Late Pleistocene glacial geomorphology and environment of the Hand Hills region and southern Alberta, related to Middle Wisconsin fossil prairie dog sites

1999 ◽  
Vol 36 (9) ◽  
pp. 1567-1581 ◽  
Author(s):  
R R Young ◽  
J A Burns ◽  
R B Rains ◽  
D B Schowalter
Keyword(s):  
Late Pleistocene ◽  
Ice Sheets ◽  
High Elevation ◽  
Prairie Dogs ◽  
Bone Collagen ◽  
Prairie Dog ◽  
Radiocarbon Dates ◽  
Glacial Sediments ◽  
South Central ◽  
Glacial Environments

Ichnofossils (burrow casts) and fossils from an extinct form of prairie dog, Cynomys niobrarius churcherii, in the Hand Hills of south-central Alberta, have provided an important Late Pleistocene stratigraphic marker. The marker fossils provide relative and chronostratigraphic (radiocarbon) ages for nonglacial, periglacial, glacial, and glaciotectonic events and environments in the region. The high-elevation, hilltop position of the fossil sites (~200 m above the surrounding plains) permits reliable extrapolations of glacial environments to the surrounding region. The burrow casts were preserved by infilling from surrounding and overlying sediments through processes of inwashing and animal activity. Three thousand bones, primarily of the extinct prairie dog Cynomys niobrarius churcherii, were recovered from one site, and several hundred more from other locations. Accelerator radiocarbon dates (AMS) on bone collagen show that the prairie dogs lived in the area from at least 33 000 BP to around 22 000 BP. Prairie dog burrow casts crosscut well-developed periglacial structures and stratigraphically underlie all glacial sediments, indicating that harsh periglacial environments preceded their colonization and that the region was later submerged by Laurentide ice. Deformed sediments, 0.5 to 1.5 m thick, were found throughout the upland. The products of deformation overlie, truncate, and (or) incorporate burrow casts, indicating that only limited erosion and glacial deformation occurred during glaciation. Reconstructed ice sheet profiles show a northwest-southeast flow that could only have been achieved by coalescent Laurentide and Cordilleran ice sheets. This demonstrates that a theoretical "ice-free corridor" that some think persisted between the ice sheets during the Late Wisconsin "maximum," did not exist.

New excavations at the late Pleistocene site of Chinchihuapi I, Chile

2019 ◽  
Vol 92 (1) ◽  
pp. 70-80 ◽  
Author(s):  
Tom D. Dillehay ◽  
Carlos Ocampo ◽  
Jose Saavedra ◽  
Mario Pino ◽  
Linda Scott-Cummings ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Early Holocene ◽  
Occupied Site ◽  
Radiocarbon Dates ◽  
Central Chile ◽  
South Central ◽  
Cool Temperate ◽  
Human Use ◽  
Monte Verde ◽  
Point Type

AbstractThis paper presents new excavation data on the Chinchihuapi I (CH-I) locality within the Monte Verde site complex, located along Chinchihuapi Creek in the cool, temperate Valdivian rain forest of south-central Chile. The 2017 and 2018 archaeological excavations carried out in this open-air locality reveal further that CH-I is an intermittently occupied site dating from the Early Holocene (~10,000 cal yr BP) to the late Pleistocene (at least ~14,500 cal yr BP) and probably earlier. A new series of radiocarbon dates refines the chronology of human use of the site during this period. In this paper, we describe the archaeological and stratigraphic contexts of the recent excavations and analyze the recovered artifact assemblages. A fragmented Monte Verde II point type on an exotic quartz newly recovered from excavations at CH-I indicates that this biface design existed in at least two areas of the wider site complex ~14,500 cal yr BP. In addition, associated with the early Holocene component at CH-I are later Paijan-like points recovered with lithic tools and debris and other materials. We discuss the geographic distribution of diagnostic artifacts from the site and their probable relationship to other early sites in South America.

scholarly journals Yedoma Ice Complex of the Buor Khaya Peninsula (southern Laptev Sea)

