclimate record from the semi-humid to semi-arid south-eastern Caucasian lowlands

The Holocene paleoclimate of the Caucasus region is rather complex and not yet well understood: while existing studies are mainly based on pollen records from high-altitude and humid lowland regions, no records are available from the semi-humid to semi-arid south-eastern Caucasian lowlands. Therefore, this study investigated compound-specific δ2H and δ13C isotopes of leaf wax biomarkers from Holocene floodplain soils in eastern Georgia. Our results show that the leaf wax δ2H signal from the paleosols mostly reflects changes in the moisture source and its isotopic composition. Depleted δ2H values before ~8?cal ka bp change towards enriched values after ~5?cal ka bp and become again depleted after ~1.6?cal ka bp. This trend could be caused by Holocene changes of the isotopic compositions of the Black and eastern Mediterranean Sea, and/or by varying contribution of both moisture sources linked with the North Atlantic Oscillation. The leaf wax δ13C signal from the paleosols directly indicates varying local water availability and drought stress. Depleted δ13C values before ~8 and after ~5?cal ka bp indicate wetter local conditions with higher water availability, whereas more enriched values during the middle Holocene (~8 until at least 5?cal ka bp) indicate drier conditions with increased drought stress.Introduction Materials and methods - Study area and climate setting - Studied section - Analytical procedure Results Discussion - The δ2H signal - The δ13C signal Conclusion

Distribution of Chernozems and Phaeozems in Central Germany during the Neolithic period

A well-based knowledge about the former distribution of Chernozems and Phaeozems is necessary to (i) better understand the factors influencing formation and degradation of these highly fertile soils, and (ii) better explain prehistoric settlement patterns that were also determined by natural factors such as soil fertility. During this archaeopedological study carried out in Central Germany we applied sedimentological and micromorphological methods to compare soils and pedosediments from the recent Chernozem/Phaeozem region with black-coloured pedosediments buried in early Neolithic structures of the recent Luvisol area directly to the east. Relocated clay coatings and significantly lower magnetic enhancement compared to Chernozem/Phaeozem-derived material were found in most black-coloured pedosediments in the Luvisol area. This demonstrates that despite their location next to an extensive Chernozem/Phaeozem area these sediments do not originate from Chernozems or Phaeozems. Instead, their dark colour must either originate from anthropogenic input similar to black-coloured Anthrosols (“Dark Earth”), or must stem from Ah-material of former Luvisols. Consequently, may be apart from a small relatively dry and carbonate-rich Luvisol region northwest of Leipzig there was obviously no significantly larger distribution of Neolithic Chernozems and Phaeozems in this region during the past. Consequently, the regional early Neolithic settlers of the Linear Pottery Culture settled intensively also in areas outside the distribution of Chernozems and Phaeozems, and the activities of these settlers did not lead to the formation of such soils. Thus, fertile soils were obviously only one factor among probably others to explain the regional Neolithic settlement pattern. Significantly lower carbonate contents were found for the parent material of the black-coloured pedosediments in the Luvisol region compared with the parent material of Chernzems and Phaeozems. This demonstrates that the decisive factor to explain the recent and former spatial distribution of Chernozems and Phaeozems in this relatively dry area is the carbonate dynamics. Anthropogenic activity since the early Neolithic period obviously helped to preserve the naturally formed Chernozems and Phaeozems by re-carbonatization processes, but humans were not the main soil forming factor in early settled regions

Climate forcing and shifts in water management on the Northwest Arabian Peninsula (mid-Holocene Rasif wetlands, Saudi Arabia)

The mid-Holocene climate of Northwest Arabia is characterised by a significant increase in aridity which gave rise to changes in water management strategies including sophisticated techniques at later stages. The Rasif site, situated in Northwest Saudi Arabia, reveals a Late Neolithic society with multi-roomed domestic structures (1st phase, 6th millennium BCE, before the current era). At Rasif site the sediments of an endorheic basin (qa) show a minimum in salinity during this 1st phase. The 2nd phase is characterised by a pastoral ‘Chalcolithic’ watering and ‘Chalcolithic’ burial location of the 5th millennium BCE with wells, complex trough systems, and initial, probably coexistent grave structures. During this 2nd phase the qa deposits show already a slight increase in salinity. We have evidence for a sub-surface water-rich sand layer within the qa that was exploited by shallow wells. During the subsequent 3rd phase the number of pastoral ‘Chalcolithic’ D-shaped grave structures within the qa increased, probably co-existing with deepened wells and complex trough systems. At that time the qa is covered by an almost impermeable saline clay layer. The 4th phase is characterised by a culturally yet to identify pastoral post-‘Chalcolithic’ watering location with single small troughs. The final 5th phase represents a culturally unidentified pastoral post-’Chalcolithic’ to sub-recent water harvesting location with complex dam systems, which were probably modified numerous times. The dam systems allowed to flooding the qas for several months, providing (sub-) surface water in the nowadays Northwest Arabian desert

The evolution of Saharan dust input in Lanzarote (Canary Islands) - influenced by human activity in the Northwest Sahara during early Holocene?

An overall Holocene increase of Saharan dust input to the Canary Islands and to the North Canary Basin is accompanied by a strong coarsening of Saharan dust in loess-like sediments deposited on Lanzarote from ~7—8 ka. No similar coarsening events are indicated in investigations of the sedimentological record for the last 180 ka, a period showing several dramatic climate changes. Therefore a mobilisation of Holocene dust by anthropogenic activity in the northwest Sahara east of the Canary Islands is assumed. Although scarce archaeological data from the coastal area of that region does not point to strong anthropogenic activity during the early Holocene, a high density of unexplored archaeological remains is reported from the coastal hinterlands in the Western Sahara. Thus, the hypothesis of early anthropogenic activity cannot be excluded