Long-term nivation rates, Cathedral Massif, northwestern British Columbia

2020 ◽  
Vol 57 (11) ◽  
pp. 1305-1311 ◽  
Author(s):  
Kelsey E. Nyland ◽  
Frederick E. Nelson
Keyword(s):  
British Columbia ◽  
Contemporary Literature ◽  
Short Term ◽  
Denudation Rates ◽  
History Of ◽  
Aerial Vehicle ◽  
The Last Glacial Maximum ◽  
East West ◽  
The Last Glacial

Cryoplanation terraces (CTs) are large (3000–800 000 m2) erosional landforms found in upland periglacial environments. Two hypotheses for the formation of CTs are supported in contemporary literature: (1) CT formation is controlled primarily by geologic structure; and (2) CTs are climatically controlled through nivation, a suite of erosional processes associated with late-lying snowbanks. A persistent question in periglacial geomorphology is whether nivation can produce CT-scale landforms. This paper examines the unusual deglaciation history of “Frost Ridge” on the Cathedral Massif, northwestern British Columbia, to estimate long-term denudation attributable to nivation processes active since the last glacial maximum. Frost Ridge forms one flank of an east–west-oriented glacial valley. During deglaciation, marginal drainage created V-shaped erosional notches on both valley walls. Minimization of solar radiation on the steep north-facing wall (Frost Ridge) allowed snowbanks to accumulate and persist in the marginal drainage features and nivation processes to erode the slope. Today, several large nivation hollows (incipient CTs) are present near the summit of Frost Ridge, while the V-shaped marginal drainage features are preserved at lower elevations and on the opposite, south-facing valley wall. A high-resolution survey using an unmanned aerial vehicle (UAV) allowed volumes of marginal drainage and incipient terrace features to be compared. Based on this volumetric comparison, denudation rates are estimated to range from 4.2 to 125.8 mm/kyr, which are comparable with relatively short-term nivation rates reported from Antarctica and mid-latitude alpine periglacial areas.

Spatial variation of East Asian winter monsoon evolution between northern and southern China since the last glacial maximum

2021 ◽  
pp. 1-14
Author(s):  
Qin Li ◽  
Haibin Wu ◽  
Jun Cheng ◽  
Shuya Zhu ◽  
Chunxia Zhang ◽  
...  
Keyword(s):  
East Asian Winter Monsoon ◽  
Southern China ◽  
Ice Sheets ◽  
Northern China ◽  
Winter Monsoon ◽  
Asian Winter Monsoon ◽  
Spatial Differences ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract The East Asian winter monsoon (EAWM) is one of the most dynamic components of the global climate system. Although poorly understood, knowledge of long-term spatial differences in EAWM variability during the glacial–interglacial cycles is important for understanding the dynamic processes of the EAWM. We reconstructed the spatiotemporal characteristics of the EAWM since the last glacial maximum (LGM) using a comparison of proxy records and long-term transient simulations. A loess grain-size record from northern China (a sensitive EAWM proxy) and the sea surface temperature gradient of an EAWM index in sediments of the southern South China Sea were compared. The data–model comparison indicates pronounced spatial differences in EAWM evolution, with a weakened EAWM since the LGM in northern China but a strengthened EAWM from the LGM to the early Holocene, followed by a weakening trend, in southern China. The model results suggest that variations in the EAWM in northern China were driven mainly by changes in atmospheric carbon dioxide (CO2) concentration and Northern Hemisphere ice sheets, whereas orbital insolation and ice sheets were important drivers in southern China. We propose that the relative importance of insolation, ice sheets, and atmospheric CO2 for EAWM evolution varied spatially within East Asia.

scholarly journals Rheumatoid arthritis onset after COVID-19 infection: a case report

2021 ◽  
Vol 9 (12) ◽  
pp. 3713
Author(s):  
Thafar S. A. Safar ◽  
Karmen B. Katay ◽  
Reem H. Khamis
Keyword(s):  
Rheumatoid Arthritis ◽  
Case Report ◽  
Pathological Condition ◽  
Primary Health Care Centre ◽  
Short Term ◽  
Health Care Centre ◽  
Immune Mediated ◽  
Small Hand ◽  
History Of

