Late Wisconsinan glacitectonic structures and evidence of postglacial permafrost in north-central Newfoundland

1977 ◽  
Vol 14 (12) ◽  
pp. 2797-2806 ◽  
Author(s):  
N. Eyles
Keyword(s):  
High Rate ◽  
The West ◽  
North Central ◽  
Deformation Structures ◽  
Pollen Zone ◽  
Air Temperatures ◽  
Ground Collapse ◽  
Glacier Ice ◽  
Ice Wedge ◽  
Late Wisconsinan

Rhythmically-bedded glaciofluvial sediments deposited subaqueously and now exposed on an emerged coastal foreland in north-central Newfoundland, exhibit postdepositional deformation structures such as synclinal folds and faulted zones of ground collapse, the result of melting of underlying buried glacier ice. A high rate of glaciofluvial deposition is indicated. The development of fault systems in those sediments overlying decaying glacier ice can be compared with laboratory simulations of vertical foundering in sedimentary rocks. Ice-wedge casts transecting folded and faulted sections in the area are indisputable evidence of subsequent permafrost conditions, i.e. a period when mean annual air temperatures lay below −6 °C. A rise of at least 10.4 °C in mean annual air temperature is indicated since that time. A severe periglacial climate is considered to have existed in the area from 12 000 to 10 000 years BP and ice wedges developed with a minimum growth rate of 1.25 mm/year. Comparison with reports of ice-wedge casts in Nova Scotia and the west coast of Newfoundland indicate that the period which they formed in north-central Newfoundland may be correlated with the tundra pollen zone L-3 of Livingstone and Livingstone, the Greatlakian substage of the Lake Wisconsinan in Midcontinental North America.

The Drift des Demoiselles on the Magdalen Islands (Québec, Canada): sedimentological and micromorphological evidence of a Late Wisconsinan glacial diamict

2013 ◽  
Vol 50 (5) ◽  
pp. 545-563 ◽  
Author(s):  
Audrey M. Rémillard ◽  
Bernard Hétu ◽  
Pascal Bernatchez ◽  
Pascal Bertran
Keyword(s):  
Sea Level ◽  
Ice Flow ◽  
Glacial Deposit ◽  
Marine Transgression ◽  
Deformation Structures ◽  
Ice Cap ◽  
Ice Wedge ◽  
Late Wisconsinan ◽  
Different Origin ◽  
Magdalen Islands

The deposits identified as being the Drift des Demoiselles, which is the upper unit of the southern Magdalen Islands (Québec, Canada), belong to two units of different origin, glacial and glaciomarine. At Anse à la Cabane, the glacial deposit comprises two subunits: a glacitectonite at the base and a subglacial traction till at the top. Numerous glaciotectonic deformation structures suggest ice flow towards the southeast. The till is above an organic horizon dated to ∼47–50 ka BP. New data presented here show that the southern part of the Magdalen archipelago was glaciated during the Late Wisconsinan. We relate this ice flow to the Escuminac ice cap, whose centre of dispersion was located in the Gulf of St. Lawrence, northwest of the islands. At Anse au Plâtre, the top of the Drift des Demoiselles is a glaciomarine deposit. At Anse à la Cabane, the till is covered by a stratified subtidal unit located at ∼20 m above sea level. Both were deposited during the marine transgression that followed deglaciation. At Anse à la Cabane, three ice-wedge casts truncate the till and the subtidal unit, providing evidence that periglacial conditions occurred on the archipelago after deglaciation.

Late Wisconsinan Ice-Wedge Polygons near Kitchener, Ontario, Canada

1972 ◽  
Vol 9 (6) ◽  
pp. 607-617 ◽  
Author(s):  
Alan V. Morgan
Keyword(s):  
Aerial Photographs ◽  
Air Temperatures ◽  
Ice Wedge ◽  
Late Wisconsinan ◽  
Sand And Gravel

Reconnaissance from a light aircraft has revealed areas of polygonal ground east of Kitchener, Ontario. Examination of aerial photographs of the same region has shown additional polygons all developed upon Port Stanley II Till. Trenching of a polygon has exposed wedge-shaped sand and gravel infilled structures interpreted as ice-wedge casts. The wedges are believed to have been active prior to 13 000 years B.P., probably under tundra conditions, with mean annual air temperatures some 25 °F (13–14 °C) cooler than present.

