Reworked Middle Wisconsinan (?) plant fossils from the Brampton Esker, southern Ontario

1977 ◽  
Vol 14 (3) ◽  
pp. 426-430 ◽  
Author(s):  
P. F. Karrow ◽  
W. Harrison ◽  
H. C. Saunderson
Keyword(s):  
Boreal Forest ◽  
Radiocarbon Date ◽  
Glacial Deposits ◽  
Radiocarbon Dates ◽  
Southern Ontario ◽  
Plant Fossils ◽  
Gravel Pit

Plant fossils, consisting of abraded pieces of wood, seeds, and pollen, occur near the bottom of the Armbro gravel pit in a till-capped esker near Brampton, Ontario. A radiocarbon date suggests a Mid-Wisconsinan age for the wood, whereas stratigraphic evidence suggests a Port Huron age for the enclosing sediments. The plant fossils indicate conditions similar to those now found in the southern boreal forest. Derivation of the plants from buried Middle Wisconsinan interstadial sediments to the southeast is suggested.Plant remains in glacial deposits should normally be assumed to be reworked; radiocarbon dates on such fossils do not date the enclosing sediment.

New Light on the Midland Discovery

1959 ◽  
Vol 25 (1) ◽  
pp. 66-78 ◽  
Author(s):  
Fred Wendorf ◽  
Alex D. Krieger
Keyword(s):  
Small Mammals ◽  
Radiocarbon Date ◽  
High Plains ◽  
Faunal Assemblage ◽  
Southern High Plains ◽  
Stratigraphic Sequence ◽  
Radiocarbon Dates ◽  
Cultural Events ◽  
Animal Bones

AbstractAdditional excavation in 1955 confirmed the previously reported stratigraphic sequence at Midland, Texas. Within the gray sand, which had yielded a fragmentary human calvarium, there were found additional flint flakes, burned rocks, and animal bones. Besides several small mammals, a four-horned antelope (probably Capromeryx) was present in the gray sand; horse bones occurred in the gray sand and overlying red sand. These finds make the two radiocarbon dates published in the 1955 Midland report, giving an age of about 7000 years to the gray sand, even less acceptable than previously thought. Experimental dating by the uranium daughter products technique suggests an age of about 20,000 years for the gray sand, somewhat excessive in terms of cultural correlations although supported by a single radiocarbon date and not unreasonable for the faunal assemblage. Ten radiocarbon dates from the Midland, Blackwater Draw, Lubbock Lake, and Plainview sites are discussed in terms of three possible correlations of the geological, climatic, faunal, and cultural events in the Southern High Plains.

Pleistocene Mammals from Gold Run Creek, Yukon Territory

1973 ◽  
Vol 10 (5) ◽  
pp. 697-759 ◽  
Author(s):  
C. R. Harington ◽  
F. V. Clulow
Keyword(s):  
Yukon Territory ◽  
Radiocarbon Date ◽  
Common Elements ◽  
Radiocarbon Dates ◽  
Equus Asinus ◽  
Wild Ass ◽  
Pleistocene Mammals ◽  
First Time

Remains of thirteen species of mammals are reported from Pleistocene deposits at Gold Run Creek near Dawson, Yukon Territory. Eight of the thirteen species are extinct and two are no longer living in the Yukon. The most common elements of the fauna are Equus (Asinus) lambei (Yukon wild ass), and Bison crassicornis (large-horned bison). Taxidea (badger) and Bison alaskensis (Alaskan bison) are reported for the first time from the Yukon Pleistocene. A kiang-like horse is also reported from deposits at Gold Run Creek.These mammals may have inhabited a cool grassland or open parkland during late Wisconsin time. Bison crassicornis and mammoth bone from deposits at Gold Run Creek have yielded radiocarbon dates of 22 200 ± 1400 yr B.P. and 32 250 ± 1750 yr B.P. respectively. Bison alaskensis is evidently older than the remainder of the fauna as bone from the specimen yielded a radiocarbon date of over 39 900 yr B.P.

scholarly journals Evaluating Bayesian radiocarbon-dated event-count [REC] models for the study of long-term human and environmental processes

2020 ◽  
Author(s):  
William Christopher Carleton
Keyword(s):  
Forest Fires ◽  
Simulated Data ◽  
Radiocarbon Date ◽  
Radiocarbon Dates ◽  
New Class ◽  
Environmental Processes ◽  
Growth Decline ◽  
Marine Ingression ◽  
Event Times

