41 research outputs found
Pollen Diagrams in the Mackenzie Delta Area, N.W.T.
Considers postglacial climatic changes in northern Mackenzie District, from palynological and other evidence. Peat from exposures in two areas, also alluvial sediments from a drill hole were analyzed; pollen diagrams with radiocarbon control are presented for the peat. From these investigations and geomorphic interpretation of the exposures, fossil evidence, etc., a tentative climatic sequence is proposed; deglaciation about 12,000 yrs ago, a cool-dry climate 8500-7500 B.P., a warmer and drier period, and increased moisture and cooling climate in late postglacial time. The last changes are indicated by increases in alder and Ericaceae and formation of pingos
SIPRE Ice-Corer for Obtaining Samples from Permanently Frozen Bogs
Discusses the effectiveness of sampling devices demonstrated by summer 1962 field use in northern Yukon and laboratory tests in Mar. 1963. Hand drilling in Yukon Territory produced excellent cores, but the cutting teeth in the ice-corer were quickly dulled from mineral matter; holes 7-8 ft deep required three hrs drilling. Tests with power drives indicated that a two-man team could core a frozen bog 8 ft deep in 30-45 min. The two types of power units tested: a McCulloch chainsaw motor, and a Haynes earth drill, were both adequate; details are given
A Study of Late-Quaternary Plant-Bearing Beds in North-Central Baffin Island, Canada
Plant-bearing beds, exposed by downcutting of the Isortoq River at the northern end of the Barnes Icecap, have been folded, apparently by east-west moving overriding ice, truncated and overlain by horizontal alluvial sediments. Radiocarbon dates for plant material from the Isortoq River (folded unit), Flitaway Lake, and Lewis Glacier localities are >30,000 to >40,000 yr BP, from the horizontal beds, 14,000 ± 400 yr BP. The vegetation was probably similar to that of southern Baffin Island today; the Isortoq beds are assigned to the Sangamon interglacial. Pollen diagrams and description of the present vegetation and climate are included.Étude des dépôts végétaux fini-quaternaires dans le centre-nord de l'île de Baffin, Canada. On a daté à plus de 38,830 et 40,000 ans av. p. respectivement des horizons végétaux enfouis le long de la rivière Isortoq, à l'extrémité nord de la calotte de Barnes, sur l'île de Baffin. Des études palynologique et paléobotanique indiquent la présence d'espèces (comme le bouleau nain) qui se retrouvent aujourd'hui à plusieurs centaines de kilomètres au sud de cette localité. En déduisant des conditions climatiques plus favorables qu'à présent, on assigne à ces horizons un âge interglaciaire (Sangamon). Le plissement des horizons par de la glace de recouvrement et l'orientation de ces plis indiquent que l'accumulation d'une calotte initiale s'est produite à l'est de la localité
Temperatures at the last interglacial simulated by a coupled ocean-atmosphere climate model
Possible late Pleistocene uplift, Chesapeake Bay entrance
Paleontological and lithological studies of engineering borings and boring logs subaerial erosion surface of Pliocene (?)-Pleistocene age cuts across clastic sediments of pre-Yorktownian Miocene age in the subsurface and subbottom of the lower Chesapeake Bay area. When the bore-hole data are coupled with the results of subbottom echo profiling and piledriving records, it is possible to construct accurate cross sections of the buried Miocene-Pleistocene contact. The cross sections show lows in the erosion surface that may be correlated with the buried channels of the Pleistocene Elizabeth, James, York, and Susquehanna river valleys. Probable channel depths below mean low water at control points are: 100 feet (Elizabeth River, beneath Tunnel no. 1), 155 feet (James River, at Hampton Roads Tunnel), 120 feet (York River, at Yorktown), 158 feet (Susquehanna River, off Cape Charles City), and 160 feet (Susquehanna River, at Fisherman Island, Cape Charles). The channel depths of what is believed to be the buried Susquehanna River valley are less than expected when placed on a curve showing the expectable gradients of that stream during the time of the most-recent, maximum lowering of sea level (ca. 18,000 years B.P.). The discrepancy suggests uplift of that channel of approximately 170 feet in about the last 18,000 years