Late Quaternary glaciation in the Northern Ogilvie Mountains: revised correlations and implications for the stratigraphic record

2002 ◽  
Vol 39 (11) ◽  
pp. 1709-1717 ◽  
Author(s):  
Brandon D Beierle
Keyword(s):  
Late Quaternary ◽  
Sediment Cores ◽  
Late Glacial ◽  
Yukon Territory ◽  
Radiocarbon Dates ◽  
Terminal Moraine ◽  
Base Level ◽  
Quaternary Glaciation ◽  
Radiocarbon Data ◽  
Blackstone River

New geomorphic, paleolimnological, and radiocarbon data suggest that a terminal moraine complex in the Northern Ogilvie Mountains, Yukon Territory, Canada, may represent the McConnell Glaciation (Late Wisconsinan), rather than the Reid Glaciation (marine isotope Stage 8; Illinoian) as previously thought. Relict fluvial channels on the surface of the moraine and analysis of a suite of lake sediment cores from Chapman Lake, a closed-basin kettle on the surface of the moraine, suggest that flow from the Blackstone River passed over the moraine and through the lake until ca. 12 500 BP, at which time the Blackstone River was captured by the East Blackstone River, diverting flow from the lake. Subsequent incision by the Blackstone River has left its base level more than 10 m below the level of Chapman Lake. Perched former outlets from Chapman Lake indicate that this incision must postdate stream capture. Because the Chapman Lake moraine is a topographic barrier across the Blackstone River valley, incision must have occurred shortly after deposition of the moraine, suggesting that the landscape surrounding Chapman Lake is substantially younger than previously thought. Additional radiocarbon dates also suggest that kettle subsidence at Chapman Lake was ongoing during the early Holocene and that North Fork Pass moraine, 15 km upvalley from the Chapman Lake moraine, may have been formed during the Late Glacial rather than the McConnell Glaciation.

Late Quaternary Vegetation and Climate of Southern Tierra del Fuego

1989 ◽  
Vol 31 (3) ◽  
pp. 396-406 ◽  
Author(s):  
Calvin J. Heusser
Keyword(s):  
Late Quaternary ◽  
Pollen Dispersal ◽  
Late Glacial ◽  
Tierra Del Fuego ◽  
Fossil Pollen ◽  
Radiocarbon Dates ◽  
Modern Pollen ◽  
Open Woodland ◽  
Glacial Time ◽  
Vegetation And Climate

AbstractVegetation and climate over approximately the past 13,000 yr are reconstructed from fossil pollen in a 9.4-m mire section at Caleta Róbalo on Beagle Channel, Isla Navarino (54°56′S, 67°38′W), southern Tierra del Fuego. Fifty surface samples reflecting modern pollen dispersal serve to interpret the record. Chronologically controlled by nine radiocarbon dates, fossil pollen assemblages are: Empetrum-Gramineae-Gunnera-Tubuliflorae (zone 3b, 13,000–11,850 yr B.P.), Gramineae-Empetrum-assorted minor taxa (zone 3a, 11,850-10,000 yr B.P.), Nothofagus-Gramineae-Tubuliflorae-Polypodiaceae (zone 2, 10,000–5000 yr B.P.), Nothofagus-Empetrum (zone 1b, 5000-3000 yr B.P.), and Empetrum-Nothofagus (zone 1a, 3000-0 yr B.P.). Assemblages show tundra under a cold, dry climate (zone 3), followed by open woodland (zone 2), as conditions became warmer and less dry, and later, with greater humidity and lower temperatures, by closed forest and the spread of mires (zone 1). Comparisons drawn with records from Antarctica, New Zealand, Tasmania, and the subantarctic islands demonstrate broadly uniform conditions in the circumpolar Southern Hemisphere. The influences of continental and maritime antarctic air masses were apparently considerable in Tierra del Fuego during cold late-glacial time, whereas Holocene climate was largely regulated by interplay between maritime polar and maritime tropical air.

