Circum-Arctic Late Tertiary/Early Pleistocene stratigraphy and environments - a preface   /   Matthews, J.V.   Brigham-Grette, J.   Schweger, C.E.
Arctic, v. 43, no. 4, Dec. 1990, p. iii-iv
ASTIS record 33728

...During the 1980s the Geological Survey of Canada (GSC) and the U.S. Geological Survey (USGS) initiated a program of joint workshops and cooperative field excursions. The first meeting took place in Calgary, Alberta, in 1984. It dealt with correlation of Quaternary deposits in northwestern North America, but touched on the Tertiary. A second GSC/USGS workshop in early 1987 concerned the Quaternary history of interior basins of Alaska and Canada, but once again the Tertiary became an item of discussion because some of the basins contain a thick sequence of Pliocene and Miocene sediments. It was apparent from the questions that arose at these meetings that there was a need for a dedicated forum on the late Tertiary. The authors organized and convened a workshop with that theme in Denver, Colorado, in October 1987. The papers in this special issue are based on presentations and discussions at that meeting. ...

Tertiary marine events of the Beaufort-Mackenzie Basin and correlation of Oligocene to Pliocene marine outcrops in arctic North America   /   McNeil, D.H.
Arctic, v. 43, no. 4, Dec. 1990, p. 301-313, ill., 1 map
ASTIS record 30710

The benthic foraminiferal succession from the Beaufort-Mackenzie Basin of arctic Canada reflects many of the major oceanographic and climatic events of the Tertiary. The Paleocene-Eocene epochs are characterized by restricted marine circulation and pronounced foraminiferal endemism. Paleogeographic reconstruction illustrates that the Paleocene-Eocene Arctic Ocean was markedly different from its modern counterpart and it is thus referred to as the "Arctic Gulf." Marine connections between the Arctic and Atlantic oceans were broadened and deepened during the Oligocene. The Arctic Gulf thus evolved into a modern Arctic Ocean configuration by sea floor spreading in the Greenland-Norwegian Sea. The Oligocene index, Turrilina alsatica Andreae, appeared in the arctic regions concurrent with increased circulation between the North Atlantic and Arctic oceans. In the Beaufort-Mackenzie subsurface, Turrilina alsatica has proven to be a widespread and reliable zone index. In outcrop, it is known from only one locality, the Nuwok Member of the Sagavanirktok Formation on Carter Creek, Alaska. During the Miocene, increased circulation between the Arctic and Atlantic oceans was further established, and a moderate warming trend developed after a cool early Oligocene episode. The foraminifer Asterigerina staeschei (Franke) is an abundant and widespread marker of this phase of arctic marine history. Asterigerina staeschei became extinct in the middle Miocene in both the arctic and North Atlantic regions. In the Beaufort-Mackenzie Basin, many associated species ranged through into the late Miocene but disappear abruptly at the terminal Miocene unconformity. Major faunal and depositional sequence changes mark this as one of the most significant events in arctic Tertiary history, and the unconformity itself was caused by a widespread relative drop in sea level. A major faunal turnover in the Pliocene is characterized by Cibicides grossus ten Dam and Reinhold, which first appeared in the early Pliocene but became extinct through the North Atlantic and arctic regions at approximately 2.4 Ma, closely approximating the climate deterioration and initiation of continental glaciation in the late Pliocene. Cibicides grossus has a widespread distribution in arctic North America, occurring in the subsurface of the Beaufort-Mackenzie Basin and in outcrops of the marine tongue of the Beaufort Formation on Meighen Island, in unnamed strata on White Point of northwest Ellesmere Island, on eastern Baffin Island, and on eastern and northern Greenland.

Of mice and ice in the Late Pliocene of North America   /   Repenning, C.A.
Arctic, v. 43, no. 4, Dec. 1990, p. 314-323, ill., 1 map
ASTIS record 30711

Between 2.5 to 1.8 million years ago changes in arctic climate and in meadow mouse dispersal routes correlate with part of the history of uplift and glacial erosion of the Chugach and Saint Elias mountains in Alaska and adjacent Canada. Earlier meadow mice dispersing from Asia to central North America followed a southward coastal route between these mountains and the Pacific Ocean, appearing first in the United States Pacific Northwest. Two and a half million years ago, accelerated uplift of the Chugach and Saint Elias mountains milked Pacific westerly winds, enlarging the ice fields in these mountains so that they then flowed to the sea. This blocked the coastal dispersal for 600,000 years, when no new immigrant meadow mice appeared in the conterminous United States. The uplift also restrained westerly winds that crossed Canada, permitting moister air from the subtropical Atlantic and from an unfrozen Arctic Ocean to produce significant continental glaciation, centered in eastern Canada. By 2.0 million years ago, glacial erosion had lowered these mountains again, letting relatively dry Pacific westerlies extend across Canada, reducing the encroachment of moist Atlantic and arctic air, and ending continental glaciation to the east. The simultaneous reduction of glacial activity in the cordillera allowed meadow mice to renew southward dispersal. Additionally, the lowered mountains remained a rain shadow, causing grassland in the Great Plains of Canada. Thus a new dispersal route to the United States was opened for grazing meadow mice and for the first time their earliest records were in the Great Plains. Loss of the continental ice sheet and an unfrozen Arctic Ocean facilitated the northward spread of warm and moist air from the North Atlantic subtropical high; it flowed northward up the eastern front of the Rocky Mountains in the United States and, mingling with the dry westerlies, northeastward across Canada to northernmost Greenland, where trees then grew. About 1.8 million years ago the Great Plains of the United States were subtropical savannah and remained so until the beginning of the Ice Age 850,000 years ago.

