scholarly journals Glacial and Subglacial Topography of West Antarctica

1961 ◽  
Vol 3 (29) ◽  
pp. 882-911 ◽  
Author(s):  
Charles R. Bentley ◽  
Ned A. Ostenso
Keyword(s):  
Sea Level ◽  
Open Water ◽  
West Antarctica ◽  
Ice Flow ◽  
North West ◽  
Mountainous Regions ◽  
The North ◽  
Subglacial Topography ◽  
Rock Interface ◽  
Altimetric Measurements

AbstractA summary of the techniques used and results obtained from three oversnow traverses in Marie Byrd Land and the Ellsworth Highland between January 1957 and January 1959 is presented. Seismic reflection shooting at 30 nautical mile (55.5 km.) intervals was combined with gravity, magnetic and altimetric measurements to determine the glacial and subglacial topography. It was found that a vast portion of West Antarctica has an ice–rock interface well below sea-level. A major connecting channel with a maximum depth of more than 2,500 m. below sea-level exists between the Ross and Bellingshausen–Amundsen Seas, whereas there is no major topographic connection between the Ross and Weddell Seas. This channel divides West Antarctica into two provinces with granite and rocks of sedimentary origin to the east and south, and a volcanic region to the north-west. Present ice flow is outward from two high areas, centred over mountainous regions on either side of the channel. It is concluded that the present ice sheet has grown from the convergence of the two smaller ice sheets which formed in the mountainous areas and joined across the intervening open water.

scholarly journals Glacial and Subglacial Topography of West Antarctica

1961 ◽  
Vol 3 (29) ◽  
pp. 882-911 ◽  
Author(s):  
Charles R. Bentley ◽  
Ned A. Ostenso
Keyword(s):  
Sea Level ◽  
Open Water ◽  
West Antarctica ◽  
Ice Flow ◽  
North West ◽  
Mountainous Regions ◽  
The North ◽  
Subglacial Topography ◽  
Rock Interface ◽  
Altimetric Measurements

Abstract A summary of the techniques used and results obtained from three oversnow traverses in Marie Byrd Land and the Ellsworth Highland between January 1957 and January 1959 is presented. Seismic reflection shooting at 30 nautical mile (55.5 km.) intervals was combined with gravity, magnetic and altimetric measurements to determine the glacial and subglacial topography. It was found that a vast portion of West Antarctica has an ice–rock interface well below sea-level. A major connecting channel with a maximum depth of more than 2,500 m. below sea-level exists between the Ross and Bellingshausen–Amundsen Seas, whereas there is no major topographic connection between the Ross and Weddell Seas. This channel divides West Antarctica into two provinces with granite and rocks of sedimentary origin to the east and south, and a volcanic region to the north-west. Present ice flow is outward from two high areas, centred over mountainous regions on either side of the channel. It is concluded that the present ice sheet has grown from the convergence of the two smaller ice sheets which formed in the mountainous areas and joined across the intervening open water.

scholarly journals The impact of sea-level rise on tidal characteristics around Australia

Ocean Science ◽  
2019 ◽  
Vol 15 (1) ◽  
pp. 147-159 ◽  
Author(s):  
Alexander Harker ◽  
J. A. Mattias Green ◽  
Michael Schindelegger ◽  
Sophie-Berenice Wilmes
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Open Boundary ◽  
Open Boundary Conditions ◽  
Tidal Dissipation ◽  
North West ◽  
The North ◽  
Tidal Changes ◽  
Tidal Characteristics ◽  
The Impact

Abstract. An established tidal model, validated for present-day conditions, is used to investigate the effect of large levels of sea-level rise (SLR) on tidal characteristics around Australasia. SLR is implemented through a uniform depth increase across the model domain, with a comparison between the implementation of coastal defences or allowing low-lying land to flood. The complex spatial response of the semi-diurnal M2 constituent does not appear to be linear with the imposed SLR. The most predominant features of this response are the generation of new amphidromic systems within the Gulf of Carpentaria and large-amplitude changes in the Arafura Sea, to the north of Australia, and within embayments along Australia's north-west coast. Dissipation from M2 notably decreases along north-west Australia but is enhanced around New Zealand and the island chains to the north. The diurnal constituent, K1, is found to decrease in amplitude in the Gulf of Carpentaria when flooding is allowed. Coastal flooding has a profound impact on the response of tidal amplitudes to SLR by creating local regions of increased tidal dissipation and altering the coastal topography. Our results also highlight the necessity for regional models to use correct open boundary conditions reflecting the global tidal changes in response to SLR.

