scholarly journals History of views on the relative positions of Antarctica and South America: A 100-year tango between Patagonia and the Antarctic Peninsula

2007 ◽  
Author(s):  
H. Miller
Keyword(s):  
South America ◽  
Antarctic Peninsula ◽  
History Of ◽  
The Antarctic

Holocene glacier history of northeastern Cordillera Darwin, southernmost South America (55°S)

2021 ◽  
pp. 1-16
Author(s):  
Scott A. Reynhout ◽  
Michael R. Kaplan ◽  
Esteban A. Sagredo ◽  
Juan Carlos Aravena ◽  
Rodrigo L. Soteres ◽  
...  
Keyword(s):  
South America ◽  
Last Millennium ◽  
Glacial History ◽  
Dry Period ◽  
The North ◽  
Southward Shift ◽  
History Of ◽  
Glacial Expansion ◽  
The Antarctic ◽  
Glacial Advance

Abstract In the Cordillera Darwin, southernmost South America, we used 10Be and 14C dating, dendrochronology, and historical observations to reconstruct the glacial history of the Dalla Vedova valley from deglacial time to the present. After deglacial recession into northeastern Darwin and Dalla Vedova, by ~16 ka, evidence indicates a glacial advance at ~13 ka coeval with the Antarctic Cold Reversal. The next robustly dated glacial expansion occurred at 870 ± 60 calendar yr ago (approximately AD 1150), followed by less-extensive dendrochronologically constrained advances from shortly before AD 1836 to the mid-twentieth century. Our record is consistent with most studies within the Cordillera Darwin that show that the Holocene glacial maximum occurred during the last millennium. This pattern contrasts with the extensive early- and mid-Holocene glacier expansions farther north in Patagonia; furthermore, an advance at 870 ± 60 yr ago may suggest out-of-phase glacial advances occurred within the Cordillera Darwin relative to Patagonia. We speculate that a southward shift of westerlies and associated climate regimes toward the southernmost tip of the continent, about 900–800 yr ago, provides a mechanism by which some glaciers advanced in the Cordillera Darwin during what is generally considered a warm and dry period to the north in Patagonia.

scholarly journals A description and summary of the Antarctic Humpback Whale Catalogue

2020 ◽  
pp. 95-99
Author(s):  
Judith Allen ◽  
Carole Carlson ◽  
Peter T. Stevick
Keyword(s):  
South America ◽  
Southern Ocean ◽  
Antarctic Peninsula ◽  
Humpback Whale ◽  
Humpback Whales ◽  
Western Coast ◽  
Long Distance ◽  
Dorsal Fin ◽  
Feeding Area ◽  
The Antarctic

The Antarctic Humpback Whale Catalogue (AHWC) is an international collaborative project investigating movement patterns of humpback whales in the Southern Ocean and corresponding lower latitude waters. The collection contains records contributed by 261 researchers and opportunistic sources. Photographs come from all of the Antarctic management areas, the feeding grounds in southern Chile and also most of the known or suspected low-latitude breeding areas and span more than two decades. This allows comparisons to be made over all of the major regions used by  Southern Hemisphere humpback whales. The fluke, left dorsal fin/flank and right dorsal fin/flank collections represent 3,655, 413 and 407 individual whales respectively. There were 194 individuals resighted in more than one year, and 82 individuals resighted in more than one region. Resightings document movement along the western coast of South America and movement between the Antarctic Peninsula and western coast of South America and Central America. A single individual from Brazil was resighted off South Georgia, representing the first documented link between the Brazilian breeding ground and any feeding area. A second individual from Brazil was resighted off Madagascar, documenting long distance movement of a female between non-adjacent breeding areas. Resightings also include two matches between American Samoa and the Antarctic Peninsula, documenting the first known feeding site for American Somoa and setting a new long distance seasonal migration record. Three matches between Sector V and eastern Australia support earlier evidence provided by Discovery tags. Multiple resightings of individuals in the Antarctic Peninsula during more than one season indicate that humpback whales in this area show some degree of regional feeding area fidelity. The AHWC provides a powerful non-lethal and non-invasive tool for investigating the movements and population structure of the whales utilising the Southern Ocean Sanctuary. Through this methodical, coordinated comparison and maintenance of collections from across the hemisphere, large-scale movement patterns may be examined, both within the Antarctic, and from the Antarctic to breeding grounds at low latitudes.

