Graham Land Research Articles

Products of subglacial volcanic eruptions under different ice thicknesses: two examples from Antarctica

Late Cenozoic, subglacially erupted volcanic sequences are scattered throughout the Antarctic Peninsula. Two of the best preserved examples, at Mount Pinafore (Alexander Island; c. 5.5–6 Ma) and Brown Bluff (Graham Land; c. 1 Ma), are complete enough to be regarded as sequence holotypes for this uncommonly preserved eruptive/depositional setting. Despite a common glacial association, the sedimentary lithofacies in the two outcrops suggest flowing and ponded water conditions, respectively, indicating significant differences in the depositional palaeoenvironments. The original ice thicknesses exerted a major control on the lithofacies which resulted from each eruptive phase. At Mount Pinafore, the lithofacies were confined within a steep-sided valley during successive eruptions beneath thin (100–150 m?), wet-based ice. The much thicker succession at Brown Bluff is a tindar-tuya edifice, which formed within a small basin (probably 15 km across) confined by ice 400 m thick.

Revised interpretations of Mesozoic palaeogeography and volcanic arc evolution in the northern Antarctic Peninsula region

Terrestrial sedimentary rocks at Hope Bay, northern Graham Land are well known for their diverse but poorly-preserved fossil flora, previously assigned ages ranging from Early Jurassic-Early Cretaceous. The beds form part of the Botany Bay Group, which comprises several outcrops of terrestrial sediments in northern Graham Land and the South Orkney Islands. A latest Jurassic or earliest Cretaceous age for the Hope Bay plant bearing sequence (and by extension for the rest of the Botany Bay Group) has been adopted in most recent publications dealing with Mesozoic volcanic arc evolution and palaeogeography of the northern Antarctic Peninsula region. New evidence, based upon the study of extensive collections of previously undescribed fossil plants from Hope Bay and nearby Botany Bay, indicates that they should be assigned an Early Jurassic age. The new palaeobotanical findings, combined with recently-published radiometric data from overlying volcanic sequences, show that a Cretaceous age is no longer tenable for these floras nor, therefore, for the Botany Bay Group in Graham Land. Interpretations of Mesozoic volcanic arc evolution and palaeogeography in this region are revised accordingly.

The bivalve Aulacomyella from the Early Tithonian (Late Jurassic) of Antarctica

The bivalve Aulacomyella is described formally from Tithonian deposits of the Antarctic Peninsula region for the first time. Two species are recognized. A. willeyi Kelly sp. nov. was collected in situ from the Nordenskjöld Formation, Longing Gap on the east coast of Graham Land, and in clasts reworked into Cretaceous glide block deposits on James Ross Island. A. cf. problematica Furlani is recorded from the Himalia Ridge Formation, Fossil Bluff Group, Alexander Island. These Antarctic records are the first published systematic descriptions of the genus from the Southern Hemisphere. Together with Mexican and Turkish records, they represent the last known occurrences of this genus. Globally the genus is particularly abundant during the Kimmeridgian and Early Tithonian stages and is therefore of value as a biostratigraphic indicator. It was almost certainly an epibyssate suspension feeder, although the precise palaeoecological setting for Aulacomyella is uncertain. It normally occurs in black shales or mudstones. The most likely life habits were either living epifaunally on the sea floor, where it bloomed under episodic dysaerobic conditions in an otherwise anaerobic environment, or pseudoplanktonically infesting floating sea weeds etc. Of these hypotheses the former is preferred here.

Late Jurassic—Early Cretaceous strike-slip deformation in the Nordenskjöld Formation of Graham Land

Upper Jurassic–Lower Cretaceous anoxic mudstones and air-fall ashes of the Nordenskjöld Formation are exposed on the eastern coast of Graham Land. Deformation of the strata has a long history spanning dewatering and lithification and was probably produced in a strike-slip tectonic regime. Available evidence suggests the onset of deformation in the region was during Tithonian times. The strike-slip deformation provides further evidence of a plate boundary along the eastern margin of the peninsula during the break-up of Gondwana and the movement of the crustal blocks of West Antarctica. It may also be related to a change in the spreading history of the Weddell Sea region and be the cause of a major facies change from fine anoxic to coarse clastic sedimentation.

