Late Quaternary Arthropod Remains from Sonoran Desert Packrat Middens, Southwestern Arizona and Northwestern Sonora

1988 ◽  
Vol 29 (3) ◽  
pp. 277-293 ◽  
Author(s):  
W. Eugene Hall ◽  
Thomas R. Van Devender ◽  
Carl A. Olson
Keyword(s):  
Sonoran Desert ◽  
Colorado River ◽  
Late Quaternary ◽  
Taxonomic Resolution ◽  
Radiocarbon Dates ◽  
Temperature And Precipitation ◽  
Arthropod Fauna ◽  
Juniper Woodland ◽  
Insufficient Knowledge ◽  
The Last Glacial

A total of 50 arthropod taxa were identified from 41 fossil packrat (Neotoma sp.) middens from 160 to 625 m elevation in three study areas in the Lower Colorado River Valley subdivision of the Sonoran Desert. Radiocarbon dates associated with the middens range from >43,200 to 610 yr B.P. The fauna in the Tinajas Altas Mountains, southwestern Arizona, was relatively modern by ca. 10,000 yr B.P. in the early Holocene although a California juniper woodland persisted in the area until 8970 yr B.P. In contrast the fauna of the Hornaday Mountains, northwestern Sonora, increased dramatically in species richness after 4000 yr B.P. Although we are limited by poor taxonomic resolution and by insufficient knowledge of current distributions, the arthropod fauna may have been much more conservative than the regional flora during the last glacial/interglacial climatic cycle. Decreasing differences between modern and glacial climates (both temperature and precipitation) at lower latitudes and elevations may have resulted in minimal changes in the arthropod fauna of the Sonoran Desert lowlands.

Tephra anchored floating varve chronology covering ca. 19.0-11.0 ka BP in new core from Lake Lago Grande di Monticchio: preliminary results

2020 ◽  
Author(s):  
Xueru Zhao ◽  
Sabine Wulf ◽  
Markus J. Schwab ◽  
Rik Tjallingii ◽  
Achim Brauer
Keyword(s):  
High Resolution ◽  
Environmental Changes ◽  
Late Quaternary ◽  
Methodological Approach ◽  
Radiocarbon Dates ◽  
Thin Sections ◽  
Last Glacial ◽  
Varve Chronology ◽  
Varve Counting ◽  
The Last Glacial

<p>The high-resolution Monticchio (MON) sediment record has been demonstrated to be a key archive for reconstructing climate and environmental changes in the central Mediterranean for the last glacial-interglacial cycle. New sediment cores have been retrieved in April 2016 to investigate particularly the transition from the Last Glacial Maximum into the Holocene with a new high-resolution methodological approach. A floating varve chronology spanning ca. 8,000 years has been established by varve counting on thin sections using a petrographic microscope and layer thickness based sedimentation rate estimates for non- or poorly varved intervals. Varve counting is based on detailed seasonal deposition models of five different varve types. The resulting floating chronology consist of 66.6% individually counted varves and 33.4% interpolated years. The uncertainty estimate of the floating chronology has been determined by double counting and amounts to ±5.8%.</p><p>The floating chronology is anchored to an absolute chronology using the Agnano Pomici Principali tephra, dated at 11,999±52 cal yrs BP from paleosols overlying proximal tephra (Bronk Ramsey et al. 2015), is a suitable anchoring point to cross correlation. The resulting varve-based chronology has been compared with several other marker tephras dated elsewhere including the Soccavo 4 tephra (11,700±150 cal yrs BP), the Neapolitan Yellow Tuff (NYT; 14,194±172 cal yrs BP) and the Greenish tephra (19226±104 cal yrs BP). Further comparison with published (Hajdas et al. 1997) and new radiocarbon dates from different terrestrial macro remains are discussed in this paper. This study presents an independent chronology for the last glacial/interglacial transition for a comparison of MON data with high-resolution lake records western and central Europe.</p><p>References</p><p>Bronk Ramsey, C., P. G. Albert, S. P. E. Blockley, M. Hardiman, R. A. Housley, C. S. Lane, S. Lee, I. P. Matthews, V. C. Smith & J. J. Lowe (2015) Improved age estimates for key Late Quaternary European tephra horizons in the RESET lattice. Quaternary Science Reviews, 118<strong>,</strong> 18-32.</p><p>Hajdas, I., G. Bonani, B. Zolitschka, A. Brauer & J. Negendank (1997) 14C Ages of Terrestrial Macrofossils from Lago Grande Di Monticchio (Italy). Radiocarbon, 40<strong>,</strong> 803-807.</p>

scholarly journals Underwater faunal assemblages: radiocarbon dates and late Quaternary vertebrates from Cold Lake, Alberta and Saskatchewan, Canada

