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Old Crow tephra found at the Palisades of the Yukon, Alaska
  • Old Crow tephra found at the Palisades of the Yukon, Alaska
  • This paper presents geochemical data that suggest a correlation between this newly discovered tephra and the Old Crow tephra, and provides the first chronologic constraints on the age of Pleistocene sediments at the Palisades of the Yukon.
Old Crow tephra: a new Late Pleistocene stratigraphic marker across north-central Alaska and western Yukon Territory
  • Old Crow tephra: a new Late Pleistocene stratigraphic marker across north-central Alaska and western Yukon Territory
  • Alaska ; Amérique du Nord ; Arctique ; Canada ; Etats-Unis ; Géographie des régions polaires ; Old Crow tephra ; Pléistocène supérieur ; Quaternaire zones froides ; Stratigraphie ; Téphrochronologie ; Volcanisme ; Yukon Territory
  • Old Crow tephra is the first extensive Pleistocene tephra unit to be documented in the northwestern part of North America. It has an age between the limits of 60,000 and 12,000 yr, set by C and fission-track measurements, respectively. Old Crow
  • tephra has been recognized in the Koyukuk Basin and Fairbanks region of Alaska, and in the Old Crow Lowlands of the northern Yukon Territory, some 600 km to the east-northeast. The source vent is unknown, but these occurrences, considered in relation
  • to the distant locations of potential Quaternary volcanic sources, demonstrate the widespread distribution of this tephra and underscore its importance as a regional stratigraphic marker.
Stratigraphic context of Old Crow tephra, Holitna lowland, interior southwest Alaska
  • Stratigraphic context of Old Crow tephra, Holitna lowland, interior southwest Alaska
  • The purpose of this paper is to document the stratigraphic and paleoenvironmental context of Old Crow tephra at the southwestern limit of its known distribution, thus contributing to interregional efforts to reconstruct Pleistocene paleoclimates
Thermoluminescence dating of the Pleistocene Old Crow tephra and adjacent loess, near Fairbanks, Alaska
  • Thermoluminescence dating of the Pleistocene Old Crow tephra and adjacent loess, near Fairbanks, Alaska
  • Utilisation de deux techniques différentes de thermoluminescence pour dater le tephra pléistocène Old Crow. Un dépôt a été daté directement à 110+- 16 ka pour ce tephra a été obtenu indirectement par l'analyse de grains du loess, immédiatement sus
Early and middle Wisconsinan environments of eastern Beringia : stratigraphic and paleo-ecological implications of the old crow tephra
  • Early and middle Wisconsinan environments of eastern Beringia : stratigraphic and paleo-ecological implications of the old crow tephra
  • Les données polliniques et macrofossiles de trois sites de Béringie orientale permettent de tracer un transect est-ouest des paléomilieux à l'époque du dépôt de l'Old Crow tephra.
New geomagnetic paleosecular-variation results from the Old Crow Basin, Yukon Territory, and their use in stratigraphic correlation
  • New geomagnetic paleosecular-variation results from the Old Crow Basin, Yukon Territory, and their use in stratigraphic correlation
  • susceptibilité magnétique, permet de déduire la position stratigraphique du tephra d'Old Crow, même s'il n'apparaît pas à cette localité| aussi elle atteste l'existence de variations paléoséculaires des signaux.
Dawson tephra : a prominent stratigraphic marker of Late Wisconsin age in west-central Yukon, Canada
  • Dawson tephra : a prominent stratigraphic marker of Late Wisconsin age in west-central Yukon, Canada
  • Le tephra de Dawson est le tephra le plus important des dépôts quaternaires des régions du Klondike et de Sixtymile au Yukon. Sa composition est très proche de celle du tephra bien connu de Old Crow et, comme ce dernier, indique une source de la
  • tephra au-dessus de l'Alaska et du Yukon.
Interglacial deposits at Birch Creek, northeast Interior Alaska
  • with which it may be correlated, in the light of the newly dated Old Crow Tephra.