PRE-BONNEVILLE LAKES IN CACHE VALLEY AND EXCAVATION OF CUTLER NARROWS ACROSS THE CACHE BUTTE DIVIDE IN THE WEST, NORTH-CENTRAL UTAH AND SOUTHEASTERN IDAHO

2020 ◽  
Author(s):  
Robert Q. Oaks ◽  
◽  
Susanne U. Janecke ◽  
Tammy M. Rittenour ◽  
Thad L. Erickson ◽  
...  
Keyword(s):  
The West ◽  
North Central ◽  
Cache Valley ◽  
West North Central

Abstract MP75: Geographic Variation in Stroke Rates and Oral Anticoagulation Use among Medicare Beneficiaries with Atrial Fibrillation

Circulation ◽  
2018 ◽  
Vol 137 (suppl_1) ◽  
Author(s):  
Inmaculada Hernandez ◽  
Samir Saba ◽  
Yuting Zhang
Keyword(s):  
Atrial Fibrillation ◽  
Ischemic Stroke ◽  
Geographic Variation ◽  
Newly Diagnosed ◽  
Medicare Beneficiaries ◽  
The West ◽  
North Central ◽  
Census Division ◽  
Adjusted Rate ◽  
West North Central

Background: Recent studies have shown strong geographic variation in oral anticoagulation (OAC) use in atrial fibrillation (AF); however, it remains unknown how this contributes to the geographic variation in ischemic stroke observed across the US. The objective of the present study was to evaluate the relationship between the geographic variation in the initiation of OAC and the incidence of ischemic stroke in a cohort of Medicare beneficiaries newly diagnosed with AF. Methods: Using 2013-2014 claims data from a 5% random sample of Medicare beneficiaries, we identified patients newly diagnosed with AF in 2013-2014 and categorized them according to their initiation of OAC. Our sample included 21,226 OAC initiators and 20,068 patients who did not initiate OAC therapy. We assigned each patient to one of the 9 US Census Divisions using the zip code, and collected their medical claims with a diagnosis of ischemic stroke. We constructed logistic regression models to estimate the average adjusted probability of OAC initiation and Poisson models to estimate the average adjusted rate of ischemic stroke, in each Census Division. Both estimates were adjusted for demographics, eligibility for Medicaid coverage and for low-income subsidy, enrollment in a Medicare Advantage Part D plan, and a comprehensive list of clinical characteristics. We computed the correlation between the average adjusted probability of OAC initiation and the average adjusted rate of ischemic stroke at the Census Division level. Results: The probability of OAC initiation was lowest in the West South Central (0.47) and highest in the West North Central (0.54) and New England (0.54). The average adjusted rate of ischemic stroke was lowest in the West North Central (0.09) and highest in the South Atlantic (0.14) and South West Central (0.14). The average adjusted probability of OAC initiation at the Census Division level and the average adjusted rate of ischemic stroke were inversely correlated, with R=-0.576, p-value=0.10. This suggests that variation in OAC initiation likely explains at least a third of geographic variation in ischemic stroke [R 2 =(-0.576) 2 =0.332]. Conclusions: Our results suggest that geographic variations in OAC initiation within the U.S. explain, in part, variations in the incidence of ischemic stroke among AF patients. Further mechanistic research using advanced causal mediation models is warranted.

PUBLIC HEALTH, NURSING AND MEDICAL SOCIAL WORK

PEDIATRICS ◽  
1948 ◽  
Vol 2 (1) ◽  
pp. 138-140
Keyword(s):  
Public Health ◽  
South Carolina ◽  
New England ◽  
The West ◽  
Central Section ◽  
North Central ◽  
South Central ◽  
High Incidence ◽  
Health Nursing ◽  
West North Central