Antiquity of Man at Anaktuvuk Pass, Alaska

1964 ◽  
Vol 29 (4) ◽  
pp. 493-496 ◽  
Author(s):  
Stephen C. Porter
Keyword(s):  
Late Glacial ◽  
Valley Floor ◽  
Archaeological Sites ◽  
Advanced Stage ◽  
Radiocarbon Dates ◽  
Glacial Sediments ◽  
Terminal Moraine ◽  
Probable Time

AbstractGeologic evidence from Anaktuvuk Pass indicates that the latest ice advance during the Itkillik glaciation reached its maximum stand between 8000 and 9000 years ago. Archaeological sites at the pass lie behind a terminal moraine built during this advance and therefore must postdate it. In view of the probable time involved for deglaciation, habitable ice-free areas near the axis of the valley could not have been available for campsites until an advanced stage of ice wastage. Radiocarbon dates indicate that deglaciated areas existed near the present drainage divide as early as 7200 years ago, but prior to that time the valley floor was largely buried under stagnant ice. Although certain archaeological complexes have been interpreted on the basis of typology as evidencing considerable antiquity, the geologic relationships between the sites and radiocarbon-dated, late-glacial sediments places a maximum limiting age of about 7000 years on the oldest cultural materials.

A submerged late-Quaternary deposit at Roddans Port on the north-east coast of Ireland

1965 ◽  
Vol 249 (758) ◽  
pp. 221-255 ◽  
Keyword(s):  
Local Development ◽  
Late Quaternary ◽  
Algal Species ◽  
Late Glacial ◽  
Red Clay ◽  
Quaternary Deposit ◽  
Radiocarbon Dates ◽  
North East ◽  
The North ◽  
Pollen Analyses

Recent coastal erosion has cut into the filling of a former inter-drumlin lake and exposed an excellent sequence of Late-glacial deposits. These have been investigated by pollen analyses, identification of seeds, Mollusca, ostracods, and Algae; by stratigraphic studies and by radiocarbon dating. The coincidence of all this evidence strongly confirms that the greater part of the depositional sequence embraces the north-west European Late-glacial stages of the Older and Younger Dryas or Salix herbacea clays, with the intervening milder Allerod oscillation. This sequence is overlain by a small thickness of Post-glacial peat. The Late- and Post-glacial filling is shown to be sandwiched between deposits laid down during two phases of marine submergence; the earlier transgression is represented by a red marine clay which had a widespread occurrence on the Co. Down coast, and the later transgression is represented by the local development of the Postglacial raised beach. The pollen analyses from the close sampling of the organic Allerød phase muds have yielded unusually detailed data on vegetational conditions in the Late-glacial period. The radiocarbon dates, while fully confirming the age attribution, have not enough precision to give a close measure of the duration of the Allerød phase. The pollen evidence on vegetation and climate is augmented and clarified by identifications of seeds, shells, ostracods and Algae. The ostracods confirm the marine character of the early red clay, and freshwater shells were found in the overlying Allerød mud. The algal species from the Late-glacial layers have been compared with recent algal floras from Ireland, and with those found in Late- and Inter-glacial sediments elsewhere. The most notable feature is the prominence of species representative of a base-rich habitat.

scholarly journals Late Quaternary Pollen Records and Vegetation History of the Southwest Yukon Territory: A Review

2007 ◽  
Vol 45 (2) ◽  
pp. 175-193 ◽  
Author(s):  
Xia-Cheng Wang ◽  
Marie-Anne Geurts
Keyword(s):  
Vegetation History ◽  
Late Quaternary ◽  
Late Glacial ◽  
Yukon Territory ◽  
Circulation System ◽  
Spruce Forest ◽  
Migration Routes ◽  
Shrub Tundra ◽  
History Of ◽  
Pollen Records