2018 ◽  
Vol 55 (3) ◽  
pp. 283-294
Author(s):  
Christopher N. Jass ◽  
Devyn Caldwell ◽  
Christina I. Barrón-Ortiz ◽  
Alwynne B. Beaudoin ◽  
Jack Brink ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Faunal Remains ◽  
Radiocarbon Dates ◽  
East Central ◽  
Faunal Assemblages ◽  
History Of ◽  
Cold Lake ◽  
The Last Glacial Maximum ◽  
Insight Into ◽  
The Last Glacial

Late Quaternary faunal remains from three underwater settings in Cold Lake, Alberta and Saskatchewan, Canada, include at least 13 vertebrate taxa consistent with assemblages that postdate the Last Glacial Maximum (LGM). Seven new radiocarbon dates range from 10 350 ± 40 to 161 ± 23 years BP and provide insight into the post-LGM biotic history of east-central Alberta and west-central Saskatchewan. The presence of an essentially modern large mammal biota is suggested for the mid-Holocene, and possibly earlier, if the absence of extinct or extirpated taxa in association with Late Pleistocene Bison at the Alberta–Saskatchewan site is meaningful. Taphonomically, some of the remains suggest deposition in open environments during the Holocene, possibly when lake levels were lower. The recovery of late Quaternary faunal remains from a present-day lacustrine setting is novel, and suggests that similar records may occur in other lakes in western Canada, including those in areas with scarce Quaternary vertebrate records.

Stable isotope and 14C study of biogenic calcrete in a termite mound, Western Cape, South Africa, and its palaeoenvironmental significance

2009 ◽  
Vol 72 (2) ◽  
pp. 258-264 ◽  
Author(s):  
Alastair J. Potts ◽  
Jeremy J. Midgley ◽  
Chris Harris
Keyword(s):  
South Africa ◽  
Arid Zone ◽  
Late Quaternary ◽  
Western Cape ◽  
Cam Plants ◽  
Termite Mounds ◽  
Last Glacial Period ◽  
Radiocarbon Dates ◽  
Progressive Decline ◽  
The Last Glacial

AbstractLate Quaternary terrestrial climate records from the semi-arid zone of the Western Cape of South Africa are rare. However, palaeoenvironmental information may be inferred from ancient termite mounds of the region. Calcrete lenses in these mounds have δ13C and δ18O values that show systematic changes with radiocarbon dates, which range from 33,629–36,709 to 21,676–23,256 cal yr BP. These dates confirm that these heuweltjies had been present in the landscape since the last glacial period. The decrease in δ13C and δ18O from 33,629–36,709 to 21,676–23,256 cal yr BP indicates that climate information is recorded by the calcretes. It is suggested that a progressive decline in air temperature and an increase in moisture availability, and a decline in abundance of C4 or CAM plants, occurred in the region during the time heuweltjie calcite precipitated.

Mid- to Late-Wisconsin Pollen Record of San Felipe Basin, Baja California

2002 ◽  
Vol 58 (1) ◽  
pp. 84-92 ◽  
Author(s):  
Marı́a Socorro Lozano-Garcı́a ◽  
Beatriz Ortega-Guerrero ◽  
Susana Sosa-Nájera
Keyword(s):  
Sonoran Desert ◽  
Baja California ◽  
First Record ◽  
Pollen Record ◽  
Radiocarbon Dates ◽  
Pollen Types ◽  
Dry Conditions ◽  
Intermediate Part ◽  
Significant Increment ◽  
The Last Glacial