At the end of 2019, coronavirus disease (COVID-19) outbreak is caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV2). Worldwide researchers and physician try to explore the mechanisms of damage induced by virus, they focus on the short-term and long-term immune-mediated consequences induced by the virus infection. Every day discover a new pathological condition induced by virus and new symptoms and disease may occur after recovery from disease. Our case report is 41 years old, Indian lady who presented to our primary health care centre complaining of multiple small hand joints pain, both elbows and knees pain with swelling of them and prolonged morning stiffness, diagnosed seropositive rheumatoid arthritis (RA) (arthritis, positive rheumatoid factor (RF), and X-ray changes) after 1 month recovery from COVID-19 infection. She did not have any joint pain and she had negative RF before COVID-19 infection with no family history of RA.

scholarly journals Journal of the History of Economic Thought Preprints - Limits to Arbitrage and Interest Rates: A Debate Between Keynes, Hawtrey and Hicks

2018 ◽  
Author(s):  
Lucy BRILLANT
Keyword(s):  
Business Cycle ◽  
Central Bank ◽  
Interest Rates ◽  
Economic Thought ◽  
History Of Economic Thought ◽  
Short Term ◽  
Limits To Arbitrage ◽  
History Of ◽  
The Business Cycle

This paper deals with a debate between Hawtrey, Hicks and Keynes concerning the capacity of the central bank to influence the short-term and the long-term rates of interest. Both Hawtrey and Keynes considered the central bank’s ability to influence short-term rates of interest. However, they do not put the same emphasis on the study of the long-term rates of interest. According to Keynes, long-term rates are influenced by future expected short-term rates (1930, 1936), whereas for Hawtrey (1932, 1937, 1938), long-term rates are more dependent on the business cycle. Short-term rates do not have much effect on long-term rates according to Hawtrey. In 1939, Hicks enters the controversy, giving credit to both Hawtrey’s and Keynes’s theories, and also introducing limits to the operations of arbitrage. He thus presented a nuanced view.

scholarly journals Mitochondrial Genome Diversity in the Central Siberian Plateau with Particular Reference to Prehistory of Northernmost Eurasia

2019 ◽  
Author(s):  
S. V. Dryomov ◽  
A. M. Nazhmidenova ◽  
E. B. Starikovskaya ◽  
S. A. Shalaurova ◽  
N. Rohland ◽  
...  
Keyword(s):  
Geographic Area ◽  
Mtdna Sequences ◽  
The Past ◽  
South Central ◽  
Sayan Region ◽  
History Of ◽  
Mitochondrial Genome Diversity ◽  
The Last Glacial Maximum ◽  
Complete Mtdna ◽  
The Last Glacial

AbstractThe Central Siberian Plateau was last geographic area in Eurasia to become habitable by modern humans after the Last Glacial Maximum (LGM). Through comprehensive mitochondrial DNA genomes retained in indigenous Siberian populations, the Ket, Tofalar, and Todzhi - we explored genetic links between the Yenisei-Sayan region and Northeast Eurasia over the last 10,000 years. Accordingly, we generated 218 new complete mtDNA sequences and placed them into compound phylogenies along with 7 newly obtained and 70 published ancient mt genomes. Our findings reflect the origins and expansion history of mtDNA lineages that evolved in South-Central Siberia, as well as multiple phases of connections between this region and distant parts of Eurasia. Our result illustrates the importance of jointly sampling modern and prehistoric specimens to fully measure the past genetic diversity and to reconstruct the process of peopling of the high latitudes of the Siberian subcontinent.

scholarly journals Morphology and late Cenozoic (<5 Ma) glacial history of the area between David and Mawson Glaciers, Victoria Land, Antarctica