Short paper: The significance of mid-Palaeozoic basement in Graham Land, Antarctic Peninsula

A mid-Palaeozoic basement to the Antarctic Peninsula is confirmed by a geochronological study of the gneissose country rock of the Mesozoic magmatic arc of eastern Graham Land. Rb–Sr whole-rock ages of 410 ± 15 and 426 ± 12 Ma from samples of orthogneiss indicate a previously unrecognized episode of granitic magmatism in the Antarctic Peninsula during the Silurian. Sm–Nd data on garnet–whole-rock pairs indicate that subsequent amphibolite facies metamorphism occurred in late Carboniferous times, probably as a result of plutonism.

Stratigraphy of the upper Jurassic-lower cretaceous Nordenskjöld Formation of eastern Graham Land, Antarctica

The Nordenskjöld Formation is a sequence of thinly interbedded ash beds and black, radiolarian-rich mudstones which is exposed on the eastern coast of the Antarctic Peninsula. As a result of recent field work, the Nordenskjöld Formation has been re-examined and redefined with three new members recognized — the Longing, Ameghino, and Larsen members. The age of the formation, based on its macrofossil content, is Kimmeridgian to Berriasian, although reworked clasts from James Ross Island suggest it might range down into the Oxfordian.

Climatic control of sedimentation in bays and fjords of the northern Antarctic Peninsula

The northern Antarctic Peninsula is dominated by strong climatic gradients, which are locally enhanced by subsidiary orographic and topographic effects. These gradients are reflected in the sediments of the bays and fjords of the region. The climate of the South Shetland Islands is relatively warm, with high levels of precipitation. This leads to a temperate glacial setting in which many glaciers terminate on land, and bay waters which are turbid with terrigenous debris. Sediments, which consist of terrigenous muds and sands with a low ice-rafted debris (IRD) content, are relatively thick (≈ 70 m) and have now filled in and almost completely mask the underlying basement topography. The Palmer Archipelago is colder than the South Shetland Islands, and is the wettest area of the Antarctic. It is heavily glaciated, and all major glaciers are grounded below sea level. Only rarely have sediment plumes been seen. The sediments, which are primarily terrigenous muds and sands with a variable IRD component, are thin (maximum ≈ 40 m) but are ponding in every available bathymetric depression. The pristine nature of the ice visible above sea level indicates that terrigenous debris is entering the bays from below sea level. Sediment gravity flows are important in redistributing sediment. The Danco Coast lies within the precipitation shadow of the Graham Land Plateau. Its climate is slightly colder, and is the driest in the study area, with less than half of the precipitation of the Palmer Archipelago. Nevertheless, it is also heavily glaciated. With few exceptions, sediments here are diatomaceous muds and oozes. They are very thin and drape across the rugged basement topography, rather than ponding in lows. Sediment gravity flow deposits are rare. These observations indicate a lower rate of production of terrigenous sediment here, a consequence of the drier climatic setting.