Pollen and vertebrates of the early Neogene Haughton Formation, Devon Island, arctic Canada   /   Whitlock, C.   Dawson, M.R.
Arctic, v. 43, no. 4, Dec. 1990, p. 324-330, ill., maps
ASTIS record 30712

The Haughton Formation of northern Devon Island, arctic Canada, consists of sediments deposited in a lake that filled a large impact crater, which has been dated as early Miocene. The fossiliferous sediments contain a rich assemblage of pollen, some plant megafossils, and the only known early Neogene arctic vertebrates. Common pollen types are Pinus, Ericales, Corylus-type, Betula, and Alnus. Picea, Larix, Cupressaceae, and Ulmus/Zelkova also occur. These taxa, rarer hardwoods, and spores allow a vegetational reconstruction of a mixed conifer-hardwood forest. Climatic conditions were cool temperate with maritime influences. Vertebrates, including trout, smelt, swan, and four mammal genera, lend support to the climatic interpretation, and they also suggest considerable endemism for the mammals. The Haughton flora appears to be bracketed temporally by floras from various parts of the widely distributed Beaufort Formation.

Forest-tundra neighbouring the North Pole : Plant and insect remains from the Plio-Pleistocene Kap Kobenhavn Formation, North Greenland   /   Bennike, O.   Böcher, J.
Arctic, v. 43, no. 4, Dec. 1990, p. 331-338, ill., 1 map
ASTIS record 30713

The Kap Kobenhavn Formation in northeast Peary Land, Greenland, is believed to be 2.0-2.5 million years old, i.e., from the Plio-Pleistocene transition. The dating is primarily based on biostratigraphical correlation of lower marine fauna and a few fragments of terrestrial mammals. Although deposited in marine and coastal environments, the sediments contain abundant remains of terrestrial and limnic organisms. This paper examines macroscopic plant and insect remains. About 60 taxa of vascular plants and 120 insect taxa have so far been identified. Nearly all of the named insect species are extant, extralimital forms, generally of a recent subarctic/boreal and more or less circumpolar distribution. The species composition shows that upland areas were covered with forest-tundra and heathland and that mesotrophic, well-vegetated lakes and a number of other wetland localties existed in the area. The presence of arctic plants in the formation puts some time constraints on their origin.

Late Tertiary and early Pleistocene deposits and history of Banks Island, southwestern Canadian Arctic Archipelago   /   Vincent, J.-S.
Arctic, v. 43, no. 4, Dec. 1990, p. 339-363, ill., maps
ASTIS record 30714

Fossil-rich sediments on Banks Island provide an excellent record of events and conditions that prevailed in arctic Canada during the late Tertiary and Early Pleistocene. In the late Tertiary, fluvial sands and gravels of the Beaufort Formation and related deposits were laid down on the coastal plain facing the Beaufort Sea. Relative sea level was lower than today. Both mixed deciduous/coniferous and coniferous forests existed on Banks Island. Mean July temperatures must have been +10° C warmer than present. The Early Pleistocene Worth Point Formation records a period during which preglacial landscapes were modified by fluvial, eolian, and colluvial processes. Continuous permafrost was likely present, sea level was lower than today, and southern Banks Island was covered by an open larch-dominated forest-tundra. Mean July temperatures were probably some 5-7° C warmer than present. Although some evidence indicates possible earlier glaciations, the best record of an early continental ice advance is provided by widespread glacial and marine sediments of the Duck Hawk Bluffs Formation laid down during the Early Pleistocene Banks Glaciation. This advance was distinctly more extensive than Middle or Late Pleistocene ones and glacio-isostacically controlled sea levels were much higher than those of today. During the Early to Middle Pleistocene Morgan Bluffs Interglaciation, climate on Banks Island was cooler than in preglacial times. Although the tree line may have extended to the southern part of the island, fossil remains in seven localities indicate typical low arctic conditions (mean July temperatures 2-5° C warmer than present). Eustatic sea level was some 30 m higher than the present and permafrost was continuous. The Banks Island record provides critical information on periods when conditions in the Arctic were significantly warmer than today. As such it can serve as a basis to understand and forecast the nature and impact of future man-induced atmospheric warming.