1994 ◽  
Vol 20 ◽  
pp. 55-60
Author(s):  
Anja L.L.M. Verbers ◽  
Volkmar Damm
Keyword(s):  
Ice Sheet ◽  
Field Work ◽  
Topographic Map ◽  
Glacial History ◽  
Ice Surface ◽  
Victoria Land ◽  
Radio Echo Sounding ◽  
History Of ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Glacio-geological field work and radar ice-thickness sounding were carried out in the area between David and Mawson Glaciers. A subglacial topographic map has been compiled from radio-echo-sounding data. The northern part of this map shows that the trench of David Glacier reaches a depth of more than 1000 m below sea level. The area south of David Glacier comprises a landscape of nunatak clusters dissected by glaciated valleys with ice thicknesses as much as 800 m. Subglacial cirques occur at the outer margins of the nunatak clusters. A model for the regional glacial history is proposed. It starts with a major deglaciation in the Pliocene, which results in marine transgression in basins west of the Transantarctic Mountains. During the late Pliocene, the ice advanced towards the northeast, depositing a thin layer of (Sirius Group) till containing reworked mid-Pliocene marine diatoms. Due to accelerated mountain uplift, the ice cut iIlto the pre-Pliocene peneplain, eroding broad valleys. A period of ice-sheet retreat followed to expose a landscape of large nunataks separated by wide valleys. During this period, local cirque glaciation occurred. When the ice sheet advanced again, another phase of uplift forced the glaciers to cut deeper into the valleys. Probably since the Last Glacial Maximum the ice surface has lowered by about 100 m.

scholarly journals Long- to short-term denudation rates in the southern Apennines: geomorphological markers and chronological constraints

2011 ◽  
Vol 62 (1) ◽  
pp. 27-41 ◽  
Author(s):  
Dario Gioia ◽  
Claudio Martino ◽  
Marcello Schiattarella
Keyword(s):  
Sediment Accumulation ◽  
Radiometric Dating ◽  
Sedimentation Rates ◽  
Southern Apennines ◽  
Short Term ◽  
Small Catchment ◽  
Fluvial Terraces ◽  
Denudation Rates ◽  
Land Surfaces

Long- to short-term denudation rates in the southern Apennines: geomorphological markers and chronological constraints Age constraints of geomorphological markers and consequent estimates of long- to short-term denudation rates from southern Italy are given here. Geomorphic analysis of the valley of the Tanagro River combined with apatite fission track data and radiometric dating provided useful information on the ages and evolution of some significant morphotectonic markers such as regional planated landscapes, erosional land surfaces and fluvial terraces. Reconstruction of paleotopography and estimation of the eroded volumes were perfomed starting from the plano-altimetric distribution of several orders of erosional land surfaces surveyed in the study area. Additional data about denudation rates related to the recent and/or active geomorphological system have been obtained by estimating the amount of suspended sediment yield at the outlet of some catchments using empirical relationships based on the hierarchical arrangement of the drainage network. Denudation rates obtained through these methods have been compared with the sedimentation rates calculated for two adjacent basins (the Pantano di San Gregorio and the Vallo di Diano), on the basis of published tephrochronological constraints. These rates have also been compared with those calculated for the historical sediment accumulation in a small catchment located to the north of the study area, with long-term exhumation data from thermochronometry, and with uplift rates from the study area. Long- and short-term denudation rates are included between 0.1 and 0.2 mm/yr, in good agreement with regional data and long-term sedimentation rates from the Vallo di Diano and the Pantano di San Gregorio Magno basins. On the other hand, higher values of exhumation rates from thermochronometry suggest the existence of past erosional processes faster than the recent and present-day exogenic dismantling. Finally, the comparison between uplift and denudation rates indicates that the fluvial erosion did not match the tectonic uplift during the Quaternary in this sector of the chain. The axial zone of the southern Apennines should therefore be regarded as a landscape in conditions of geomorphological disequilibrium.

scholarly journals A brief history of climate – the northern seas from the Last Glacial Maximum to global warming

2014 ◽  
Vol 106 ◽  
pp. 225-246 ◽  
Author(s):  
Tor Eldevik ◽  
Bjørg Risebrobakken ◽  
Anne E. Bjune ◽  
Carin Andersson ◽  
H. John B. Birks ◽  
...  
Keyword(s):  
Global Warming ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Last Glacial ◽  
History Of ◽  
The Last Glacial Maximum ◽  
The Last Glacial

A new subspecies of Finlayson’s squirrel from an isolated island offshore of the Indochina Peninsula in southern Vietnam