Southern Lights: The Account of the British Graham Land Expedition 1934-1937

Southern Lights: The Account of the British Graham Land Expedition 1934-1937

Britain's Antarctic dimension

During the decade or so prior to the Falklands War of 1982 there were clear signs that British governments were losing interest in the South-west Atlantic region as a whole, and consequently in the future of the British possessions located there, that is, the Falkland Islands, the Falkland Islands Dependencies (South Georgia, South Sandwich Islands) and British Antarctic Territory (South Orkneys, South Shetlands and the mainland sector centred upon Graham Land between 200 and 800 W). However, this situation was transformed by the Falklands War of AprilJune 1982, since this Anglo-Argentine conflict, which embraced both the Falklands and the Dependencies, resulted in the adoption of a more positive and committed British policy towards not only the islands regained from Argentine occupation but also the neighbouring British Antarctic Territory. There are, nevertheless, several elements of continuity in British policy towards Antarctica, including the maintenance of territorial claims to British Antarctic Territory, support for the continued development of the Antarctic Treaty system and an interest in the scientific research conducted by the British Antarctic Survey.' But since the Falklands War the South-west Atlantic has become an area of higher priority in official thinking, and this transformation of attitude has been accompanied by a large increase in the level of Britain's material commitment towards the Falklands, the Falkland Islands Dependencies and the British Antarctic Territory. Such developments offer a marked contrast to the position at the close of 1981 and during the early months of 1982, when the British government's policy towards the South-west Atlantic region was being criticized both in parliament and in the mass media for its lack of commitment to the area. For example, on 5 November 1981 Michael Shersby, a Conservative backbencher, expressed his concern on the matter, while a fuller debate and critique took place in the House of Lords' discussion inaugurated by Lord Morris on 16 December 1981.2 On 15 December an Early Day Motion was tabled in the House of Commons to the effect:

Rb-Sr geochronology of Graham Land, Antarctica

Thirty-five new Rb-Sr whole-rock and mineral isochrons are reported for igneous rocks from Graham Land. Magmatism was essentially continuous but peaks of activity occurred in early Jurassic, early Cretaceous, late Cretaceous and Eocene times. The oldest dated granite is Triassic (209 ± 3 Ma). Volcanic rocks were erupted throughout this history and some previously supposed Upper Jurassic volcanic rocks must be mid-Cretaceous or younger. A change in magma type, from uniformly acid to predominantly basic or intermediate, combined with westward migration of the arc, may be partly responsible for previously reported transverse geochemical variations. There is a marked trend of decreasing initial 87 Sr/ 86 Sr ratio of the plutonic rocks with time, from c. 0.707 to 0.704, although volcanic rocks tend to have higher values. This trend is ascribed to the waning influence of an, as yet unidentified, pre-magmatic crustal basement, due to increasing depth of magma generation. Close parallels to the observed age pattern imply continuity of the Andean belt through southern South America into Graham Land back to early Mesozoic times and are not compatible with reconstructions of Gondwana in which the Antarctic Peninsula is located W of South America.

Tectonic segmentation of the northern Antarctic Peninsula

Discrete segments of the southeast Pacific Ocean crust were subducted beneath the Antarctic Peninsula in Late Cretaceous and Cenozoic time. The segment boundaries of the subducted ocean crust are reflected in the overlying continental crust by transverse megafractures. These are usually obscured by contemporaneous magmatism but may be revealed by later fault movements. The transverse fracture zones divide Graham Land and its offlying islands into segments that have different histories of magmatism, uplift and erosion, and postorogenic sedimentation. Metalliferous mineralization is controlled, in part, by the transverse fracture zones.

British Antarctic Territory. Geological Map. Scale 1:500,000. Sheet 2. Northern Graham Land and South Shetland Islands. 1979. British Antarctic Survey. Copies available from Edward Stamford Ltd., 12–14 Long Acre, London WC2E 9LP. Price £5.00.

British Antarctic Territory. Geological Map. Scale 1:500,000. Sheet 2. Northern Graham Land and South Shetland Islands. 1979. British Antarctic Survey. Copies available from Edward Stamford Ltd., 12–14 Long Acre, London WC2E 9LP. Price £5.00. - Volume 117 Issue 6

