Bat guano and historical evidence of climate changes in the west of Iran during the Late Holocene (Meghalayan Stage)

This study investigated the influence of sea-level and climate changes on the decreased fluvial aggradation and subsequent widespread peat initiation in the middle to late-Holocene in the Ishikari lowland, which is a coastal floodplain formed in response to the postglacial sea-level change. By introducing a new approach to separately evaluate the rates of organic and clastic sediment input, we demonstrated that the peat began to form when the fluvial sedimentation rate was significantly decreased (less than 0.6 mm/yr), while plant macrofossil analysis suggested that lowering of water level is also important to the peat initiation. Such changes in sedimentary environment may be associated with the abrupt abandonment of crevasse splays. The concentrated ages of the peat initiation around 5600–5000, 4600–4300, and 4100–3600 cal. BP suggest that an allogenic control promoted the abandonment of crevasse splays, and different onset ages can be explained by different fluvial responses of the Ishikari River and its tributaries. The abandonment of crevasse splays could result from sea-level fall or decreased precipitation. While submillennial sea-level fluctuations coincident with the peat initiation have not been reported in coastal lowlands of Japan, the close comparison of the onset ages and decreased precipitation recorded in a stalagmite from China, which represents the strength of the East Asian summer monsoon (EASM), suggests that decrease in precipitation led to the abandonment of crevasse splays. Our results may indicate that similar fluvial responses might be common in other coastal floodplains affected by the EASM.

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Detailed reconstruction of the functional state of the Central Yamal khasyrey as a response to local conditions and regional climate changes in the late Holocene

IOP Conference Series Earth and Environmental Science ◽

10.1088/1755-1315/48/1/012010 ◽

2016 ◽

Vol 48 ◽

pp. 012010

Author(s):

Yu I Preis ◽

G V Simonova ◽

E A Slagoda

Keyword(s):

Functional State ◽

Late Holocene ◽

Climate Changes ◽

Regional Climate ◽

Local Conditions

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A Late Holocene Paleoecological Record from Torrey Pines State Reserve, California

Quaternary Research ◽

10.1006/qres.1999.2121 ◽

2000 ◽

Vol 53 (3) ◽

pp. 341-351 ◽

Cited By ~ 16

Author(s):

Kenneth L. Cole ◽

Eugene Wahl

Keyword(s):

Late Holocene ◽

Climate Changes ◽

Regional Climate ◽

Sediment Chemistry ◽

Fossil Pollen ◽

Plant Type ◽

The North ◽

Low Genetic Diversity ◽

Core Site ◽

Pollen And Spores

AbstractPaleoenvironments of the Torrey Pines State Reserve were reconstructed from a 3600-yr core from Los Peñasquitos Lagoon using fossil pollen, spores, charcoal, chemical stratigraphy, particle size, and magnetic susceptibility. Late Holocene sediments were radiocarbon dated, while the historical sediments were dated using sediment chemistry, fossil pollen, and historical records. At 3600 yr B.P., the estuary was a brackish-water lagoon. By 2800 yr B.P., Poaceae (grass) pollen increased to high levels, suggesting that the rising level of the core site led to its colonization by Spartina foliosa (cord-grass), the lowest-elevation plant type within regional estuaries. An increase in pollen and spores of moisture-dependent species suggests a climate with more available moisture after 2600 yr B.P. This change is similar to that found 280 km to the north at 3250 yr B.P., implying that regional climate changes were time-transgressive from north to south. Increased postsettlement sediment input resulted from nineteenth-century land disturbances caused by grazing and fire. Sedimentation rates increased further in the twentieth century due to closure of the estuarine mouth. The endemic Pinus torreyana (Torrey pine) was present at the site throughout this 3600-yr interval but was less numerous prior to 2100 yr B.P. This history may have contributed to the low genetic diversity of this species.