Level of Lake Lahontan during deposition of the Trego Hot Springs tephra about 23,400 years ago
  • Level of Lake Lahontan during deposition of the Trego Hot Springs tephra about 23,400 years ago
  • ; Quaternaire zone chaude ; Trego Hot Spring tephra ; Téphrochronologie ; Téphrostratigraphie ; Zone subtropicale
  • The Trego Hot Springs tephra bed is a silicic tephra about 23,400 yr old, found at several localities in pluvial lake sediments in northern Nevada, southern Oregon, and northeastern California. It has been characterized petrographically
  • , by the major and minor element chemistry of its glass, and by its stratigraphic position with respect to other tephra layers. When the tephra fell, pluvial Lake Lahontan stood between 1256 and 1260 m, and that immediately thereafter the lake rose to at least
Correlation of Late Quaternary tephra Layers in a long pluvial sequence near Summer Lake, Oregon
  • Correlation of Late Quaternary tephra Layers in a long pluvial sequence near Summer Lake, Oregon
  • . Helens, Washington, at Crater Lake, Oregon, and in northwestern Nevada in the deposits of pluvial Lake Lahontan. These seven tephra beds are from 6800 to about 90,000 yr old. Extrapolation of these ages through assumption of constant depositional rate
  • Near Summer Lake in southern Oregon, 54 tephra beds of late Quaternary age are exposed in pluvial lake sediments of lake Chewaucan. Seven of the tephra beds near the top can be correlated with tephra deposits younger than 117,000 yr at Mount St
The age of Glacier Peak tephra in west-central Montana
  • The age of Glacier Peak tephra in west-central Montana
  • Mountains ; Sheep Mountain Bog ; Tardiglaciaire ; Tephra ; Tourbière ; Téphrochronologie
  • At Sheep Mountain Bog, near Missoula, Montana a late-glacial tephra, that probably fell in late summer, is preserved in lake deposits. Sediment surrunding the ash was 14C dated to about 11,200 yr B.P. Electron-microprobe analyses of the volcanic
  • glass and horublende phenocrysts from this ash layer indicate that they are similar in major-element chemistry to those of Glacier Peak layer G previously considered to be about 12,000 yr old or older.
Correlation of distal tephra layers in loess in the Channeled Scabland and Palouse of Washington State
  • Correlation of distal tephra layers in loess in the Channeled Scabland and Palouse of Washington State
  • layers that date late Quaternary and older giant floods in the Channeled Scabland allowing correlation of episode of floods among sites; and characterization of undated tephra layers in middle and early Quaternary loess sections important to the total
  • The AA. review the stratigraphy of the loess and buried soils and then develop three main themes : multiple correlations of tephra layers in late Quaternary loess, some from known and dated eruptions of cascade volcanoes; correlations of tephra
New geochemical evidence for the Youngest Toba Tuff in India
  • layer is not a correlative of older tephra erupted from Toba, as has been suggested on the basis of artifact assemblages.
  • New geochemical data on tephra samples from a layer present at several archeological sites in India support correlation of this layer to the Youungest Toba Tuff, erupted from northern Sumatra about 74,000 yr ago. The data show that the Indian tephra
Tephrochronology of Late Wisconsin deglaciation and Holocene glacier fluctuations near Glacier Peak, North Cascade Range, Washington
  • Tephra layers near Glacier Peak in the North Cascade Range provide limiting dates for four periods of alpine glacier advance. Field relations suggest that late Wisconsin alpine glaciers last advanced prior to the eruption of tephra layers from
  • Glacier Peak about 11.250 yr B.P. Late Wisconsin deglaciation in the central North Cascades was complete prior to the Glacier Peak tephra eruptions. Glaciers again expanded in the early Holocene about 8400-8300 yr B.P. Soil formed in alpine meadows during
  • an episode of mild climate in the middle Holocene prior to at least two intervals of glacier expansion: an older episode between 5100 and 3400 yr B.P., and a younger episode within the last 1000 yr.
Correlation of the Rockland ash bed, a 400,000-year-old stratigraphic marker in northern California and western Nevada, and implications for Middle Pleistocene paleogeography of central California
  • Correlation of the Rockland ash bed, a 400,000-year-old stratigraphic marker in northern California and western Nevada, and implications for Middle Pleistocene paleogeography of central California
  • Stratigraphic relations of the Rockland ash bed and older tephra layers in the Great Valley and near San Francisco suggest that the southern Great Valley emerged above sea level about 2 my ago, that its southerly outlet to the ocean was closed
Some effects of tephra falls on buildings in Tephra studies.
  • Some effects of tephra falls on buildings in Tephra studies.
Tephra studies and tephrochronology: a historical review with special reference to Iceland in Tephra studies.
  • Tephra studies and tephrochronology: a historical review with special reference to Iceland in Tephra studies.
About some widespread Late Pleistocene tephra horizons in Middle Europe
  • About some widespread Late Pleistocene tephra horizons in Middle Europe
  • Europe ; Géochimie ; Géographie de l'Europe ; Minéralogie ; Quaternaire ; Téphra ; Téphrochronologie ; Volcanisme
  • Des analyses par microsonde de minéraux mafiques de niveaux de téphras de Belgique, Allemagne et France ont conduit à la détermination de minéraux selon les classifications recommandées par l'IMA et confirment une corrélation antérieure de niveaux
  • de téphras. - (RS)
Chronostratigraphy of glaciations and permafrost episodes in the Cordillera of western North America
  • Glaciations in the Cordillera of western North America began during the Late Miocene in the St Elias Range and coastal ranges near Anchorage, Alaska. Radiometric dating of the tephra and lava flows intercalated in the succession of older tills
Approximate dating of tephra in Tephra studies.
  • Approximate dating of tephra in Tephra studies.
  • Two methods that look promising are tephra-hydration dating, and etching of heavy mineral phenocrysts. Basic research into the weathering of tephra will be needed before either method can be used with confidence, but the potential