ABSTRACTThis paper is a summary of all known late Quaternary palynostratigraphic records from the southwest Yukon Territory. Thirty two pollen sites available by the end of 1988 are reviewed. Most pollen records in the region are of Holocene age. During the late-glacial to early Holocene, the southwest Yukon supported a herb-dominated tundra vegetation which was replaced by a birch-dominated shrub-tundra at about 10,000 yr BP. Spruce invaded the area between 9000 and 8600 yr BP at different localities, and a southward time transgression is visible in the Aishihik Basin. The current regional vegetation has been stable since 7600-8000 yr BP when dense spruce forest and/or spruce forest-tundra was established in most localities. In the Snag area, however, dense spruce forest developed only around 5700 yr BP, which is about 2000 years later than in the Aishihik Basin. The exotic pine pollen records in the region exhibit an interesting pattern, suggesting a frequent shift of the atmospheric circulation system. Anomalous records of alder pollen from the Aishihik Basin and adjacent regions suggest that alder has never been widespread in these areas due to aridity, and alder pollen is greatly overrepresented in pollen spectra. Spruce arrival dates suggest that further investigations in the Tintina Valley, Yukon River Valley, and Car-macks region might provide useful information concerning the spruce migration routes.

Late-Glacial Environmental Changes South of the Wisconsinan Terminal Moraine in the Eastern United States

2000 ◽  
Vol 53 (1) ◽  
pp. 105-113 ◽  
Author(s):  
Emily W.B. Russell ◽  
Scott D. Stanford
Keyword(s):  
Environmental Changes ◽  
Sediment Cores ◽  
Late Glacial ◽  
Cold Climate ◽  
Eastern United States ◽  
Forest Patches ◽  
Terminal Moraine ◽  
Arboreal Pollen ◽  
Land Surfaces ◽  
Glacial Time

AbstractPalynological analyses of two sediment cores, one 2.4 m long from northern Delaware, dated about 16,300 to 14,700 14C yr B.P., and one 1.8 m long from New Jersey just south of the Wisconsinan terminal moraine and dated about 13,600 to 12,500 14C yr B.P., give the first detailed evidence of vegetation in this area during these periods. The overall assemblages are similar to each other, with Picea and Pinus dominating the arboreal pollen and Poaceae and Cyperaceae the herbaceous flora. Nonarboreal pollen contributes about 30–50% of the total, indicating a very open vegetation or a mix of forest patches and open areas. Especially in Delaware, there is a diversity of other herbaceous pollen, including members of the Asteraceae, Fabaceae, and Ranunculaceae. The assemblages do not resemble current North American tundra or boreal forest assemblages; rather, they resemble assemblages characteristic of tundra on recently exposed land surfaces north of the Wisconsinan terminal moraine. The persistence of the assemblages for 1500–2000 years in late-glacial time suggests stable and cold climate during this time of glacier retreat.

Palaeoenvironmental reconstruction of late Quaternary foraminifera and molluscs from the ENEA borehole (Versilian plain, Tuscany, Italy)

2010 ◽  
Vol 74 (2) ◽  
pp. 265-276 ◽  
Author(s):  
M. Gabriella Carboni ◽  
Luisa Bergamin ◽  
Letizia Di Bella ◽  
Daniela Esu ◽  
Emanuela Pisegna Cerone ◽  
...  
Keyword(s):  
Sea Level ◽  
Late Quaternary ◽  
Central Italy ◽  
Vertical Displacement ◽  
Second Phase ◽  
Sea Level Changes ◽  
Radiocarbon Dates ◽  
Radiocarbon Data ◽  
Palaeoecological Reconstruction ◽  
Lagoon Environment