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Charcoal signatures defined by multivariate analysis of charcoal records from 10 lakes in northwest Wisconsin (USA)

Quaternary Research ◽

10.1016/j.yqres.2010.08.007 ◽

2011 ◽

Vol 75 (1) ◽

pp. 125-137 ◽

Cited By ~ 7

Author(s):

Elizabeth A. Lynch ◽

Sara C. Hotchkiss ◽

Randy Calcote

Keyword(s):

Late Holocene ◽

Climate Changes ◽

Regional Climate ◽

Fire Regimes ◽

Small Scale ◽

Regional Patterns ◽

Crown Fires ◽

Sand Plain ◽

In Fire ◽

Standard Techniques

AbstractWe show how sedimentary charcoal records from multiple sites within a single landscape can be used to compare fire histories and reveal small scale patterns in fire regimes. Our objective is to develop strategies for classifying and comparing late-Holocene charcoal records in Midwestern oak- and pine-dominated sand plain ecosystems where fire regimes include a mix of surface and crown fires. Using standard techniques for the analysis of charcoal from lake sediments, we compiled 1000- to 4000-yr-long records of charcoal accumulation and charcoal peak frequencies from 10 small lakes across a sand plain in northwestern Wisconsin. We used cluster analysis to identify six types of charcoal signatures that differ in their charcoal influx rates, amount of grass charcoal, and frequency and magnitude of charcoal peaks. The charcoal records demonstrate that while fire histories vary among sites, there are regional patterns in the occurrence of charcoal signature types that are consistent with expected differences in fire regimes based on regional climate and vegetation reconstructions. The fire histories also show periods of regional change in charcoal signatures occurring during times of regional climate changes at ~700, 1000, and 3500 cal yr BP.

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Quaternary glaciations in the Verkhoyansk Mountains, Northeast Siberia

Quaternary Research ◽

10.1016/j.yqres.2010.04.003 ◽

2010 ◽

Vol 74 (1) ◽

pp. 145-155 ◽

Cited By ~ 24

Author(s):

Georg Stauch ◽

Frank Lehmkuhl

Keyword(s):

Climate Changes ◽

Ice Sheets ◽

Optically Stimulated Luminescence ◽

Ural Mountains ◽

The West ◽

Local Climate ◽

Terminal Moraine ◽

Geomorphological Mapping ◽

Eurasian Continent ◽

Polar Ural

AbstractGeomorphological mapping revealed five terminal moraines in the central Verkhoyansk Mountains. The youngest terminal moraine (I) was formed at least 50 ka ago according to new IRSL (infrared optically stimulated luminescence) dates. Older terminal moraines in the western foreland of the mountains are much more extensive in size. Although the smallest of these older moraines, moraine II, has not been dated, moraine III is 80 to 90 ka, moraine IV is 100 to 120 ka, and the outermost moraine V was deposited around 135 ka. This glaciation history is comparable to that of the Barents and Kara ice sheet and partly to that of the Polar Ural Mountains regarding the timing of the glaciations. However, no glaciation occurred during the global last glacial maximum (MIS 2). Based on cirque orientation and different glacier extent on the eastern and western flanks of the Verkhoyansk Mountains, local glaciations are mainly controlled by moisture transport from the west across the Eurasian continent. Thus glaciations in the Verkhoyansk Mountains not only express local climate changes but also are strongly influenced by the extent of the Eurasian ice sheets.

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The Amazons of Dahomey

Oxford Research Encyclopedia of African History ◽

10.1093/acrefore/9780190277734.013.274 ◽

2020 ◽

Author(s):

Agbenyega Adedze

Keyword(s):

Oral Tradition ◽

West African ◽

Oral Traditions ◽

Historical Evidence ◽

The West ◽

West African Coast ◽

African Coast ◽

History Of ◽

French Colonial ◽

Female Fighters

The Amazons in general come from Greek legend and myth without any palpable historical evidence. However, there is no doubt about the historical female fighters of the erstwhile Kingdom of Dahomey (Danhome or Danxome) in West Africa, which survived until their defeat by the French colonial forces in 1893. The history of the historical Amazons of the Kingdom of Dahomey stems from vast amounts of oral tradition collected and analyzed over the years, as well as written accounts by Europeans who happened to have visited the kingdom or lived on the West African coast since Dahomey’s foundation in the 17th century to its demise in the late 19th century. These sources have been reviewed and debated by several scholars (including Amélie Degbelo, Stanley B. Alpern, Melville J. Herskovits, Hélène d’Almeida-Topor, Boniface Obichere, Edna G. Bay, Robin Law, Susan Preston Blier, Auguste Le Herisse, etc.), who may or may not agree on the narrative of the founding of the kingdom or the genesis of female fighters in the Dahomean army. Nonetheless, all scholars agree that the female forces traditionally called Ahosi/Mino did exist and fought valiantly in many of Dahomey’s battles against their neighbors (Oyo, Ouemenou, Ouidah, etc.) and France. The history of the Ahosi/Mino is intricately linked to the origins and political and social development of the Kingdom of Dahomey. Ahosi/Mino are still celebrated in the oral traditions of the Fon.

