Wyniki wyszukiwania - BazTech

1

Earliest cereal cultivation in Egypt recorded in the Faiyum Oasis lake deposits and its palaeoclimatic context

Welc Fabian, Marks Leszek, Milecka Krystyna

Geological Quarterly

|

2023

|

Vol. 67, No. 2

art. no. 21

EN

We determine the beginning of the Neolithic farming in northern Egypt, based on analysis of core FA-1 of lake deposits in the Faiyum Oasis in northern Egypt. Regular lamination of the early Middle Holocene lake deposits, supported by radiocarbon dating and pollen analysis, indicates the earliest occurrence of domesticated cereals at ~7.8 cal ka BP in this region. The appearance of cereals in the Faiyum region was possible due to fundamental restructuring of regional climatic conditions caused by the changing atmospheric circulation in the eastern Mediterranean region. Stronger northwestern winds were accompanied by increased precipitation in winter and enabled 3 farming phases in the Faiyum Oasis at 7.8–7.6, 7.4–7.2 and 7.0–6.8 cal ka BP, separated by arid episodes with predominant southern winds. Most probably, cereal cultivation concentrated inside local wadis to the north of the lake and was rainfall-dependent. Therefore, early Egyptian farming did not develop based on irrigation systems as commonly thought, but was rain-fed, this being possible due to marked climate change at the beginning of the Middle Holocene.

2

Lateglacial-Middle Holocene stable isotope records in two coeval stalagmites from the Bihor Mountains, NW Romania

Tamaş T., Onac B. P., Bojar A. V.

Geological Quarterly

|

2005

|

Vol. 49, No. 2

185-194

EN

Oxygen and carbon stable isotope records of two stalagmites from NW Romania provide a continuous climatic record between 14.8 and 5.6 ka BP. The chronology is established by 21 TIMS uranium series ages. Uncertain ties in the isotope chronology range between ±20 and ±100 yr. The δ18 O values are positively correlated with temperature, whereas δ13 C fluctuations suggest changes in soil CO2 production. Lateglacial deposition of both stalagmites started at ~14.8 ka BP. The delta 18 O records subsequently show a slow decline in temperatures until 12.6 ka BP. Three warmer periods with increased soil productivity occurred at 14.5-13.9 ka BP, 13.6-13.2 ka BP, and 12.9-12.6 ka BP. Lower delta 18 O and high δ13 C values between 12.6 and 11.4 (11.7) ka BP in dicate a cold and dry climate during the Younger Dryas (GS-1). During the Early Holocene, three short cold intervals are marked on the δ 18 O profiles at 11.0-10.6, 10.5-10.2 and 9.4-9.1 ka BP. For the remainder of the Holocene sequence, the δ18 O records show less variation between 9 and 7.8 ka BP and gradual warming from 7.6-5.6 ka BP. The speleothem records correlate with the Green land ice core records and with other proxies through out Europe and the North Atlantic region.

3

Palaeohydrological aspect of transformation of lakes into peat bogs during middle holocene on the basis of cladocera analysis in the northern Poland

Szeroczyńska K., Gąsiorowski M.

Studia Quaternaria

|

2002

|

Vol. 19

55--60

EN

Cladocera are a group of water animals, which are strongly dependent on environmental conditions. The ratio of planktonic to littoral Cladocera species is a widely used tool in palaeohydrological reconstruction of lakes' water level changes. Interpretation of this ratio is still unclear and requires further evidence. The simplest indicator of water level, which can be used in tracing lake-peat bog transitions, is the presence or absence of Cladocera and the character of its disappearance. In general, two models of Cladocera decline are observed. The first model is characterized by a very abrupt disappearance of all species, whereas the second one, with an intermediate stage, is characterized by domination of specific species. These two models are related to different types of terminal history of the water body. Even after a total disappearance of water in the peat bogs, there were episodes of some pioneer cladoceran species presence, correlated with periods of humid climate.