THE accompanying table summarizes the incidence of nine important communicable diseases, based on weekly telegraphic reports from State health departments. The reports from each State for each week are published in PUBLIC HEALTH REPORTS under the section "Incidence of Disease." [See Table in Source Pdf]. Diseases Above Median Incidence Measles—The number of cases of measles rose from 102,680 during the preceding 4 weeks to 114,983 during the 4 weeks ended May 22. The incidence was 3.4 times the number of cases reported for the corresponding period in 1947, which was, however, a comparatively low measles year, but it was only about 10 percent above the 1943-47 median. In the New England and East South Central sections the incidence was below the normal expectancy and in the South Atlantic section the number of cases was only slightly higher than the median for the preceding 5 years, but in the other 6 sections the increases over the median expectancy ranged from 1.1 times the median in the West North Central section to 3.4 times the median in the West South Central section. Poliomyelitis.— The number of cases of poliomyelitis rose from 126 during the preceding 4-week period to 440 during the current 4 weeks. The incidence was 3.5 times that reported for these weeks in 1947, which number (126 cases) also represents the 1943-47 median. An increase of this disease is expected at this season of the year, but the current number of cases represents a larger increase at this time than has normally occurred in preceding years. While each section of the country except New England contributed to the relatively high incidence, the greatest excesses over the 5-year medians were reported from the West North Central and West South Central sections. Of the total cases Texas reported 179, California 62, South Carolina 46, New Jersey 16, Iowa 14, Florida 12, Alabama 11, and Illinois, South Dakota, and Louisiana 10 each; 85 percent of the reported cases occurred in those 10 states which represent every section of the country except the New England and Mountain sections. Since the beginning of the year there have been 947 cases of poliomyelitis reported as compared with 894 and 810 for the corresponding period in 1947 and 1946, respectively.

scholarly journals Microtopographic control on the ground thermal regime in ice wedge polygons

2018 ◽  
Vol 12 (6) ◽  
pp. 1957-1968 ◽  
Author(s):  
Charles J. Abolt ◽  
Michael H. Young ◽  
Adam L. Atchley ◽  
Dylan R. Harp
Keyword(s):  
Thermal Conditions ◽  
Ground Temperature ◽  
The Arctic ◽  
Near Surface ◽  
Hydrologic Processes ◽  
Ground Temperatures ◽  
Air Temperatures ◽  
Winter Temperatures ◽  
Ice Wedge ◽  
Prudhoe Bay

Abstract. The goal of this research is to constrain the influence of ice wedge polygon microtopography on near-surface ground temperatures. Ice wedge polygon microtopography is prone to rapid deformation in a changing climate, and cracking in the ice wedge depends on thermal conditions at the top of the permafrost; therefore, feedbacks between microtopography and ground temperature can shed light on the potential for future ice wedge cracking in the Arctic. We first report on a year of sub-daily ground temperature observations at 5 depths and 9 locations throughout a cluster of low-centered polygons near Prudhoe Bay, Alaska, and demonstrate that the rims become the coldest zone of the polygon during winter, due to thinner snowpack. We then calibrate a polygon-scale numerical model of coupled thermal and hydrologic processes against this dataset, achieving an RMSE of less than 1.1 ∘C between observed and simulated ground temperature. Finally, we conduct a sensitivity analysis of the model by systematically manipulating the height of the rims and the depth of the troughs and tracking the effects on ice wedge temperature. The results indicate that winter temperatures in the ice wedge are sensitive to both rim height and trough depth, but more sensitive to rim height. Rims act as preferential outlets of subsurface heat; increasing rim size decreases winter temperatures in the ice wedge. Deeper troughs lead to increased snow entrapment, promoting insulation of the ice wedge. The potential for ice wedge cracking is therefore reduced if rims are destroyed or if troughs subside, due to warmer conditions in the ice wedge. These findings can help explain the origins of secondary ice wedges in modern and ancient polygons. The findings also imply that the potential for re-establishing rims in modern thermokarst-affected terrain will be limited by reduced cracking activity in the ice wedges, even if regional air temperatures stabilize.

Periglacial Features Indicative of Permafrost: Ice and Soil Wedges

1976 ◽  
Vol 6 (1) ◽  
pp. 3-26 ◽  
Author(s):  
Robert F. Black
Keyword(s):  
The United States ◽  
Pressure Effects ◽  
Freezing And Thawing ◽  
Wetting And Drying ◽  
Ice Wedge ◽  
Surface Patterns ◽  
Late Wisconsinan ◽  
Collapse Structures ◽  
Similar Soil ◽  
Permafrost Regions