Alone to Antarctica in Ice Bird

In 1974 Dr. David Lewis was awarded the Institute's Gold Medal for his work on indigenous navigation methods in the Pacific, and his many remarkable feats of practical navigation. The following account is of perhaps the most remarkable of his voyages which was an attempt to circumnavigate the Antarctic Continent on his own. The first part of the voyage, which culminated in January 1973, was mentioned in the formal citation for the award; the second part, which is every bit as remarkable, finished in Capetown in March 1974.No one had ever sailed single-handed through the Southern Ocean to any part of the Antarctic continent, not even by way of Drake Passage from Tierra del Fuego, which involves a crossing of only about 400 miles of open sea. Since the sole practicable Antarctic landfall for a small vessel is the Antarctic Peninsula (formerly Graham Land) below Cape Horn, Australia, some 6000 miles to the west, was a far from ideal starting point. However, this was where I was working so that there was no alternative but to make Sydney the point of departure.

Comments on the reported occurrence of ?Globo-Truncana Contusa (Cushman) from the upper Cretaceous of James Ross Island, Graham Land

Abstract Macfadyen (1966) described and illustrated a Cretaceous microfauna comprising seventeen species of foraminifera from glauconitic sandstones at Tumbledown Cliffs (lat. 64° 05’ S; long. 58° 27’ W), on the western side of James Ross Island, Antarctic Peninsula. Macfadyen notes that Howath (1958) regarded the ammonite assemblages of James Ross Island to be lower and middle Campanian in age and he accepted a similar age for the microfauna.

New Light on John Balleny

Captain Cook was apprenticed to the coal trade between Newcastle and London, then o e of the finest schools of seamanship, and for his first voyag round the world he had two colliers which were bought into the navy. John Balleny was in the same trade. We cannot say exactly when he went to sea, as it is almost impossible to trace seamen in the Merchant Service until they become masters. Nor is it possible to say where he was born and brought up. In 1798, John Balleny, living at St. George's in the East (which was then the shipping quarter of London) was, with two other men owner of the Blenheim, ship of 569 tons. In 1814 he was master ofthe Lord Cathcart trading between Liverpool and Marenham. In 1820 he was master of the brig Peace, 210/296 tons, built at Hull in 1809 and regularly trading from Shields. In November of that year, on a voyage from Yarmouth to London, the Peace went ashore on Corton Sand, not far from Yarmouth?not an unusual occurrence as hundreds of vessels passed each week through those intricate and poorly-lit waters?and got off again without great damage after the coals had been thrown overboard. Two years later Balleny was trading between Hull and Memel, bringing in fir timber, deal ends, pipe staves and flax. In 1823 be was noted as arriving at Sheerness in the Peace which he commanded until 1831. In 1824 be held an insurable interest in the Scottish whaling bark, the Caledonia, then in the Davis Straits fishery. The absence of his name from shipping records in the following years strongly suggests that he had retired from the sea.*1 In the 1830*8 Messrs. Charles, Henry and George Enderby twice sent vessels on Antarctic voyages. In 1830-3 John Biscoe discovered Enderby Land and Graham Land, but this voyage involved the firm in a financial loss. In 1833-4 tbey sent out the Hopefull and the Rose on an abortive search for new land and sealing grounds, which likewise ended in financial disaster. In 1838-9 they participated in a third Antarctic search in the Eliza Scott and the Sabrina, which proved to be no more profitable. In between them there was another unprofitable voyage of which little is known; when Biscoe reached the Falkland Islands in August 1832 he expected to find Messrs. Enderbys' smack, the Rose, with further intructions for his voyage, but he was disappointed as the Rose, having left England for the South Seas on 31 December 1831, returned to Limehouse in ballast on 22 June 1832.2 On 11 June 1838 Messrs. Enderby bought the Sabrina, a Cowes cutter of 476io tons (or 84*94 tons, old measurement), built at Southampton in 1821. On July 2 they sold 5364 to a group of merchants: Thomas Sturge 8 George Frederick Young 8 John William Buckle 7 William Beale 8 James Row 7 William Borradaile 7 William Brown 8