Mammalia ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Duong Thuy Vu ◽  
Son Truong Nguyen ◽  
Masaharu Motokawa ◽  
Tu Ngoc Ly ◽  
Phuong Huy Dang ◽  
...  
Keyword(s):  
Gulf Of Thailand ◽  
Small Islands ◽  
Mitochondrial Cytochrome ◽  
Indochina Peninsula ◽  
New Subspecies ◽  
Southern Vietnam ◽  
History Of ◽  
The Gulf Of Thailand ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract We describe a new subspecies of Finlayson’s squirrel (Callosciurus finlaysonii) from Hon Nghe Island in the Gulf of Thailand. This island is located off the coast of southern Vietnam. In addition, we discussed the phylogenetic relationships among C. finlaysonii subspecies distributed on the isolated islands in the Gulf of Thailand. The new subspecies (C. finlaysonii honnghensis), which is endemic to Hon Nghe Island, differs from other C. finlaysonii subspecies in pelage colouration. The mitochondrial cytochrome b sequences showed that this squirrel is closely related to C. finlaysonii albivexilli and C. finlaysonii frandseni, which are endemic to the Koh Kut and Koh Chang islands, respectively, suggesting that the three subspecies diverged approximately 30,000 years ago. After the last glacial maximum, many small islands were formed by the sea level rise in the Gulf of Thailand, which was a consequence of global warming. Following the continuous fragmentation of the Sunda Continent, each C. finlaysonii subspecies could have evolved in each geographically isolated island in this gulf. Thus, studying C. finlaysonii subspecies may be used to track the recent geological history of the Gulf of Thailand.

5. Long Waves and Conjunctures of Democratization

2018 ◽  
pp. 67-81
Author(s):  
Dirk Berg-Schlosser
Keyword(s):  
Eighteenth Century ◽  
Long Waves ◽  
Political Equality ◽  
Short Term ◽  
Late Eighteenth Century ◽  
Long Wave ◽  
Late Eighteenth ◽  
The Future ◽  
History Of

This chapter focuses on the history of democratization since the late eighteenth century. It introduces the concepts of ‘waves’ (trends) and ‘conjunctures’ (briefer turmoils) and delineates the major developments in this respect. In this way, the major long-term and short-term factors leading to the emergence and breakdowns of democracies are also highlighted. The first long wave occurred during the period 1776–1914, followed by the first positive conjuncture in 1918–19, the second long wave (with some intermittent turbulences) in 1945–88, and the latest conjuncture in 1989–90. The chapter identifies the main ingredients to democratization throughout history, namely: republicanism, representation, and political equality. It concludes by considering some of the current perspectives and dangers for the future of democracy.

scholarly journals Fire Exclusion Destroys Habitats for At-Risk Species in a British Columbia Protected Area

Fire ◽  
2019 ◽  
Vol 2 (3) ◽  
pp. 48
Author(s):  
Kira M. Hoffman ◽  
Sara B. Wickham ◽  
William S. McInnes ◽  
Brian M. Starzomski
Keyword(s):  
British Columbia ◽  
Fire History ◽  
Prescribed Burning ◽  
Douglas Fir ◽  
Conifer Encroachment ◽  
Oak Trees ◽  
Composition And Structure ◽  
Fire Exclusion ◽  
History Of

Fire exclusion and suppression has altered the composition and structure of Garry oak and associated ecosystems in British Columbia. The absence of frequent low severity ground fires has been one of the main contributors to dense patches of non-native grasses, shrubs, and encroaching Douglas-fir trees in historical Garry oak dominated meadows. This case study uses remote sensing and dendrochronology to reconstruct the stand dynamics and long-term fire history of a Garry oak meadow situated within Helliwell Provincial Park located on Hornby Island, British Columbia. The Garry oak habitat in Helliwell Park has decreased by 50% since 1950 due to conifer encroachment. Lower densities and mortalities of Garry oak trees were associated with the presence of overstory Douglas-fir trees. To slow conifer encroachment into the remaining Garry oak meadows, we recommend that mechanical thinning of Douglas-fir be followed by a prescribed burning program. Reintroducing fire to Garry oak ecosystems can restore and maintain populations of plants, mammals, and insects that rely on these fire resilient habitats.

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