2017 ◽  
Vol 14 (5) ◽  
pp. 1261-1283 ◽  
Author(s):  
Lutz Schirrmeister ◽  
Georg Schwamborn ◽  
Pier Paul Overduin ◽  
Jens Strauss ◽  
Margret C. Fuchs ◽  
...  
Keyword(s):  
Organic Matter ◽  
Late Pleistocene ◽  
Thermal State ◽  
Distribution Data ◽  
Laptev Sea ◽  
Western Coast ◽  
Radiocarbon Dates ◽  
South Central ◽  
Marine Realm ◽  
Ice Complex

Abstract. The composition of perennially frozen deposits holds information on the palaeo-environment during and following deposition. In this study, we investigate late Pleistocene permafrost at the western coast of the Buor Khaya Peninsula in the south-central Laptev Sea (Siberia), namely the prominent eastern Siberian Yedoma Ice Complex (IC). Two Yedoma IC exposures and one drill core were studied for cryolithological (i.e. ice and sediment features), geochemical, and geochronological parameters. Borehole temperatures were measured for 3 years to capture the current thermal state of permafrost. The studied sequences were composed of ice-oversaturated silts and fine-grained sands with considerable amounts of organic matter (0.2 to 24 wt %). Syngenetic ice wedges intersect the frozen deposits. The deposition of the Yedoma IC, as revealed by radiocarbon dates of sedimentary organic matter, took place between 54.1 and 30.1 kyr BP. Continued Yedoma IC deposition until about 14.7 kyr BP is shown by dates from organic matter preserved in ice-wedge ice. For the lowermost and oldest Yedoma IC part, infrared-stimulated luminescence dates on feldspar show deposition ages between 51.1 ± 4.9 and 44.2 ± 3.6 kyr BP. End-member modelling was applied to grain-size-distribution data to determined sedimentation processes during Yedoma IC formation. Three to five robust end-members were detected within Yedoma IC deposits, which we interpret as different modes of primary and reworked unconfined alluvial slope and fan deposition as well as of localized eolian and fluvial sediment, which is overprinted by in situ frost weathering. The cryolithological inventory of the Yedoma IC preserved on the Buor Khaya Peninsula is closely related to the results of other IC studies, for example, to the west on the Bykovsky Peninsula, where formation time (mainly during the late Pleistocene marine isotope stages (MIS) 3 interstadial) and formation conditions were similar. Local freezing conditions on Buor Khaya, however, differed and created solute-enriched (salty) and isotopically light pore water pointing to a small talik layer and thaw-bulb freezing after deposition. Due to intense coastal erosion, the biogeochemical signature of the studied Yedoma IC represents the terrestrial end-member, and is closely related to organic matter currently being deposited in the marine realm of the Laptev Sea shelf.

Effects of habitat quality on growth, age of first reproduction, and dispersal in Gunnison's prairie dogs (Cynomys gunnisoni)

1985 ◽  
Vol 63 (12) ◽  
pp. 2835-2840 ◽  
Author(s):  
Linda S. Rayor
Keyword(s):  
Sexual Maturity ◽  
Growing Season ◽  
Ground Squirrels ◽  
Prairie Dogs ◽  
Prairie Dog ◽  
Adult Weight ◽  
Cynomys Gunnisoni ◽  
South Central ◽  
Younger Age ◽  
Gunnison's Prairie Dogs

Populations of the highly social Gunnison's prairie dog (Cynomys gunnisoni) were studied at two sites in south central Colorado. The sites differed in availability of water, duration of the growing season, and the diversity and quantity of edible vegetation. At the lusher site, Quartz Creek, all age- and sex classes weighed significantly more than their counterparts at the more barren site, Blue Mesa. Growth rates and overwinter survival of Quartz Creek young were higher than at Blue Mesa. Two of 5 yearling females raised litters at Quartz Creek, whereas none of 15 yearling females weaned litters at Blue Mesa. Quartz Creek females produced larger litters [Formula: see text] than Blue Mesa females [Formula: see text]. At Quartz Creek, 6 of 17 yearlings dispersed from their natal harem, but none of the 31 yearlings at Blue Mesa dispersed. Thus, in a favorable habitat, Gunnison's prairie dogs were heavier, reached sexual maturity more rapidly, and dispersed at a younger age than in a less favorable habitat. These results provide intraspecific support for Armitage's hypothesis that delayed sexual maturity and dispersal in the large-bodied, social ground squirrels is associated with the age at which immatures attain adult weight.