Operational Problems of Antarctic Aviation

Polar aviation is a branch of flying to which the domestic British (that is excluding the Canadians) have contributed modestly. Indeed, we do not have the Arctic on our doorstep like the Americans, Canadians, Russians, Finns, Swedes and Norwegians but, in exploration, we have a tradition second to none in Antarctica, a tradition fostered and developed in bygone years so dauntlessly by men of the Royal Navy. In fact it was Captain Robert Falcon Scott who was the first man ever to become airborne in Antarctica, early in January 1902, when he went aloft near Cape Adare in an observation balloon. Admittedly he let go all the ballast at once and shot up to 800 feet so rapidly that only the mooring rope prevented him from making a free-balloon voyage over the ice-bound wastes, and he did not enjoy the experience very much. But it was a pioneering flight. A few months later, the German Drygalski made a similar flight for the purpose of ice observation; but balloons never caught on in the Antarctic and there was no more flying there until Sir Hubert Wilkins’ expedition made the first aeroplane flight, from Deception Island, off Graham Land, with a Lockheed Vega wheeled aeroplane on 16th November 1928.

Antarctic Ecosystems The freshwater lakes of Signy Island and their fauna

Prior to 1962 work on freshwater within the British Sector of the Antarctic had been confined to the collection of specimens and their subsequent taxonomic evaluation. Collections were made by such expeditions as the Scottish National Antarctic Expedition 1902- 04, the various Discover y Investigations in this region 1925-37, the British Graham Land Expedition 1934-37 and the Falkland Islands Dependencies Survey 1945-62. During the 1961/1962 summer season an ecological investigation of the freshwater lakes of Signy Island, South Orkney Islands, was started. This paper is an interim report on that work.

The Cestode Parasites of the Sheathbill, Chionis alba (Gmelin), from Signy Island, South Orkney Islands

The Sheathbill is a distinctive bird breeding on the islands of the Scotia Arc and the Graham Land peninsula, and regularly occurring north to the Falkland Islands, the Magellanic Islands and the Atlantic coast of Argentina (Jones, 1963). Rather surprisingly no cestodes have previously been recorded or described from this bird.The following account describes Nototaenia fileri gen. et sp. nov. and Lateriporus ausiralis n.sp. from two of 13 adult Sheathbills collected on Signy Island in July and October 1965 by Mr Charles Howie of the British Antarctic Survey, preserved in deep-freeze, and later entrusted to us for examination.

Some Contrasts in Landscapes in British Antarctic Territory

Contrast is of the essence of regional description. Some lands, being possessed of st iking contrasts, have always lent themselves to easy?even over-facile? description. One thinks immediately of the contrast between the desert and the sown in the Nile valley, between mountain and plain in the Mediterranean world, between forest and steppe in historic Russia. In all these, and many other instances that will occur to you, there are strong physical contrasts of relief or climate or both together, reflected by contrasts in the natural vegetation and heightened by the handiwork of man. Clearly we can look for nothing of this kind in the Antarctic. Land vegetation is confined to a few moss-covered moraines and rock outcrops in the Antarctic islands of relatively low latitudes (the South Orkneys, 6i? S ; the South Shetlands 62?-63? S) and rare moss and lichen patches in northernmost Graham Land. Land animals are absent and the abundant sea mammals and sea birds are but summer visitors. Neither natural vegetation nor the handiwork of man can be said to soften or to modify the austerity of a landscape where ice in its many forms is dominant, and where naked rock brings welcome relief. It will therefore surprise no one in this audience if I suggest that landscape contrasts in the British Antarctic Territory1 are best discussed under those rather austere terms?structure, process and stage. Structure in the Antarctic means exactly what it means in south-east England, but in lands where nine-tenths or more of the surface is occupied by ice it has only a subordinate part to play in giving character to most landscapes. The chief role of structure is to determine the run of the main relief features or the broad disposition of physiographic provinces. Process is the dominant influence in landscape building and it takes two forms?the climatological process of glacierization in which the lands, and indeed the adjacent sea, may be progressively smothered by ice; and the geomorphological processes by which that ice in its slow descent from higher to lower altitudes and colder to warmer regions, has pared and sculptured the upstanding rock masses in ways to which the forms we now see bear witness. And lastly these forms reveal systematic differences that seem to find their most reasonable explanation if we attribute them to dif? ferent stages in the sequence of glacially sculptured forms. Considered in this way even Antarctic landscapes reveal a fascinating richness and variety. Structural considerations.?The area that I wish to consider lies southward of southernmost South America and has for more than half a century been recognized as having close geological relations with it. South of the fortieth parallel South America narrows abruptly as the immensity of the pampas comes to an end, and the continent continues in essentially peninsular form for another thousand miles. On the west the cordillera of the Andes enters its Magellanic phase, its summits blanketed by ice and snow, its western valleys deeply drowned and in the southern half fiorded. On the east the plateaus of Patagonia form a distinct major physio-