A fission track thermochronological study of King George and Livingston islands, South Shetland Islands (West Antarctica)

2004 ◽  
Vol 16 (2) ◽  
pp. 191-197 ◽  
Author(s):  
I. SELL ◽  
G. POUPEAU ◽  
J.M. GONZÁLEZ-CASADO ◽  
J. LÓPEZ-MARTÍNEZ
Keyword(s):  
South Shetland Islands ◽  
West Antarctica ◽  
The South ◽  
North West ◽  
The North ◽  
Early Oligocene ◽  
Barton Peninsula ◽  
Bransfield Basin ◽  
Back Arc ◽  
The Antarctic

This paper reports the dating of apatite fission tracks in eleven rock samples from the South Shetland Archipelago, an island arc located to the north-west of the Antarctic Peninsula. Apatites from Livingston Island were dated as belonging to the Oligocene (25.8 Ma: metasediments, Miers Bluff Formation, Hurd Peninsula) through to the Miocene (18.8 Ma: tonalites, Barnard Point). Those from King George Island were slightly older, belonging to the Early Oligocene (32.5 Ma: granodiorites, Barton Peninsula). Towards the back-arc basin (Bransfield Basin), the apatite appears to be younger. This allows an opening rate of approximately 1.1 km Ma−1 (during the Miocene–Oligocene interval) to be calculated for Bransfield Basin. Optimization of the apatite data suggests cooling to 100 ± 10°C was coeval with the end of the main magmatic event in the South Shetland Arc (Oligocene), and indicates slightly different tectonic-exhumation histories for the different tectonic blocks.

The Excavation of Nympsfield Long Barrow, Gloucestershire

1938 ◽  
Vol 4 (1) ◽  
pp. 188-213 ◽  
Author(s):  
Elsie M. Clifford
Keyword(s):  
Sea Level ◽  
Rural District ◽  
North West ◽  
The North

The Nympsfield long barrow is situated in the parish of Frocester, but is less than a mile to the north-west of Nympsfield village. The boundaries of the Parish, the Rural District and the Union, run from north to south down the centre of the field, called ‘Buckholt End,’ in which it lies. The position of the barrow is latitude 51° 42′ 35″ and longitude 2° 17′ 54″ (six-inch O.S., Gloucs. XLIX S.W.) and its height 750 feet above sea level. Ninety yards to the east of the barrow there is a road, marked by Grundy as a ‘ridgeway,’ which now runs from Selsley Hill to Uley (fig. 1). The underlying rock is the Inferior Oolite, a formation separable into numerous sub-divisions, here including, in descending order, Clypeus Grit, Upper Trigonia Grit and Upper Freestone. The greater part of the barrow, if not the whole of it rests on Clypeus Grit.

Ritual Inscriptions from Uzundara

2021 ◽  
pp. 250
Author(s):  
Nigora D. Dvurechenskaya
Keyword(s):  
Sea Level ◽  
Natural Boundary ◽  
Crucial Point ◽  
North West ◽  
The North ◽  
Archaeological Materials

The paper presents three Greek votive graffiti from the excavations of citadel of Fortress Uzundara (Uzbekistan) and describes their archaeological context. This fortress is located on the North-West Border of Ancient Bactria, and represents the crucial point in the tens–kilometers long borderline fortification system in this area. It is built at altitude of 1700 meters above the sea level. The fortress stands on the narrow (220 meters) neck between the precipitous walls of the natural boundary Kara-Kamar and the canyon Uzundara, and locks the pass for the equestrian troops intent to bypass the borderline wall of Darband in 7 kilometers northward. It consists of the principal rhomboid castle, a detached and adjacent triangular citadel, same sections of the external walls, and of three external towers. The main goal of this fortress was the warning of the sudden attack of nomads from the Karshin steppes. A military garrison was stationed in the Uzundara fortress – a Seleucid frurion in the first quarter of the 3rd century BC. Apparently at this time it consisted of Macedonians and Greeks. This is clearly evidenced by archaeological materials, including epigraphic ones. We analyze three artefacts voted to Demeter of the Mountains and the Borderline, Zeus–Mitra, and Zoroastrian Deity Srosh. The most complete inscription – votive to Demeter – persists on the three fragments of tagora (luterium) which could be used for the ritual ablution. They were founded in different years and in different places around the ovoid cellar on the rocky complex of the citadel Uzundara.

scholarly journals I.—The Kishon and Jordan Valleys

1904 ◽  
Vol 1 (12) ◽  
pp. 575-582 ◽  
Author(s):  
T. G. Bonney
Keyword(s):  
Sea Level ◽  
Difficult Problem ◽  
The South ◽  
North West ◽  
The North ◽  
South West ◽  
Western Side ◽  
Physical Geology

That broad trench through the Palestine Highlands, an ancient highway and battlefield of nations—the plain of Esdraelon or the valley of Megiddo, together with the plain of Acre—has for long presented to me a difficult problem in Physical Geology, for it seemed inexplicable by subaerial denudation under existing conditions. Its floor varies roughly from five to eight miles in breadth; running approximately from south-east to north-west, it is bounded on the more western side by the limestone mountains of Samaria and on the more eastern by those of Galilee. The former descend from the ridge of Carmel (1,742 feet at highest) with a fairly steep escarpment, which becomes a little less regular as we follow it to the bastion-mass of Mount Gilboa; the latter correspond in their general outlines with those of the eastern portion of Samaria, but the advance of a lower spur towards the south-west divides the plain of Esdraelon from that of Acre, by a kind of strait in which, so far as I could see, there is but little level ground on either side of the Kishon. This spur, however, of the northern hills, hardly does more than interrupt the floor of the Kishon valley, for above it the great trench is continued between two hill masses, much of these ranging from thirteen to sixteen hundred feet above sea-level. Beyond the strait the upper basin (plain of Esdraelon) quickly broadens out, extending towards the south-east for about fifteen or sixteen miles, where it is divided into two arms by Jebel Duhy (Little Hermon) (1,690 feet), which is thus isolated from Tabor (1,846 feet) on the north, and from Gilboa (1,698 feet) on the south; a broad, rather shallow, grassy valley descending from the last-named mass to lose itself in the plain.