scholarly journals Yedoma Ice Complex of the Buor Khaya Peninsula (southern Laptev Sea)

2016 ◽  
Author(s):  
Lutz Schirrmeister ◽  
Georg Schwamborn ◽  
Pier Paul Overduin ◽  
Jens Strauss ◽  
Margret C. Fuchs ◽  
...  
Keyword(s):  
Organic Matter ◽  
Late Pleistocene ◽  
Thermal State ◽  
Regional Scale ◽  
Distribution Data ◽  
Laptev Sea ◽  
Western Coast ◽  
Radiocarbon Dates ◽  
South Central ◽  
Ice Complex

Abstract. The composition of permafrost deposits holds information on the paleo-environment during and following deposition. Sampling natural exposures and drilling are two methods used to access permafrost archives. In this study, we combine both approaches at the western coast of the Buor Khaya Peninsula in the south-central Laptev Sea (Siberia) to study late Pleistocene permafrost; namely the Yedoma Ice Complex (IC), which is prominent across much of eastern Siberia. Two Yedoma IC exposures and one drill core were studied for cryolithological (i.e. ice and sediment features), geochemical, and geochronological parameters. Borehole temperatures were measured for three years to capture the current thermal state of permafrost. The studied sequences were composed of ice-oversaturated silts and fine-grained sands with considerable amounts of organic matter (0.2 to 24 wt %). Syngenetic ice wedges intersect the frozen deposits. The deposition of the Yedoma IC, as revealed by radiocarbon dates of sedimentary organic matter, took place between 54.1 and 30.1 kyr BP. Continued Yedoma IC deposition until about 14.7 kyr BP is shown by dates from organic matter preserved in ice-wedge ice. For the lowermost and oldest Yedoma IC part, infrared-stimulated luminescence dates on feldspar show deposition ages between 51.1 ± 4.9 and 44.2 ± 3.6 kyr BP. End-member modelling was applied to grain-size-distribution data to unmix sedimentation processes during Yedoma IC formation. Three to five statistical end-members were detected within Yedoma IC deposits of different ages, which we interpret as signals of alluvial, proluvial, and aeolian transport and redeposition as well as in-situ frost weathering in a polygonal tundra landscape. The study captures the internal variation of Yedoma IC characteristics and puts its local stratigraphy into regional scale. The cryolithological inventory of the Yedoma IC preserved on the Buor Khaya Peninsula is closely related to the results of other IC studies, for example, to the west on the Bykovsky Peninsula, where formation time (mainly during the late Pleistocene MIS 3 interstadial) and conditions were similar. Local freezing conditions on Buor Khaya, however, differed, and created solute-enriched (salty) and isotopically-light porewater pointing to deep active-layer and thaw-bulb freezing after deposition. Due to intense coastal erosion, the biogeochemical signature of the studied Yedoma IC represents the terrestrial end-member for, and is closely related to organic matter currently being deposited in the marine realm of the Laptev Sea shelf.

scholarly journals Implications of Radiocarbon Dates from Potter Creek Cave, Shasta County, California, USA

Radiocarbon ◽  
2009 ◽  
Vol 51 (3) ◽  
pp. 931-936 ◽  
Author(s):  
Robert S Feranec
Keyword(s):  
Late Pleistocene ◽  
Bone Collagen ◽  
Radiocarbon Dates ◽  
The North ◽  
Terminal Pleistocene ◽  
Shasta County

New dates obtained from the bone collagen of mammals from the deposits in Potter Creek Cave, Shasta County, California, USA, show that these fossils were emplaced over the last 30,000 yr. The dates support the assignment of the fauna in the cave to the late Pleistocene and are contemporaneous to the dates obtained from the fauna of Samwel Cave located 5 km to the north. These new dates do not support previous radiocarbon dates suggesting a Holocene extinction of the extinct bovid Euceratherium collinum, and demonstrate that this and other megafauna were not present in the vicinity after the terminal Pleistocene.