Chronological uncertainty complicates attempts to use radiocarbon dates as proxies for processes like human population growth/decline, forest fires, and marine ingression. Established approaches involve turning databases of radiocarbon-date densities into single summary proxies that cannot fully account for chronological uncertainty. Here, I use simulated data to explore an alternate Bayesian approach that instead models the data as what they are, namely radiocarbon-dated event-counts. The approach involves assessing possible event-count sequences by sampling radiocarbon date densities and then applying MCMC to estimate the parameters of an appropriate count-based regression model. The regressions based on individual sampled sequences were placed in a multilevel framework, which allowed for the estimation of hyperparameters that account for chronological uncertainty in individual event times. Two processes were used to produce simulated data. One represented a simple monotonic change in event-counts and the other was based on a real palaeoclimate proxy record. In both cases, the method produced estimates that had the correct sign and were consistently biased toward zero. These results indicate that the approach is widely applicable and could form the basis of a new class of quantitative models for use in exploring long-term human and environmental processes.

Insect faunas of late Devensian and Flandrian age from Church Stretton, Shropshire

1972 ◽  
Vol 263 (852) ◽  
pp. 327-367 ◽  
Keyword(s):  
Pollen Analysis ◽  
Thermal Environment ◽  
Radiocarbon Date ◽  
Radiocarbon Dates ◽  
Number Of Species ◽  
Summer Temperatures ◽  
Zone Ii ◽  
Climatic Optimum ◽  
The Church

Invertebrate faunas consisting mainly of insects, from deposits in the Church Stretton valley, are described and discussed. These deposits fall into two periods: ( a ) Late Devensian, which follows an episode of glaciation and precedes a period of accumulation of frost-shattered gravel fans; and ( b ) Flandrian, which post-dates the gravels and has been placed in the post-Glacial pollen zones VI and VII. The faunas of these two episodes are dealt with separately in Parts I and II respectively. Part I. From two sites in which sequences containing clays, peats and silts were examined five radiocarbon dates are available, the oldest being 13 555 ± 620 years B.P. and the most recent 11 000 ± 200 years B.P. The faunas include a substantial number of species not now found in Shropshire, many not in Britain. Inferences on the changing ecology and thermal environment of the area are drawn from these faunas and are compared with the pollen analytical zones. This comparison shows that, according to the insects, the warmest part of the episode was late zone I, and that zone II (the Allerod), often considered to be the climatic optimum of the period, appears to have been a time of gradually deteriorating summer temperatures. Part II. Deposits from three late Flandrian sites are discussed. Although only one radiocarbon date was obtained, of 8101 ± 138 years B.P., pollen analysis was carried out by Rowlands throughout each sequence and this showed that the earliest deposit, at Little Stretton, dated from zone VI a and at all three localities deposition continued into zone VII b. An examination of the insect assemblages shows that completely different biotopes, from open pasture to dense woodland, were existing side by side in the Church Stretton valley in late Flandrian time. Summer temperatures at least as high as those of today are inferred. The possibility exists that during the period represented here the climate was even warmer than that of the present but until more information is available it is not possible to be more definite on this point.

South American Radiocarbon Dates

1951 ◽  
Vol 8 ◽  
pp. 37-49 ◽  
Author(s):  
Junius Bird
Keyword(s):  
Time Span ◽  
Radiocarbon Date ◽  
South American ◽  
Radiocarbon Dates ◽  
Good Basis

The Stratigraphic data on some of the Peruvian samples provide a fairly good basis for evaluating the radiocarbon date measurements in relation to each other. The accompanying chart (Fig. 1) was prepared to clarify what is bound to be tedious reading. On it the plotting of the radiocarbon dates is obvious. The insertion with them of sectional profiles of midden excavations may be confusing, but does show where the tested material was found. In one instance (382), although the tested sample did not come from this midden, it belongs chronologically at the level indicated. Knowledge of the nature of the structure between the various layers gives us further means of assessing the results. Thus it is possible to compare the date blocks, as we might call the total plus and minus time span, and to point out which portions cannot be reconciled and are therefore impossible and which portions are improbable. The remaining segments mark the periods within which the actual dates are most likely to fall.

scholarly journals An ancient bison from the mouth of the Rauchua River (Chukotka, Russia)

2015 ◽  
Vol 84 (2) ◽  
pp. 232-245 ◽  
Author(s):  
Irina V. Kirillova ◽  
Oksana G. Zanina ◽  
Olga F. Chernova ◽  
Elena G. Lapteva ◽  
Svetlana S. Trofimova ◽  
...  
Keyword(s):  
Mitochondrial Dna ◽  
Stomach Contents ◽  
Early Holocene ◽  
Radiocarbon Date ◽  
Radiocarbon Dates ◽  
Limb Bones ◽  
Dna Analyses ◽  
Hind Limbs ◽  
Sem Study ◽  
Steppe Bison