New trigonioid bivalves from the Early Jurassic to earliest Cretaceous of the Antarctic Peninsula region: systematics and austral paleobiogeography

1995 ◽  
Vol 69 (1) ◽  
pp. 66-84 ◽  
Author(s):  
Simon R. A. Kelly
Keyword(s):  
New Zealand ◽  
Antarctic Peninsula ◽  
Southern Africa ◽  
Late Jurassic ◽  
Early Jurassic ◽  
South Shetland Islands ◽  
Shetland Islands ◽  
Livingston Island ◽  
History Of ◽  
The Antarctic

New discoveries of trigonioid bivalves are documented from three areas in the Antartic Peninsula: the Fossil Bluff Group of Alexander Island, the Latady Formation of the Orville Coast, and the Byers Group of Livingston Island, South Shetland Islands. Eleven taxa are described, representing six genera or subgenera. The faunas are characterized by genera including Vaugonia (Vaugonia), the first Early Jurassic trigonioid recognized on the continent; Vaugonia (V.) and V. (Orthotrigonia?) in the Late Jurassic; and Iotrigonia (Iotrigonia), Myophorella (Scaphogonia), and Pterotrigonia (Pterotrigonia), which span the Jurassic–Cretaceous boundary, reaching the Berriasian stage. The following species are new: Pterotrigonia (P.) cramei n. sp., Pterotrigonia (P.) thomsoni n. sp., Vaugonia (V.) orvillensis n. sp., and V. (Orthotrigonia?) quiltyi n. sp. The faunas show affinities with those of New Zealand and southern Africa. Trigonioids characterize the shallower marine biofacies in the Jurassic of the Antarctic and reflect the principal shallowing events in the history of the region.

scholarly journals Electrical Resistivity of Ice from the Antarctic Peninsula, Antarctica

1984 ◽  
Vol 30 (106) ◽  
pp. 289-295 ◽  
Author(s):  
John M. Reynolds ◽  
J. G. Paren
Keyword(s):  
Antarctic Peninsula ◽  
Flow Line ◽  
Polar Regions ◽  
List Type ◽  
Electrical Measurements ◽  
Ice Shelf ◽  
Ice Shelves ◽  
History Of ◽  
Surface Ice ◽  
The Antarctic

AbstractGeoresistivity soundings have been carried out at four sites in the Antarctic Peninsula. The objective of the work was to investigate the electrical behaviour of ice from an area where substantial melting occurs in summer and from contrasting thermal regimes. Electrical measurements made at three sites along a flow line within George VI Ice Shelf reveal that:(a)the resistivity of deep ice is similar to that of other Antarctic ice shelves,(b)the resistivity of the ice-shelf surface, which is affected by the percolation and refreezing of melt water, is similar to that of deep ice and hence the ice is polar in character.A compilation of published resistivities of deep ice from polar regions shows that the range of resistivities is very narrow (0.4 –2.0) x 105Ω m between –2 and – 29°C, irrespective of the physical setting and history of the ice. Typically, resistivity is within a factor of two of 80 kΩ m at –20° C with an activation energy of 0.22 eV. In contrast, the resistivity of surface ice at Wormald Ice Piedmont, where the ice is at 0°C throughout, is two orders of magnitude higher and falls at the lower end of the range of resistivities for temperate ice.

New trigonioid bivalves from the Albian (Early Cretaceous) of Alexander Island, Antarctic Peninsula: systematics, paleoecology, and austral Cretaceous Paleobiogeography

1995 ◽  
Vol 69 (2) ◽  
pp. 264-279 ◽  
Author(s):  
Simon R. A. Kelly
Keyword(s):  
South America ◽  
East Africa ◽  
Antarctic Peninsula ◽  
Early Cretaceous ◽  
Southern South America ◽  
The Antarctic ◽  
Molluscan Assemblage ◽  
Faunal Similarity

Newly discovered trigonioid bivalves are systematically described from the Late Albian of the Fossil Bluff Group of Alexander Island, Antarctic Peninsula. The fauna includes Nototrigonia (Nototrigonia) ponticula Skwarko, N. (Callitrigonia) offsetensis n. sp., Eselaevitrigonia macdonaldi n. sp., Pterotrigonia (Pisotrigonia) capricornia (Skwarko), and Pacitrigonia praenuntians n. sp. It represents the first Albian trigonioid fauna described from the Antarctic. It is also the first published record of the Nototrigoniinae (excluding Pacitrigonia) outside Australasia. Paleoecologically, this fauna represents the shallowest and highest energy molluscan assemblage from the Fossil Bluff Group and occurs near the base of a significant transgressive unit, the Mars Glacier Member of the Neptune Glacier Formation. The paleogeography of Austral Cretaceous trigonioids is reviewed. Endemic centers are identified in India–east Africa, southern South America, and Australasia. Only one trigonioid genus, Pacitrigonia, had its origin in the Antarctic. During the earliest Cretaceous, cosmopolitan trigonioid genera occurred in Antarctica. In the mid-Cretaceous faunal similarity of Antarctica with Australasia was strong, and in the latest Cretaceous affinity with southern South America increased.