scholarly journals Calibration of Radiocarbon Dates for the Late Pleistocene Using U/Th Dates on Stalagmites

Radiocarbon ◽  
1997 ◽  
Vol 39 (1) ◽  
pp. 27-32 ◽  
Author(s):  
John C. Vogel ◽  
Joel Kronfeld
Keyword(s):  
South Africa ◽  
Magnetic Dipole ◽  
Satisfactory Agreement ◽  
Late Pleistocene ◽  
Calibration Curve ◽  
Dipole Field ◽  
Radiocarbon Dates ◽  
The Past ◽  
The Earth ◽  
Magnetic Dipole Field

Twenty paired 14C and U/Th dates covering most of the past 50,000 yr have been obtained on a stalagmite from the Cango Caves in South Africa as well as some additional age-pairs on two stalagmites from Tasmania that partially fill a gap between 7 ka and 17 ka ago. After allowance is made for the initial apparent 14C ages, the age-pairs between 7 ka and 20 ka show satisfactory agreement with the coral data of Bard et al. (1990, 1993). The results for the Cango stalagmite between 25 ka and 50 ka show the 14C dates to be substantially younger than the U/Th dates except at 49 ka and 29 ka, where near correspondence occurs. The discrepancies may be explained by variations in 14C production caused by changes in the magnetic dipole field of the Earth. A tentative calibration curve for this period is offered.

Influence of motilin and cholecystokinin on sphincter of Oddi and duodenal mobility

1987 ◽  
Vol 253 (5) ◽  
pp. G679-G683 ◽  
Author(s):  
E. L. Muller ◽  
P. A. Grace ◽  
R. L. Conter ◽  
J. J. Roslyn ◽  
H. A. Pitt
Keyword(s):  
Sphincter Of Oddi ◽  
Prairie Dogs ◽  
Prairie Dog ◽  
Cholecystokinin Octapeptide ◽  
Side Hole ◽  
Hole Pressure ◽  
Duodenal Motility ◽  
Sphincter Of Oddi Motility ◽  
Duodenal Lumen ◽  
Distal Port

The sphincter of Oddi and the duodenum exhibit cyclical activity in phase with the migrating myoelectric complex. Both motilin and cholecystokinin have been shown to modulate gastrointestinal and sphincter of Oddi motility. However, previous studies have not monitored the effects of these hormones on simultaneously recorded sphincter of Oddi and duodenum pressures. The present investigation was undertaken, therefore, to determine the influence of both motilin and cholecystokinin on simultaneously recorded sphincter of Oddi and duodenal motility. In seven anesthetized prairie dogs, a triple-lumen, side-hole, pressure-monitored perfusion catheter was positioned with the proximal port in the sphincter of Oddi and the distal port in the duodenal lumen. Sphincter of Oddi and duodenal motility was recorded before and during 20-min infusions of motilin and cholecystokinin octapeptide (CCK-8) at 1, 10, and 100 ng.kg-1.min-1. Both hormones produced dose-related increases in sphincter of Oddi and duodenal motility. No response was observed with either hormone at 1 ng.kg-1.min-1. At 10 ng.kg-1.min-1, the duodenum was slightly more sensitive to motilin than to CCK-8, while the sphincter of Oddi was equally affected by both hormones. At 100 ng.kg-1.min-1, both hormones stimulated the sphincter of Oddi and the duodenum equally. These data indicate that in the prairie dog, both motilin and cholecystokinin stimulate sphincter of Oddi and duodenal motility.

The Hayes Tephra Deposits, and Upper Holocene Marker Horizon in South-Central Alaska

1990 ◽  
Vol 33 (3) ◽  
pp. 276-290 ◽  
Author(s):  
James R. Riehle ◽  
Peter M. Bowers ◽  
Thomas A. Ager
Keyword(s):  
Cook Inlet ◽  
Radiocarbon Dates ◽  
Fine Grained ◽  
South Central ◽  
Inlet Region ◽  
Tephra Deposits ◽  
Phenocryst Content