AbstractA lacustrine sequence from Laguna Seca San Felipe, Baja California, in the southwestern Sonoran Desert, provides the first record of mid- to late-Wisconsin vegetation in one of the driest regions of North America. Pollen analysis was performed in the intermediate part of the sequence from ca. 44,000 to ca. 13,000 14C yr B.P. according to six 14C radiocarbon dates. Sedimentation of eolian sands prior to 44,000 14C yr B.P. indicates dry conditions. High pollen concentration of montane and chaparral species in the pollen assemblages contrast with the modern desert vegetation. Sixty-four pollen types were identified. The source of mid- to late-Wisconsin sedimentation must have been the plant communities in the surrounding highlands of the basin. Mid-Wisconsin pollen assemblages dominated by pines, junipers, and Artemisia reflect humid conditions in the area. By late Wisconsin time, a significant increment in junipers indicates a lowering in the altitudinal ranges of woodlands/chaparral. Pollen from wind-pollinated species is abundant while desert plants, specifically animal or insect pollinated species, are poorly represented. The San Felipe record does not identify the Last Glacial Maximum as the time of greatest effective moisture, as suggested by pluvial lake levels and other paleoclimatic evidence in the soutwestern United States.

Absence of Last Glacial Maximum Records in Lowland Tropical Forests

1998 ◽  
Vol 49 (2) ◽  
pp. 233-237 ◽  
Author(s):  
Marie-Pierre Ledru ◽  
Jacques Bertaux ◽  
Abdelfettah Sifeddine ◽  
Kenitiro Suguio
Keyword(s):  
South America ◽  
Tropical Forests ◽  
Last Glacial Maximum ◽  
Sedimentation Rate ◽  
Glacial Maximum ◽  
Radiocarbon Dates ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
Pollen Records ◽  
The Last Glacial

Environmental conditions of the lowland tropical forests during the last glacial maximum (LGM) between ca 20,000 and 18,000 14C yr B.P., are reevaluated in terms of dating control and lithology analyzed in seven pollen records from South America. The reevaluation shows that probably in none of the published records are LGM sediments present or abundant. This conclusion is based on the occurrence of abrupt lithologic changes coupled with changes in sedimentation rate interpolated from radiocarbon dates. These findings suggest that the LGM was represented probably by a hiatus of several thousand years, indicative of drier climates than before or after.

Late Quaternary Paleotemperatures Derived from a Speleothem from Cango Caves, Cape Province, South Africa

1992 ◽  
Vol 37 (2) ◽  
pp. 203-213 ◽  
Author(s):  
A.S. Talma ◽  
John C. Vogel
Keyword(s):  
South Africa ◽  
Isotopic Composition ◽  
Late Quaternary ◽  
Carbon Isotopic Composition ◽  
Temperature Record ◽  
The Past ◽  
Carbon Isotopic ◽  
Groundwater Aquifer ◽  
Combining Data ◽  
The Last Glacial

AbstractAn oxygen isotope temperature record over a large part of the past 30,000 yr has been obtained for the southern Cape Province of South Africa by combining data on the isotopic composition of a stalagmite from a deep cave with that of a confined groundwater aquifer in the same region. Results show that temperatures during the last glacial maximum were on average about 6°C lower than those today, with peaks up to 7°C lower. A detailed analysis of the past 5000 yr suggests multiple fluctuations, with generally lower temperatures (1–2°C) around 4500 and 3000 yr B.P. The carbon isotopic composition of the stalagmite indicates significant vegetation changes between the late Pleistocene and today, and also during the second half of the Holocene.

scholarly journals Sea level implications from Late Quaternary/Holocene paleosols from the Oujiang Delta, China

Radiocarbon ◽  
2018 ◽  
Vol 61 (1) ◽  
pp. 83-99
Author(s):  
Daidu Fan ◽  
Shuai Shang ◽  
George Burr
Keyword(s):  
Sea Level ◽  
East China Sea ◽  
Late Quaternary ◽  
Sediment Cores ◽  
East China ◽  
The East China Sea ◽  
China Sea ◽  
Mis 3 ◽  
Plant Matter ◽  
The Last Glacial

ABSTRACTWe describe two coastal paleosols recovered in sediment cores from the Oujiang Delta, Southeast China. These provide useful benchmarks for past sea level change on the East China Sea coast. Radiocarbon (14C) dates on charcoal and plant matter show that one formed during Marine Isotope Stage 3 (MIS 3) and was exposed for perhaps 20 ka, during the Last Glacial Maximum. The other formed in the Early Holocene and was briefly exposed, during a period of fluctuating sea level. Similar paleosols have been described from the Changjiang (Yangtze) Delta, and at many other sites from the East China Sea. The MIS 3 paleosol records a regional relative sea level of about –27 m at the end of MIS 3. While this value is consistent with other paleo sea level estimates for the East China Sea region, it is much higher than predicted by eustatic sea level estimates.