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Late Holocene plant and climate evolution at Lake Yoa, northern Chad: pollen data and climate simulations

Climate of the Past ◽

10.5194/cp-7-1351-2011 ◽

2011 ◽

Vol 7 (4) ◽

pp. 1351-1362 ◽

Cited By ~ 32

Author(s):

A.-M. Lézine ◽

W. Zheng ◽

P. Braconnot ◽

G. Krinner

Keyword(s):

Late Holocene ◽

Climate Changes ◽

Direct Consequence ◽

Atmospheric Model ◽

Plant Distribution ◽

Time Interval ◽

Pollen Data ◽

Tropical Plant ◽

Climate Simulations ◽

Dry Spell

Abstract. The discovery of groundwater-fed Lake Yoa (19.03° N, 20.31° E) in the hyperarid desert of northern Chad by the German research team ACACIA headed by S. Kröpelin provides a unique, continuous sedimentary sequence of late Holocene age available in the entire Saharan desert. Here we present pollen data and climate simulations using the LMDZ atmospheric model with a module representing the climatologically-relevant thermal and hydrological processes occurring above and beneath inland water surfaces to document past environmental and climate changes during the last 6000 cal yr BP. Special attention is paid to wind strength and direction, length and amplitude of the rainy season, and dry spell occurrence, all of which are of primary importance for plant distribution and pollen transport. In addition to climate changes and their impact on the natural environment, anthropogenic changes are also discussed. Two main features can be highlighted: (1) the shift from an earlier predominantly monsoonal climate regime to one dominated by northern Mediterranean fluxes that occurred after 4000 cal yr BP. The direct consequence of this was the establishment of the modern desert environment at Yoa at 2700 cal yr BP. (2) Changes in climate parameters (simulated rainfall amount and dry spell length) between 6 and 4000 cal yr BP were comparatively minor. However, changes in the seasonal distribution of precipitation during this time interval dramatically affected the vegetation composition and were at the origin of the retreat of tropical plant communities from Lake Yoa.

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Spatiotemporal Variation in ΔR on the West Coast of North America in the Late Holocene: Implications for Dating the Shells of Marine Mollusks

American Antiquity ◽

10.1017/aaq.2020.47 ◽

2020 ◽

Vol 85 (4) ◽

pp. 676-693

Author(s):

Ian Hutchinson

Keyword(s):

North America ◽

West Coast ◽

Late Holocene ◽

Southern Oscillation ◽

Tidal Energy ◽

Spatiotemporal Resolution ◽

The West ◽

Summer Maximum ◽

High Alkalinity ◽

High Degree

Radiocarbon ages on mollusk shells, which account for about half of the more than 8,000 dates from cultural deposits on the west coast of North America, need to be corrected for the local marine reservoir effect (ΔR) to yield true ages. Assays on “prebomb” shells show that ΔR increases poleward, echoing the age gradient in offshore waters. The meridional gradient in ΔR is not appreciably affected by the transition either from an upwelling regime to a downwelling regime north of 40°N–45°N or from a winter maximum-high alkalinity river discharge pattern to a summer maximum-low alkalinity pattern at the same latitude, probably because these changes are offset by increasing storminess and tidal energy in coastal areas. Mesoscale variations in ΔR along this gradient are attributable to contrasts in shore morphology and exposure. Data from 123 shell-wood pairs reveal similar patterns of temporal variation in ΔR in the late Holocene in the coastal ecoregions. The characteristic temporal pattern echoes phases of variable El Niño-Southern Oscillation (ENSO) activity. The high degree of variability in ΔR argues against the indiscriminate application of regionally uniform or trans-Holocene ΔR values and demands improvements in spatiotemporal resolution if shell is used to date cultural deposits.

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