Further Discoveries of Flint Implements in the Brown Boulder Clay of North-West Norfolk

1932 ◽  
Vol 6 (4) ◽  
pp. 306-315 ◽  
Author(s):  
J. Reid Moir
Keyword(s):  
Sea Level ◽  
Geological Survey ◽  
Prehistoric Archaeology ◽  
East Anglia ◽  
North West ◽  
Terminal Moraine ◽  
The North ◽  
Boulder Clay ◽  
Western Portion ◽  
North Western

Since my original paper on the flint implements found in the Brown Boulder Clay of north-west Norfolk, I have continued my researches in that region, and now wish to give some account of these, and of the further specimens which have been discovered in this most recent boulder clay of East Anglia. I would take this opportunity of thanking the Trustees of the Percy Sladen Fund for their kindness in supporting this research with a money grant, and so enabling me to continue my examination of an era of much interest and importance to prehistoric archæology. I am also very grateful to my friends, Mr. J. B. Calkin, Mr. Guy Maynard, and Mr. J. S. Fisher, for the valuable help they have given me in carrying out the investigation of the Brown Boulder Clay.As is now widely known, this deposit, so far as Norfolk is concerned, is confined to the north-western portion of that county, and many years ago was examined and reported upon by the Geological Survey in two of their memoırs. The Brown Boulder Clay occurs approximately at sea-level at Hunstanton, while at Brancaster, as reported by Mr. Clement Reid, the deposit is exposed at low water upon the foreshore, underlying the ‘submerged forest’ which he saw there. At other places, such as Holkham brickfield, and the remarkable formation (probably a terminal moraine) in Hunstanton Park, the boulder clay rests at about 50 ft, above O.D.

scholarly journals Acceleration of Pine Island and Thwaites Glaciers, West Antarctica

2002 ◽  
Vol 34 ◽  
pp. 189-194 ◽  
Author(s):  
Eric Rignot ◽  
David G. Vaughan ◽  
Marjorie Schmeltz ◽  
Todd Dupont ◽  
Douglas Macayeal
Keyword(s):  
Mass Loss ◽  
Sea Level ◽  
Radar Interferometry ◽  
Constant Flow ◽  
West Antarctica ◽  
Ice Flow ◽  
Ice Surface ◽  
Grounding Line ◽  
Satellite Radar ◽  
Global Sea Level

AbstractRecent satellite investigations revealed that in the 1990s the grounding line of Pine Island and Thwaites Glaciers, West Antarctica, retreated several km, the ice surface on the interior of the basins lowered 10 cm a–1, and Pine Island Glacier thinned 1.6 ma–1. These observations, however, were not sufficient to determine the cause of the changes. Here, we present satellite radar interferometry data that show the thinning and retreat of Pine Island Glacier are caused by an acceleration of ice flow of about 18 ± 2% in 8 years. Thwaites Glacier maintained a nearly constant flow regime at its center, but widened along the sides, and increased its 30 ± 15% mass deficit by another 4% in 4 years. The combined mass loss from both glaciers, if correct, contributes an estimated 0.08 ± 0.03 mma–1 global sea-level rise in 2000.

scholarly journals The impact of sea-level rise on tidal characteristics around Australasia

2018 ◽  
Author(s):  
Alexander Harker ◽  
J. A. Mattias Green ◽  
Michael Schindelegger
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Tidal Dissipation ◽  
North West ◽  
The North ◽  
Arafura Sea ◽  
Coastal Features ◽  
Tidal Characteristics ◽  
Shelf Region ◽  
The Impact

Abstract. An established tidal model, validated for present-day conditions, is used to investigate the effect of large levels of sea-level rise (SLR) on tidal characteristics around Australasia. SLR is implemented through a uniform depth increase across the model domain, with a comparison between the coastal boundary being treated as impenetrable or allowing low-lying land to flood. The complex spatial response of the semi-diurnal constituents, M2 and S2, is broadly similar, with the magnitude of M2's response being greater. The most predominant features of this response are large amplitude changes in the Arafura Sea and within embayments along Australia's north-west coast, and the generation of new amphidromic systems within the Gulf of Carpentaria and south of Papua, once water depth across the domain is increased by 3 and 7 m respectively. Dissipation from M2 increases around the islands in the north of the Sahul shelf region and around coastal features along north Australia, leading to a notable drop in dissipation along Eighty Mile Beach. The diurnal constituent, K1, is found to be amplified within the Gulf of Carpentaria, indicating a possible change of resonance properties of the gulf. Coastal flooding has a profound impact on the response of tidal amplitudes to SLR, particularly K1, by creating local regions of increased tidal dissipation and altering the shape of coastlines.

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