Interpretation of the Gravity Anomaly at Darnley Bay, N.W.T.

1971 ◽  
Vol 8 (8) ◽  
pp. 1037-1042 ◽  
Author(s):  
R. A. Stacey
Keyword(s):  
Gravity Anomaly ◽  
Background Field ◽  
The Body ◽  
Shallow Depth ◽  
The Arctic ◽  
Mackenzie Delta ◽  
Early Paleozoic ◽  
Truncated Cone ◽  
Arctic Coast

The almost circular gravity anomaly which lies at the head of Darnley Bay on the Arctic coast 400 km east of the Mackenzie Delta, has a radius of 50 km with Bouguer values rising 130 mgal above the background field. It is concluded that the anomaly is due to a basic or ultrabasic body in the form of a truncated cone (which may narrow towards the surface or downwards), lying at a comparatively shallow depth within the Proterozoic sediments. Having obtained a feasible configuration for the body, the influence it may have had on the deposition of later Proterozoic and early Paleozoic sediments is discussed in speculative terms.

External scarring of whitefish, Coregonus nasus and C. clupeaformis complex, from the western Northwest Territories, Canada

1987 ◽  
Vol 65 (5) ◽  
pp. 1230-1239 ◽  
Author(s):  
J. D. Reist ◽  
R. A. Bodaly ◽  
R. J. P. Fudge ◽  
K. J. Cash ◽  
T. V. Stevens
Keyword(s):  
Arctic Ocean ◽  
Northwest Territories ◽  
Lateral Line ◽  
Parasitic Copepod ◽  
The Body ◽  
The Arctic ◽  
Mackenzie Delta ◽  
Unequal Distribution ◽  
Gill Net ◽  
The Arctic Ocean

Up to 40% of whitefish (Coregonus nasus and C. clupeaformis) sampled during spawning migrations from the area of the Mackenzie Delta, N.W.T., had external scars. Percent frequency of scarred individuals varied geographically from the Mackenzie mainstem and tributaries, where 20% were scarred, to Anderson river (2%), Cox Lake (16%), and Alaska (0–7%). Within the Mackenzie system fish captured at mainstem locations had approximately twice the frequency of scarring than did fish from tributary locations. Scars were classified as either slash or round type. Both scar types were located more frequently on the left side of the fishes and below the lateral line. Details of orientation and location on the body provided clues permitting the assignment of putative causation. Small round scars were restricted to locations with connections to the Arctic Ocean and were probably caused by the marine parasitic copepod Coregonicola or by Arctic lampreys (Lampetra japonica). Larger round scars were either the result of attacks by lampreys or by previous gill net capture. Unequal distribution and orientation on the body of slash scars indicated previous capture in gill nets or predation attempts by bears, birds, or piscivorous fishes.

Late Eskimo Archaeology in the Western Mackenzie Delta Area

1952 ◽  
Vol 18 (1) ◽  
pp. 30-39
Author(s):  
Douglas Osborne
Keyword(s):  
New Mexico ◽  
The Arctic ◽  
Mackenzie Delta ◽  
American Philosophical Society ◽  
Delta Area ◽  
University Of New Mexico ◽  
Arctic Coast ◽  
Mackenzie River

Although the American Philosophical Society–University of New Mexico Mackenzie Valley Expedition of 1938 (Bliss, 1939, p. 365) was not primarily concerned with Eskimo archaeology, the members felt, while at the trading rendezvous Aklavik on the lower Mackenzie River, that the opportunity to run down to the Arctic coast was too obvious to be neglected. The archaeology of the Western Eskimo of the Mackenzie area has never been well studied; little, as a matter of fact, has been added since 1930 when Mathiassen wrote the introduction to his Western Eskimo report. This paper will add somewhat to a meager store of fact.

Pleistocene geology and geomorphology of the Smoking Hills Upland and lower Horton River Arctic coast of mainland Canada

1989 ◽  
Vol 26 (9) ◽  
pp. 1677-1687 ◽  
Author(s):  
William H. Mathews ◽  
J. Ross Mackay ◽  
Glenn E. Rouse
Keyword(s):  
Sediment Transport ◽  
Early Pleistocene ◽  
The Arctic ◽  
Mackenzie Delta ◽  
Indirect Influence ◽  
Drainage Patterns ◽  
Arctic Coast ◽  
Peripheral Areas ◽  
Late Wisconsinan ◽  
Intermediate Surface