Ice wedges are wedge-shaped masses of ice, oriented vertically with their apices downward, a few millimeters to many meters wide at the top, and generally less than 10 m vertically. Ice wedges grow in and are confined to humid permafrost regions. Snow, hoar frost, or freezing water partly fill winter contraction cracks outlining polygons, commonly 5–20 m in diameter, on the surface of the ground. Moisture comes from the atmosphere. Increments of ice, generally 0.1–2.0 mm, are added annually to wedges which squeeze enclosing permafrost aside and to the surface to produce striking surface patterns. Soil wedges are not confined to permafrost. One type, sand wedges, now grows in arid permafrost regions. Sand wedges are similar in dimensions, patterns, and growth rates to ice wedges. Drifting sand enters winter contraction cracks instead of ice. Fossil ice and sand wedges are the most diagnostic and widespread indicators of former permafrost, but identification is difficult. Any single wedge is untrustworthy. Evidence of fossil ice wedges includes: wedge forms with collapse structures from replacement of ice; polygonal patterns with dimensions comparable to active forms having similar coefficients of thermal expansion; fabrics in the host showing pressure effects; secondary deposits and fabric indicative of a permafrost table; and other evidence of former permafrost. Sand wedges lack open-wedge, collapse structures, but have complex, nearly vertical, crisscrossing narrow dikelets and fabric. Similar soil wedges are produced by wetting and drying, freezing and thawing, solution, faulting, and other mechanisms. Many forms are multigenetic. Many socalled ice-wedge casts are misidentified, and hence, permafrost along the late-Wisconsinan border in the United States was less extensive than has been proposed.

Latest Devonian–Earliest Mississippian nearshore trace-fossil assemblages from West Virginia, Pennsylvania, and Maryland

1987 ◽  
Vol 61 (5) ◽  
pp. 865-889 ◽  
Author(s):  
Thomas W. Bjerstedt
Keyword(s):  
West Virginia ◽  
Trace Fossils ◽  
Price Formation ◽  
Late Devonian ◽  
Tidal Channel ◽  
Fair Weather ◽  
The West ◽  
North Central ◽  
The North ◽  
Channel Systems

Trace fossils are used in deposystem analysis of Late Devonian–Early Mississippian nearshore facies in the north-central Appalachian Basin. These nearshore facies resulted from separate transgressions during latest Devonian (Cleveland Shale) and earliest Mississippian (Sunbury Shale) time. Emphasis is placed on a well-exposed section at Rowlesburg, West Virginia, where the Oswayo, Cussewago Sandstone, and Riddlesburg Shale Members of the Price Formation are exposed.The Oswayo Member at Rowlesburg preserves an offshore-to-lower shoreface transition in a complex of euryhaline, protected-bay, lagoon, and possible estuarine facies. Cruziana is common and occurs along with Arthrophycus, Bifungites, Chondrites, Planolites, Palaeophycus, Rhizocorallium, Rosselia, Rusophycus, and Skolithos in intensely bioturbated mudstone, siltstone, and sandstone. These lithologies were deposited below fair-weather wave base and grade upsection to upper shoreface facies comprised of thick, horizontally-laminated sandstones with thinner, burrowed mudstone interbeds. Upper shoreface traces consist of Arenicolites, Cruziana, Diplocraterion, Dimorphichnus, Planolites, Thalassinoides, and Skolithos. Skolithos “pipe rock” sandstones occur at the toe of upper shoreface facies. Eastward the Oswayo Member grades into a restricted-bay facies and finally into beach and tidal flat facies near its stratigraphic wedge-out in eastern West Virginia and western Maryland. The Cussewago Sandstone Member at Rowlesburg overlies the Oswayo and is bounded at the top by a disconformity. The Cussewago contains Arenicolites, Isopodichnus, Phycodes, Planolites, and Skolithos in upper shoreface sandstones possibly related to deposition in deltaic or tidal channel systems.Regionally, the Riddlesburg Shale records a range of euryhaline environments in shallow-shelf, open-bay, and probable estuarine facies. The Riddlesburg Shale Member at Rowlesburg is comprised of dark-grey silty shales, siltstones, and hummocky cross-stratified sandstones. Trace fossils include Bergaueria, Bifungites, Fustiglyphus?, Helminthopsis, Planolites, and Skolithos. Lithofacies of the Riddlesburg Shale in West Virginia were markedly influenced by a syndepositionally active basement feature, the West Virginia Dome. Riddlesburg-age shoreface sandstones deposited on the crest of the Dome contain apparent omission surfaces with common Rhizocorallium and Arenicolites, Cruziana?, Planolites, and Skolithos.

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