AbstractThe most widespread of all Holocene tephra deposits in the Cook Inlet region of south-central Alaska is a set of deposits from Hayes volcano. Because of their unique phenocryst content—biotite in rare amounts and a high proportion of amphibole to pyroxene—the deposits are readily identifiable at all but the most distant sites where they are very fine grained. Eighteen radiocarbon dates from eight upland sites limit the age of the tephra set to between about 3500 and 3800 yr. The set originated at Hayes volcano in the Tordrillo Mountains 150 km northwest of Anchorage; seven or possibly eight closely succeeding deposits, low-silica dacite in composition, compose two main lobes that extend northeast for 400 km and south for at least 250 km from the vent. We estimate the total tephra volume to be 10 km3; multiple layers imply four to six larger and two or three smaller eruptions. The deposits are a nearly isochronous marker horizon that should be useful in future archeologic, geologic, and palynologic studies in the region.

Late Pleistocene chronology and paleoclimate of Vancouver Island determined from cave deposits

1981 ◽  
Vol 18 (11) ◽  
pp. 1643-1652 ◽  
Author(s):  
M. Gascoyne ◽  
D. C. Ford ◽  
H. P. Schwarcz
Keyword(s):  
Late Pleistocene ◽  
Growth Period ◽  
Vancouver Island ◽  
Isotopic Equilibrium ◽  
South Central ◽  
Cave Deposits ◽  
Short Period ◽  
Thermal Buffering

Speleothems from four caves in south-central Vancouver Island have been analysed by the 230Th/234U method. Only speleothems from one cave, Cascade Cave, near Port Alberni, contained sufficient uranium for them to be dated. Twenty-seven ages determined for seven speleothems were found to cluster in two periods: 67–28 ka, corresponding to the Olympia interstadial, and <23–10 ka (or <15 ka if corrected for detrital thorium contamination), corresponding to the Fraser (late Wisconsin) deglaciation and Holocene periods. Two speleothems were found to be deposited in isotopic equilibrium with their seepage waters. Profiles of variations in δ18O of the calcite (δ18Oc) of each of the two deposits show a decrease of 1.3‰ over the growth period, 64–28 ka. At all times, δ18Oc was less than δ18O of modern calcite in the cave. Using modern cave temperature and the variation of δ18O of seawater over the dated period, the profiles of δ18Oc are interpreted in terms of a paleotemperature record for the Olympia interstadial in Vancouver Island. The results show a gradual cooling from 4 °C at 64 ka, to 0 °C between 35 and 28 ka. These results are consistent with conditions necessary for speleothem growth and with published work on surficial Wisconsin deposits in the area. No distinct, short-period warming or cooling events are seen in the record, probably due to thermal buffering by the adjacent ocean.

Radiocarbon Dating and Dietary Stable Isotope Analysis of Kwaday Dän Ts'inchí

2007 ◽  
Vol 72 (4) ◽  
pp. 719-734 ◽  
Author(s):  
Michael P. Richards ◽  
Sheila Greer ◽  
Lorna T. Corr ◽  
Owen Beattie ◽  
Alexander Mackie ◽  
...  
Keyword(s):  
Radiocarbon Dating ◽  
Isotope Analysis ◽  
Human Remains ◽  
Isotopic Analysis ◽  
High Elevation ◽  
Bone Collagen ◽  
Contact Period ◽  
European Contact ◽  
Ams Dating ◽  
The Individual

We report here on the results of AMS dating and isotopic analysis of the frozen human remains named Kwaday Dän Ts'inchí and associated materials recovered from a glacier located in Northwest British Columbia, Canada in 1999. The isotopic analysis of bone collagen (bulk and single amino acids) from the individual indicates a strongly marine diet, which was unexpected given the location of this find, more than 100 km inland eroding out of a high elevation glacier; however, bulk hair and bone cholesterol isotopic values indicate a shift in diet to include more terrestrial foods in the year before death. The radiocarbon dating is not straightforward, as there are difficulties in determining the appropriate marine correction for the human remains, and the spread of dates on the associated artifacts clearly indicates that this was not a single use site. By combining the most recent date on a robe worn by Kwaday Dän Ts'inchi with direct bone collagen dates we conclude that the individual likely dates to between cal A.D. 1670 to 1850, which is in the pre-(or early) European contact period for this region.

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