AbstractForaminifera and molluscs from the 90 m deep ENEA borehole (Versilian plain, central Italy) were studied for paleoenvironmental purposes. Palaeontological analyses, integrated with U/Th and radiocarbon data, helped to recognize late Quaternary sea-level changes and supplied results on tectonic mobility of the area. The study highlighted four sedimentary phases. The first phase consists of a shore environment attributed to MIS 7.1. A hiatus corresponding to MIS 6 is hypothesized at the top of this interval. Recognition of the paleo-shoreline of MIS 7.1 at − 72.8 m signifies a vertical displacement due to the extensional tectonics of the Apennine orogenesis. The second phase consists of a transgressive succession with evidence of warm temperatures, which was interpreted as part of the transgression leading to the MIS 5.5 highstand. The third phase includes sub-aerial and lacustrine deposits. Radiocarbon dates and palaeoecological reconstruction led us to attribute this interval to MIS 4, MIS 3 and MIS 2. The fourth phase begins with a lagoon environment attributable to Holocene sea-level rise and ends with marsh episodes, signifying the progradation of the alluvial plain. This reconstruction confirms the hypothesis of tectonic stability for the Versilian area during the Holocene.

scholarly journals Late Quaternary history of Lammefjorden, north-west Sjælland, Denmark

2020 ◽  
Author(s):  
Ole Bennike ◽  
Peter Roll Jakobsen ◽  
Jakob Walløe Hansen
Keyword(s):  
Late Quaternary ◽  
Sediment Cores ◽  
Late Glacial ◽  
Early Holocene ◽  
Last Deglaciation ◽  
North West ◽  
Najas Marina ◽  
Marine Deposits ◽  
Minimum Age ◽  
History Of

Lammefjorden is a reclaimed fjord in north-west Sjælland, Denmark. Sediment cores from the area were collected to study its development after the last deglaciation, in particular the sea-level history. Late glacial and Early Holocene lake and bog deposits occur below marine deposits. Sparse late glacial fossil assemblages indicate tree-less environments with dwarf-shrub heaths. Early Holocene deposits contain remains of Betula sec. Albae sp. and Pinus sylvestris, which indicate open forests. The wetland flora comprised the calciphilous reed plant Cladium mariscus and the water plant Najas marina. Marine gyttja from basins is characterised by sparse benthic faunas, probably due to high sedimentation rates. In some areas, shell-rich deposits were found, with large shells of Ostrea edulis, indicative of high summer temperatures, high salinity and strong tidal currents. A marine shell dated to 6.7 cal. ka provides a minimum age for the marine transgression of Lammefjorden.

Deglaciation, basin formation and post-glacial climate change from a regional network of sediment core sites in Ohio and eastern Indiana

2011 ◽  
Vol 76 (3) ◽  
pp. 401-410 ◽  
Author(s):  
Katherine C. Glover ◽  
Thomas V. Lowell ◽  
Gregory C. Wiles ◽  
Donald Pair ◽  
Patrick Applegate ◽  
...  
Keyword(s):  
Landscape Change ◽  
Environmental Changes ◽  
Sediment Cores ◽  
Ice Sheet ◽  
Ice Cores ◽  
Late Glacial ◽  
Radiocarbon Dates ◽  
Last Glacial ◽  
Ice Retreat ◽  
Basin Formation

AbstractMany paleoclimate and landscape change studies in the American Midwest have focused on the Late Glacial and early Holocene time periods (~ 16–11 ka), but little work has addressed landscape change in this area between the Last Glacial Maximum and the Late Glacial (~ 22–16 ka). Sediment cores were collected from 29 new lake and bog sites in Ohio and Indiana to address this gap. The basal radiocarbon dates from these cores show that initial ice retreat from the maximal last-glacial ice extent occurred by 22 ka, and numerous sites that are ~ 100 km inside this limit were exposed by 18.9 ka. Post-glacial environmental changes were identified as stratigraphic or biologic changes in select cores. The strongest signal occurs between 18.5 and 14.6 ka. These Midwestern events correspond with evidence to the northeast, suggesting that initial deglaciation of the ice sheet, and ensuing environmental changes, were episodic and rapid. Significantly, these changes predate the onset of the Bølling postglacial warming (14.8 ka) as recorded by the Greenland ice cores. Thus, deglaciation and landscape change around the southern margins of the Laurentide Ice Sheet happened ~ 7 ka before postglacial changes were felt in central Greenland.