A new estimate of the adopted gravity value at Rothera Station, Antarctic Peninsula

1999 ◽  
Vol 11 (4) ◽  
pp. 461-462 ◽  
Author(s):  
Philip C. Jones ◽  
Julie K. Ferris
Keyword(s):  
South America ◽  
Antarctic Peninsula ◽  
Base Station ◽  
Falkland Islands ◽  
Gravity Station ◽  
Gravity Network ◽  
Scientific Station ◽  
The Uk ◽  
The Antarctic ◽  
Gravity System

Because of the lack of a definitive air link to an international gravity base station, the Antarctic Peninsula gravity network was originally, and still is, tied to the Potsdam gravity system via long ship links to South America (Renner 1981, Kennett 1965). An indirect link from the British Antarctic Survey (BAS) scientific station at Rothera to an International Gravity Standardisation Net 1971 (IGSN 71) base station in the UK had previously been made via a link to the BAS gravity station on the Falkland Islands in Port Stanley (McGibbon 1988). Whilst the apparent gravity difference between Port Stanley and the base station in the UK had been calculated via a two-way air tie using a LaCoste and Romberg meter (McGibbon 1988) and later strengthened with three two-way air ties using four LaCoste and Romberg meters (Bassett 1987), the link between Port Stanley and Rothera was based on a one-way tie that included a lengthy ship borne passage (McGibbon 1988). The weakness of this link insured that the adopted gravity value at Rothera continued to be based on the ship ties made by Griffiths et al. (1964) and Kennett (1965). This note describes the strengthening of the gravity link between Rothera and Port Stanley and the subsequent reassignment of the adopted gravity value at Rothera Station.

scholarly journals Glacier Fluctuations in George VI Sound Area, West Antarctica (Abstract only)

1982 ◽  
Vol 3 ◽  
pp. 345 ◽  
Author(s):  
C.M. Clapperton ◽  
D.E. Sugden
Keyword(s):  
Antarctic Peninsula ◽  
Ice Age ◽  
List Type ◽  
West Antarctica ◽  
Ice Shelf ◽  
Scotia Sea ◽  
Field Evidence ◽  
Glacial Chronology ◽  
History Of ◽  
The Antarctic

George VI Sound lies between Alexander Island and the Antarctic Peninsula and is over 20 km wide and 500 km long. At present an ice shelf fills the sound and is nourished largely by ice from the Antarctic Peninsula which flows across the sound to ground against the coast of Alexander Island. Ice-free areas, comprising small nunataks and larger massifs, fringe both sides of the sound and contain evidence of the former glacial history of the area. This paper describes the field evidence in detail and uses geomorphological and sedimentary analyses to put forward a relative glacial chronology, constrained by two absolute dates. The chronology distinguishes: (1) a maximum state during which all ice-free areas were submerged by ice flowing into George VI Sound from both the Antarctic Peninsula and Alexander Island and thence along the sound as an ice stream. This occurred in the late Wisconsin and followed an interstadial or interglacial when George VI Sound was free of an ice shelf. (2) a valley-based stadial during overall deglaciation represented by pronounced marginal moraines on Alexander Island. (3) deglaciation to a stage where there was less landbased ice on Alexander Island than today. At this stage isostatic recovery was incomplete, relative sealevel was higher, and George VI Ice Shelf penetrated further into embayments on Alexander Island than at present. (4) probable disappearance of George VI Ice Shelf by 6.5 14C ka BP. (5) neoglacial readvance of local glaciers on Alexander Island to form three closely spaced terminal moraines and the growth of a new George VI Ice Shelf which was again more extensive than at present. (6) subsequent oscillations of both smaller Alexander Island glaciers and George VI Ice Shelf probably during the Little Ice Age. These fluctuations are similar to those in other sub-Antarctic Islands in the Scotia Sea and also in southern Chile.

Sign in / Sign up

Export Citation Format

Share Document