Probable Disintegration of Antarctica

The writer's research life has coincided fairly closely with the vast discoveries made in thi c ntury s nce he first joined the Sc tt Expedition to Antarctica in 1910. Nothing was known within the coasts of Antarctica until Scott had returned; indeed, until the end of 1904 the map merely showed a pear-shaped outline extending around the South Pole. In my first long memoir, which appeared in this Journal in 1914, I discussed generally the structure of Antarctica, and I especially stressed the resemblance between Antarctic and Australian structure ('Physiography and glacial geology of East Antarctica'; Geogr. J. 44 (1914) 365-82; 452-67; 553-71). I suggested that a broad syncline or downfold below sea level might extend from the Ross Sea to the Weddell Sea?somewhat as the Tasman Sea separated the folded New Zealand Ridge from the Horsts of Australia. Possibly this marine channel was present in midTertiary times. I have seen these suggestions to a considerable degree corroborated by the con? clusions ofthe I.G.Y. researches as seen in the recent topographic map published by the Scientific American in September 1962 (Antarctica: prepared by the American Geographical Society for the United States Antarctic Research Program, with a grant from the National Science Foundation: 1:5M. 1962). Two techniques have been developed in the Antarctic in the last thirty years? exploration by air, and echo-sounding through the ice cap. I may instance a few errors on the earlier maps. In 1914 Amundsen, as he sledged over the Ross Ice Shelf to the Pole, gave it as his opinion that 'Carmen Land' blocked my hypothetical geosyncline. This land was illusory: Scott's ship sailed over several so-called 'lands' in 1911 near Cape Adare (near d Fig. 1). Mawson found that many landfalls cited by Wilkes in 1840 were greatly out of position in this area. Wilkins, on his first flight in December 1928 charted 'Stefansson Strait' in approximately lat. 71 ? in such a position as to divide Graham Land from the Continent; this was later found to be an error. In 1940 was published in the Regionale Geologie der Erde of Leipzig (Bd. I: Die alten Kerne) my geological account of Antarctica which, though written in 1934, was more complete than anything that had been published before, and which was illustrated by a block diagram of Antarctica. In 1935 Ellsworth flew across from the Weddell Sea to the Ross Sea, and found that his 'Sentinel Range' (c) much prolonged the 'Antarctic-Andes' towards the Ross Sea. However, Byrd's aviator (Anderson) in 1936 reported that the 'Great Horst' extended for some 180 miles beyond the South Pole towards the Weddell Sea. The new sonic data reported as late as 1960 gave sonic and other inform? ation which seemed wholly to block the suggested geosyncline. The latest map, the American one discussed here, shows that the geosyncline, some 2000 miles long, and varying in width from 200 miles downwards until it narrows near the Horlick Mountains at the point marked * on Figure 1, is an actual feature. Recent soundings have shown that the Ross Shelf extends south-east for some 500 miles to the