The ice core recovered from Prospector Russell Col on Mt Logan (5.4 km a.s.l.), in the Yukon spans over 20 000 years. This unique record offers a Pacific view of the stable isotope and chemical record from the Lateglacial to the present. The timescale is based on seasonal counted years, the largest known volcanic acid signatures and the major shift in stable isotopes and chemistry at the end of the Younger Dryas. There are large and sustained changes in the stable isotopic record that are anti-correlated with marine and continental chemistry series. The oxygen-18 in this area is not a proxy for palaeotemperature but rather for source region. The last major isotope shift in AD 1840 in δ( 18 O) and chemistry is compared with the Quinn's ENSO record. During periods of more frequent La Niña (stronger tropical easterlies) there is more zonal flow of water vapour transport to the Pacific Northwest, δ( 18 O) values are larger and the deuterium excess d smaller. These periods coincide with periods of lower accumulation/precipitation in southern Yukon. The Holocene δ( 18 O) record indicates many large shifts between the meridional (strong El Niño) and zonal (La Niña). Comparison of the Logan isotopic record and the moisture/temperature-sensitive time series of peat bog inception dates for the Northwest shows a strong correlation (0.36) that points to high accumulation rates coincident with low δ( 18 O) and enhanced meridional flow. Major changes in the core at 4200 BP and 7000-8000 BP point to enhanced meridional flow, which coincide with big changes in the Pacific palaeorecords of the balance between El Niño and La Niña. 4200 BP seems to have inaugurated the 'modern' ENSO world.
More than 130 new radiocarbon dates form the basis for 14 emergence curves for Prince of Wales and adjacent smaller islands. These curves and 14 additional curves from a large surrounding area are the primary basis for a set of central Arctic is abase maps. During and just after de glaciation the Boothia Arch was reactivated, producing 60-120 m of relief on the regionally elevated 9.3 ka shoreline. This deformation could have the form of a symmetrical ridge or a ridge with a fault zone on its western side. The ridge is flanked on the west by a large isobase plateau where the emerged 9.3 ka shoreline has little gradient. The 8 ka and younger shorelines are not affected by the Boothia Arch, but the Prince ofWales island isobase plateau persisted as the predominant regional isobasefeature throughout postglacial time. Since 8 ka all of Prince of Wales Island has emerged without de levelling of shorelines- a glacioisostatically abnormal pattern. We propose a Holocene block tectonics hypothesis: that postglacial rebound of the archipelago involved movement of a mosaic of blocks, some tilting, others not tilting. Small postglaciallineaments on eastern Prince ofWales Island may indicate that minor tectonism has continued until present. The emergence history of Prince ofWales I stand since 8 ka can be described by a single exponential least squares regression curve based entirely on 41 driftwood dates. Addition of two select shell dates produces a curve for the area of earliest de glaciation at about 11 ka. The curve has narrow 99% confidence limits, explains 94.72% of data variance, and has a correlation coefficient of0.97. The half-response time- the time during which one half of remaining emergence is accomplished- is 2000 years.
A surface of erosional planation, of regional extent in the central Canadian Arctic, was fragmented during the Eurekian Rifting Episode (Miocene-Pliocene) to produce the plateaus, plains, and lowlands of the study area and the rift valleys occupied by the large marine channels. Seven genetic groups of materials - rock, till, and glaciofluvial, glaciolacustrine, glaciomarine, marine, and fluvial sediments - constitute the surface of the map area, but rock and till are predominant. The till sheet exhibits major lateral facies changes which· define two large carbonate dispersal trains. Thick glaciomarine silt and clay extend in a wide belt across the southern part of the map area. Aspects of possible future engineering concern include: scarcity of sand and gravel in much of the area, natural instability of most unconsolidated material on slopes, high ground-ice content of thick till and fine grained glaciomarine sediment, annual thermal contraction and cracking of soil, frost heaving of soil and bedrock, ice push at sea and lake shores, and ice scouring of river beds and banks. Analyses of about 750 till samples provide the initial geochemical data base for this region. Variations in background levels of base metals reflect variations in carbonate content. All surface sediments shown on Map 1570A were deposited during the late Wisconsin glaciation. During the late Wisconsin maximum a major dome of the Laurentide Ice Sheet had a north-south oriented ice divide located over M'Clintock Channel. M'Clintock Dome was contiguous with the main body of the ice sheet to the south and coalesced with the Foxe Dome at the base of the Gulf of Boothia. M'Clintock Dome generated an eastward to east-northeastward flow over Boothia Peninsula and northern District of Keewatin. Important features of this flow regime were two large ice streams at the base of the ice sheet. Deglaciation began more than 9250 years ago and initial retreat was westward, towards the centre of the M'Clintock Dome. Retreat swung gradually to the south as a calving bay along the western side of Somerset Island and Boothia Peninsula penetrated the central parts of the dome. Boothia Peninsula was largely ice free by 8800 years B.P. and the marine-based part of the M'Clintock Dome had completely disappeared by 8700 years ago. A moraine system of regional extent in Arctic Canada, locally named the Chantrey Moraine System, was deposited shortly after 8700 years RP. and could reflect increased accumulation on the Laurentide Ice Sheet brought on by creation of a new moisture source when the sea invaded the region previously occupied by the northern part of the M'Clintock Dome. Emergence during deglaciation exceeded 30 m per century, at least in places, and averaged more than 53 cm per century during the last 4500 years.
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