A revised late-Quaternary vegetation history of the unglaciated southwestern Yukon Territory, Canada, from Antifreeze and Eikland ponds

2010 ◽  
Vol 47 (1) ◽  
pp. 75-88 ◽  
Author(s):  
Jesse C. Vermaire ◽  
Les C. Cwynar
Keyword(s):  
Vegetation Change ◽  
Vegetation History ◽  
Late Quaternary ◽  
Late Glacial ◽  
Yukon Territory ◽  
Early Holocene ◽  
Glacial Period ◽  
Vegetation Shifts ◽  
History Of ◽  
New Interpretation

Antifreeze Pond was thought to contain the oldest record of continuous environmental change in the southwestern Yukon. We have revised the original interpretation of the vegetation history of Antifreeze Pond and this region based on new pollen, stomate, and macrofossil analysis, along with 38 new accelerator mass spectrometry (AMS) 14C dates from Antifreeze Pond and nearby Eikland Pond. Although the overall pattern of vegetation change is similar to the previously published Antifreeze Pond record, our new analysis indicates that the timing of the major vegetation shifts is substantially different, particularly during the late-glacial and early Holocene periods (from ∼17 000 – 9000 cal years BP). The original Antifreeze Pond record was thought to span a mid-Wisconsinan interstadial (>30 000 cal years BP) and the full-glacial period. Our results, however, indicate that the material of mid-Wisconsinan age was likely deposited by slumping around the pond making interpretation of the paleoenvironment difficult. Furthermore, our AMS 14C dates show that what was thought to be a full-glacial vegetation record is actually the vegetation history of the late-glacial period (ca. 17 000 – 11 000 cal years BP), which was a time of rapid sediment deposition into the ponds. The Eikland Pond record has an early Holocene Populus rise between ca. 11 000 – 8000 cal years BP that is not present in either the new or original Antifreeze Pond records. This new interpretation of the vegetation history should aid comparisons to other regional paleoenvironmental records.

Vegetational and climatic history of Nova Scotia. I. Radiocarbon-dated pollen profiles from Halifax, Nova Scotia

1987 ◽  
Vol 65 (7) ◽  
pp. 1482-1490 ◽  
Author(s):  
J. Gordon Ogden III
Keyword(s):  
Nova Scotia ◽  
Sediment Cores ◽  
Birch Pollen ◽  
Late Glacial ◽  
Fagus Grandifolia ◽  
Radiocarbon Dates ◽  
Sediment Stratigraphy ◽  
Catchment Areas ◽  
Pollen Types ◽  
Open Country

Pollen and sediment stratigraphy of three lakes in the Halifax, N.S., area show similarities and differences related to morphometry and hydrology. Five radiocarbon dates from two of the cores provide sedimentation rate estimates ranging from 0.31 to 0.58 mm/year with an r2 of 0.97. Organic sedimentation was initiated in lakes in the Halifax area about 12 000 years ago. Low pollen densities and high proportions of herbaceous and shrub pollen types imply open country or tundra-like vegetational cover until ca. 10 000 B.P. A possible Allerød-type late-glacial climatic oscillation is apparent from the sediment and pollen records. Small birch pollen (cf. Betula nana), pine, spruce, willow, and ericaceous pollen dominate the late-glacial (ca. 12 000–10 000 B.P.) predominantly inorganic section of the sediment cores. It is presumed from the pollen data that hemlock (Tsuga canadensis) invaded the catchment areas about 8000 years ago, and that beech (Fagus grandifolia) arrived about 5000 years ago. Thermophilous Appalachian elements (Nyssa, Carya, Juglans, and Tilia) have never been part of postglacial Nova Scotian forests.

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