scholarly journals Interactions between Climate Change and Complex Topography Drive Observed Streamflow Changes in the Colorado River Basin

2018 ◽  
Vol 19 (10) ◽  
pp. 1637-1650 ◽  
Author(s):  
Kurt C. Solander ◽  
Katrina E. Bennett ◽  
Sean W. Fleming ◽  
David S. Gutzler ◽  
Emily M. Hopkins ◽  
...  
Keyword(s):  
Climate Change ◽  
United States ◽  
River Basin ◽  
Colorado River ◽  
Food Resource ◽  
The United States ◽  
Colorado River Basin ◽  
Temperature And Precipitation ◽  
Strong Relation ◽  
High Elevations

Abstract The Colorado River basin (CRB) is one of the most important watersheds for energy, water, and food security in the United States. CRB water supports 15% of U.S. food production, more than 50 GW of electricity capacity, and one of the fastest growing populations in the United States. Energy–water–food nexus impacts from climate change are projected to increase in the CRB. These include a higher incidence of extreme events, widespread snow-to-rain regime shifts, and a higher frequency and magnitude of climate-driven disturbances. Here, we empirically show how the historical annual streamflow maximum and hydrograph centroid timing relate to temperature, precipitation, and snow. In addition, we show how these hydroclimatic relationships vary with elevation and how the elevation dependence has changed over this historical observational record. We find temperature and precipitation have a relatively weak relation (|r| < 0.3) to interannual variations in streamflow timing and extremes at low elevations (<1500 m), but a relatively strong relation (|r| > 0.5) at high elevations (>2300 m) where more snow occurs in the CRB. The threshold elevation where this relationship is strongest (|r| > 0.5) is moving uphill at a rate of up to 4.8 m yr−1 (p = 0.11) and 6.1 m yr−1 (p = 0.01) for temperature and precipitation, respectively. Based on these findings, we hypothesize where warming and precipitation-related streamflow changes are likely to be most severe using a watershed-scale vulnerability map to prioritize areas for further research and to inform energy, water, and food resource management in the CRB.

scholarly journals Statistical downscaling of a climate simulation of the last glacial cycle: temperature and precipitation over Northern Europe

2014 ◽  
Vol 10 (4) ◽  
pp. 1489-1500 ◽  
Author(s):  
N. Korhonen ◽  
A. Venäläinen ◽  
H. Seppä ◽  
H. Järvinen
Keyword(s):  
Large Scale ◽  
Climate Model ◽  
Ice Sheet ◽  
Additive Models ◽  
Northern Europe ◽  
Glacial Cycle ◽  
Explanatory Variables ◽  
Last Glacial ◽  
Temperature And Precipitation ◽  
The Last Glacial

Abstract. Earth system models of intermediate complexity (EMICs) have proven to be able to simulate the large-scale features of glacial–interglacial climate evolution. For many climatic applications the spatial resolution of the EMICs' output is, however, too coarse, and downscaling methods are needed. In this study we introduce a way to use generalized additive models (GAMs) for downscaling the large-scale output of an EMIC in very different climatological conditions ranging from glacial periods to current relatively warm climates. GAMs are regression models in which a combination of explanatory variables is related to the response through a sum of spline functions. We calibrated the GAMs using observations of the recent past climate and the results of short time-slice simulations of glacial climate performed by the relatively high-resolution general circulation model CCSM (Community Climate System Model) and the regional climate model RCA3 (Rossby Centre regional Atmospheric climate model). As explanatory variables we used the output of a simulation by the CLIMBER-2 (CLIMate and BiosphERe model 2) EMIC of the last glacial cycle, coupled with the SICOPOLIS (SImulation COde for POLythermal Ice Sheets) ice sheet model, i.e. the large-scale temperature and precipitation data of CLIMBER-2, and the elevation, distance to ice sheet, slope direction and slope angle from SICOPOLIS. The fitted GAMs were able to explain more than 96% of the temperature response with a correlation of >0.98 and more than 59% of the precipitation response with a correlation of >0.72. The first comparison with two pollen-based reconstructions of temperature for Northern Europe showed that CLIMBER-2 data downscaled by GAMs corresponded better with the reconstructions than did the bilinearly interpolated CLIMBER-2 surface temperature.

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