An incomplete carcass of an extinct bison, Bison ex gr. priscus, was discovered in 2012 in the mouth of the Rauchua River (69°30′N, 166°49′E), Chukotka. The carcass included the rump with two hind limbs, ribs, and large flap of hide from the abdomen and sides, several vertebrae, bones of the forelimbs and anterior autopodia, stomach with its contents, and wool. The limb bones are relatively gracile, which is unusual in bison, and a SEM study of the hair microstructure suggests higher insulating capacity than in extant members of the genus. Additionally, mitochondrial DNA analyses indicate that the Rauchua bison belonged to a distinct and previously unidentified lineage of steppe bison. Two radiocarbon dates suggest a Holocene age for the bison: a traditional 14C date provided an estimate of 8030 ± 70 14C yr ВР (SPb-743) and an AMS radiocarbon date provided an age of 9497 ± 92 14C yr BP (AA101271). These dates make this the youngest known bison from Chukotka. Analysis of stomach contents revealed a diet of herbaceous plants (meadow grasses and sedges) and shrubs, suggesting that the early Holocene vegetation near the mouth of the Rauchua River was similar to that of the present day: tundra-associated vegetation with undersized plants.

Isotopic and geochemical composition of marl lake waters and implications for radiocarbon dating of marl lake sediments

1983 ◽  
Vol 20 (4) ◽  
pp. 599-615 ◽  
Author(s):  
J. V. Turner ◽  
P. Fritz ◽  
P. F. Karrow ◽  
B. G. Warner
Keyword(s):  
Inorganic Carbon ◽  
Dissolved Inorganic Carbon ◽  
Sediment Cores ◽  
Geochemical Composition ◽  
Radiocarbon Dates ◽  
Southern Ontario ◽  
Suitable Material ◽  
Geochemical Parameters ◽  
Marl Lake ◽  
Lake Waters

Radiocarbon dates on organic and calcareous fractions of sediment cores from marl lakes may yield anomalous ages due to the assumption of a constant hardwater correction factor along the sediment sequence. A study of eight marl lakes in southern Ontario that are actively precipitating calcium carbonate was conducted in order to assess those isotopic and aqueous geochemical parameters in modern lakes that may be utilized to estimate the history and extent of variations in the hardwater effect along such sediment sequences. Results show an increase in the δ13C composition of lake DIC (dissolved inorganic carbon) as approach to isotopic equilibrium with atmospheric CO2 occurs. Differences in the extent to which this equilibrium is established also appear responsible for observed differences in the 14C activity of DIC between lakes of as much as 20 pmc (percent modern carbon). These variations have been related to the relative residence times of water in each lake by examination of their corresponding seasonal variations in 18O and 2H content. Consequently δ13C and δ18O of marl and molluscs have been used to identify variations in the hardwater effect along the sediment profile. A profile of radiocarbon dates on marl from Little Lake in southern Ontario shows satisfactory agreement with an independently determined pollen chronology. Where certain criteria are met, marl deposits appear to be suitable material for establishing Quaternary chronology.

Stratigraphy, Paleontology, and Age of Lake Algonquin Sediments in Southwestern Ontario, Canada

1975 ◽  
Vol 5 (1) ◽  
pp. 49-87 ◽  
Author(s):  
P.F. Karrow ◽  
T.W. Anderson ◽  
A.H. Clarke ◽  
L.D. Delorme ◽  
M.R. Sreenivasa
Keyword(s):  
Lake Michigan ◽  
Critical Evaluation ◽  
Plant Macrofossils ◽  
Supporting Evidence ◽  
Radiocarbon Dates ◽  
Southern Ontario ◽  
Alluvial Sediments ◽  
The North ◽  
Lake Algonquin ◽  
Water Stage