Late Tertiary plant macrofossils from localities in Arctic/Subarctic North America : a review of the data   /   Matthews, J.V.   Ovenden, L.E.
Arctic, v. 43, no. 4, Dec. 1990, p. 364-392, ill., maps
ASTIS record 30715

Bryophyte and vascular plant fossils occur at many late Tertiary sites in Alaska and northern Canada. A number of these floras are received here. The oldest flora, possibly of late Early Miocene age, is probably the one from the Mary Sachs gravel at Duck Hawk Bluffs, Banks Island. The youngest are of early Quaternary age. The floras are of several types. The youngest (Cape Deceit Formation) contains only plants that grow in the Arctic and Subarctic today. The Meighen Island Beaufort Formation contains a few extinct taxa (Aracites globosa) and fossil plants, such as Sambucus, Comptonia, and Physocarpus, that are not found in the present subarctic and arctic regions of North America. Some of these floras also contain fossils of a five-needle pine that may represent the Japanese Stone pine (Pinus pumila). A third group of floras, from Cone Bluff and Lava Camp, Alaska, usually contains more extinct plants (Epipremnum crassum, Decodon and cf. Paliurus) as well as fossils of pines in the subsection Cembrae. The Mary Sachs gravel flora, with taxa such as Metasequoia, Glyptostrobus, Taxodium, Juglans, and Liriodendron, stands apart from all three of the above-mentioned floral types. The Mary Sachs gravel flora represents mixed coniferous and hardwood forests. Most of the other floras represent coniferous forests that were floristically richer than present boreal forest. Some of the richness is due to taxa now found only in Eurasia. The Meighen Island Beaufort flora and some of those from the high-level alluvium on Ellesmere Island represent forest tundra. Several lines of evidence show that the Beaufort Formation on Meighen Island in the Canadian Arctic is about 3 million years old. Several of the younger floras contain abundant, well-preserved bryophyte fossils. Unlike the vascular plants, all of them represent extant species.

Beaufort Formation (Late Tertiary) as seen from Prince Patrick Island, Arctic Canada   /   Fyles, J.G.
Arctic, v. 43, no. 4, Dec. 1990, p. 393-403, ill., maps
ASTIS record 30716

The Beaufort Formation, in its type area on Prince Patrick Island, is a single lithostratigraphic unit, a few tens of metres thick, consisting of unlithified sandy deposits of braided rivers. Organic beds in the sand have yielded more than 200 species of plants and insects and probably originated during the Pliocene, when the area supported coniferous forest. This Beaufort unit forms the thin eastern edge of a northwest-thickening wedge of sand and gravel beneath the western part of the island. These largely unexposed beds, up to several hundred metres thick, include the Beaufort unit and perhaps other older or younger deposits. On the islands northeast and southwest of Prince Patrick Island (Meighen Island to Banks Island), the name Beaufort Formation has been applied to similar deposits of late Tertiary age. Most recorded Beaufort beds on these islands are stratigraphically and paleontologically equivalent to the "type" Beaufort, but a few sites that have been called Beaufort (such as Duck Hawk Bluffs and the lower unit at Ballast Brook, on Banks Island) differ stratigraphically and paleontologically from the "type" Beaufort. This paper recommends that these deposits (probably middle Miocene) and others like them be assigned new stratigraphic names and not be included in the Beaufort Formation as now defined. Informal names Mary Sachs gravel (Duck Hawk Bluffs) and Ballast Brook beds are proposed as an initial step. Formal use of the name Beaufort Formation should be restricted to the western Arctic Islands.

John Howard Sissons (1892-1969)   /   de Weerdt, M.M.
Arctic, v. 43, no. 4, Dec. 1990, p. 404-405, ill.
ASTIS record 31105

Dubbed a "living legend" in his own lifetime, the late Honourable John Howard Sissons is still remembered as a staunchly independent, even idiosyncratic, pioneer judge during the critical years 1955-66 in the Northwest Territories of Canada. ... As recently as January 1990, Natural History ... published an article entitled "Images of Justice," which features some of the Inuit carvings donated by "Judge Sissons" ... to the Sissons-Morrow Collection on display in the Court House at Yellowknife. These carvings and the article based on them illustrate the extraordinary period during which Sissons held office as the only resident judge of what was then the Territorial Court of the Northwest Territories in the eleven-year period following his appointment to that office in 1955. Each of the carvings depicts, with a good deal of artistic licence, a scene that calls up the facts of a case that came before the Territorial Court (renamed the Supreme Court of the Northwest Territories in 1972) either in Sisson's time or that of his successor the (now late) Mr. Justice William George Morrow. ... The collection is believed to be unique and draws many visitors to the Court House who would otherwise not go there. ... Tempering the rigours of the Criminal Code and of the rules of evidence and criminal procedure to meet the exigencies of the situation before him, Sissons frequently decided the case (or directed the jury to do so) with a view to ensuring that justice was done with due regard for the cultural factors present. He saw himself, and no doubt acted, as the champion of the underdog, usually the accused person in a criminal case. He would, nevertheless, convict an accused where the accused was clearly shown to be guilty and the victim of the offence had clearly been wronged by the accused, .... Native customs in relation to marriage and child adoption were recognized by Sissons in a series of cases in the 1960s. The precedents that he set in respect of child adoptions by native custom were later upheld by the Court of Appeal of the Northwest Territories and are still frequently applied by the Supreme Court of the Northwest Territories. An important element of the native heritage has in this way been preserved by the courts following his early lead. ...

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