AbstractMolluscs, ostracodes, diatoms, pollen, plant macrofossils, peat, and wood have been found in glacial Lake Algonquin sediments, and estuarine-alluvial sediments of the same age, in southern Ontario. Molluscs and ostracodes are particularly abundant and widespread. Pollen analysis of Lake Algonquin sediments, bogs on the Algonquin terrace, and upland bogs above the Algonquin terrace, indicate that Lake Algonquin was still in existence at the time of the spruce-pine pollen transition, previously dated at an average of 10,600 yr BP at a number of sites in Michigan, Ohio, and southern Ontario. Wood in estuarine-alluvial sediments graded to the Algonquin level is of similar radiocarbon age. Evidence from several sites in the eastern Great Lakes area suggests the presence of a preceding low-water stage (Kirkfield outlet stage); drowned and alluviated valleys and fining-upward sediment sequences have been identified in this study as further supporting evidence. Lake Algonquin drained from the southern sites by isostatic tilting and eventual opening of the “North Bay outlet” some time shortly after 10,400 yr BP.Our radiocarbon dates suggest the low-water stage has an age of about 11,000 yr BP, and that Lake Algonquin drained 10,000–15,000 y. a. Dates previously published for the Lake Michigan basin are generally too young in comparison with ours, and dates on the Champlain Sea are generally too old. More critical evaluation of all dating results is desirable.From fossil remains we suggest a rapidly expanding fauna in the waters of Lake Algonquin. The spruce pollen period was a time of rapid faunal and floral migration, when the ice front was retreating from Kirkfield to North Bay, Ontario. Diversity of some species and fossil numbers increased substantially at the transition from spruce to pine just before Lake Algonquin drained.

Excavations and Metal-working at Llwyn Bryn-dinas Hillfort, Llangedwyn, Clwyd

1992 ◽  
Vol 58 (1) ◽  
pp. 265-283 ◽  
Author(s):  
C. R. Musson ◽  
W. J. Britnell ◽  
J. P. Northover ◽  
C. J. Salter ◽  
P. Q. Dresser ◽  
...  
Keyword(s):  
Bronze Age ◽  
Iron Age ◽  
Copper Alloy ◽  
Radiocarbon Date ◽  
Small Scale ◽  
Metal Working ◽  
Radiocarbon Dates ◽  
Alloy Casting ◽  
The North ◽  
Local Evidence

Small-scale rescue excavations at Llwyn Bryn-dinas hillfort, on the Welsh Borderland, showed that the earliest fortification belonged to the late Bronze Age, with radiocarbon dates in the late 9th and 8th centuries be. A terrace, subsequently cut into the rear of the rampart to accommodate a metal-working floor, was associated with a radiocarbon date centred in the late 3rd century bc. Detailed analysis of the metal-working debris suggests that copper-alloy casting, iron forging and possibly bronze production were carried out within a single workshop. The finds include a distinctive form of handled crucible. The industry appears to have been fairly small-scale, of short duration, and probably only designed to meet the internal needs of the hillfort population. The excavation adds significantly to the local evidence for metal-working during the later prehistoric period. A distinctive zinc-impurity pattern in the copper alloy and raw copper, previously identified in material from other sites nearby, confirms the suggestion of an Iron Age bronze-working industry based on a specific metal source in the north Powys area. In addition, analysis of the iron-working debris suggests the exploitation of a distinctive local ore body. The metal-working activity appears to have come to an abrupt end, possibly with the enlargement or local repair of the rampart. Later phases of activity include a final occupation deposit with an associated radiocarbon date centred in the mid 2nd century bc.

Late Pleistocene northward-dispersing Bison antiquus from the Bighill Creek Formation, Gallelli Gravel Pit, Alberta, Canada, and the fate of Bison occidentalis

2008 ◽  
Vol 45 (7) ◽  
pp. 827-859 ◽  
Author(s):  
Michael C. Wilson ◽  
Leonard V. Hills ◽  
Beth Shapiro
Keyword(s):  
Late Pleistocene ◽  
Type Specimen ◽  
Radiocarbon Dates ◽  
Dna Evidence ◽  
Large Size ◽  
Gravel Pit ◽  
Ice Retreat ◽  
America South ◽  
Bison Antiquus ◽  
Clade 1

Late Pleistocene bison skeletal remains from the Gallelli Gravel Pit in the Bighill Creek Formation at Calgary, Alberta, document at least two individuals, including the largest postglacial bison reported from North America south of Beringia. Two partial crania, dated to 11 290 and 10 100 14C years BP, are referred to the southern species Bison antiquus Leidy, indicating northward movement from the midcontinent as ice retreat opened a corridor between Laurentide and Cordilleran ice. Their large size suggests a dispersal phenotype exploiting newly available territory. DNA evidence links the 11 290-year-old bison to Clade 1, which includes modern B. bison . This supports in situ evolution of B. bison from B. antiquus through the intermediate usually called B.“occidentalis” . Bison of B. “occidentalis” character appeared in Alberta about 10 ka BP, and the DNA evidence counters the suggestion of a migratory wave from Beringia. The B. occidentalis type specimen is from Alaska, so this name may be inappropriate for southern populations. Radiocarbon dates suggest that the Bighill Creek Formation paleofauna comprises two faunules separated in time by the Younger Dryas climatic episode.

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