The Smoking Hills Upland and lower Horton River valley, on the Arctic coast of Canada 300 km east of the Mackenzie Delta, retain an extended record of subaerial erosion of nearly flat-lying Cretaceous shales. This erosion led to the development of (i) a very gently sloping low-relief upland surface (Early Pleistocene(?)), (ii) a slightly steeper intermediate surface, and (iii) younger steep valley walls, terraces, and broad valley bottoms. No direct glacial contribution to any of these landforms can be recognized. An early interglacial(?) fluvial episode is recorded in plateau-cap sediments. Suggestions of an early (mid-Pleistocene or earlier) glaciation overwhelming the Smoking Hills Upland are found in (i) anomalies in drainage patterns, (ii) disturbances in bedding, believed to have been caused by ice thrusting, and (iii) local occurrences of diamictons. Later, probably Early Wisconsinan, glaciation left meltwater channels in peripheral areas. The Late Wisconsinan ice sheet did not reach the Smoking Hills Upland but may have had an indirect influence by modyfying discharge and sediment transport of Horton River.

The Last Interglaciation in Northeast Siberia

1995 ◽  
Vol 43 (2) ◽  
pp. 147-158 ◽  
Author(s):  
Anatoly V. Lozhkin ◽  
Patricia M. Anderson
Keyword(s):  
General Circulation ◽  
General Circulation Models ◽  
The Arctic ◽  
The North ◽  
River Terraces ◽  
Atmospheric General Circulation ◽  
Winter Temperatures ◽  
Atmospheric General Circulation Models ◽  
Arctic Coast ◽  
Organic Deposits

AbstractAlluvial, fluvial, and organic deposits of the last interglaciation are exposed along numerous river terraces in northeast Siberia. Although chronological control is often poor, the paleobotanical data suggest range extensions of up to 1000 km for the primary tree species. These data also indicate that boreal communities of the last interglaciation were similar to modern ones in composition, but their distributions were displaced significantly to the north-northwest. Inferences about climate of this period suggest that mean July temperatures were warmer by 4 to 8°C, and seasonal precipitation was slightly greater. Mean January temperatures may have been severely cooler than today (up to 12°C) along the Arctic coast, but similar or slightly warmer than present in other areas. The direction and magnitude of change in July temperatures agree with Atmospheric General Circulation Models, but the 126,000-year-B.P. model results also suggest trends opposite to the paleobotanical data, with simulated cooler winter temperatures and drier conditions than present during the climatic optimum.

Salinity tolerance of larval and juvenile broad whitefish (Coregonus nasus)

1989 ◽  
Vol 67 (10) ◽  
pp. 2392-2397 ◽  
Author(s):  
B. G. E. de March
Keyword(s):  
Salinity Tolerance ◽  
Species Distribution ◽  
Laboratory Experiments ◽  
Larval Fish ◽  
The Arctic ◽  
Distribution Data ◽  
Migratory Fish ◽  
Limited Information ◽  
Time To Death ◽  
Arctic Coast

In the absence of distribution data for juvenile broad whitefish, Coregonus nasus, laboratory experiments were designed to elucidate the salinity ranges that the species will tolerate. Larval fish (12–18 mm) died within 120 h at salinities of 12.5‰ and higher at both 5 and 10 °C, though more slowly at 5 °C. Salinities of 12.5 and 15‰, but no higher, were tolerated for 120 h at 15 °C. Larvae fed readily at 15 °C but not at 5 or 10 °C. Slightly larger and more-developed larvae (15–19 mm) were tolerant of 12.5‰ but died within 120 h at 15‰ at the same three temperatures. These fish fed more readily than the younger ones. Larger fish (33–68 mm) were generally tolerant of 15–20‰ but not of higher salinities in 120-h tolerance tests. Larger field-collected fish (27–200 mm) reacted similarly but were more tolerant of salinities between 20 and 27‰ in 96-h tests. Analysis of both experiments with larger fish suggests that time to death was inversely related to size as well as to salinity. Coregonus nasus does not seem to be more tolerant of saline conditions than other freshwater or migratory fish species. Experimental results combined with limited information about the species' distribution suggest that man-made constructions on the arctic coast might seriously affect dispersal or annual migrations.

scholarly journals A Photographic Record of the Upper Headwater Tributaries, Basins and Riparia of the Snake River

2011 ◽  
Vol 33 ◽  
pp. 107-113
Author(s):  
Susan Green ◽  
Dr. Michael Krop
Keyword(s):  
Global Warming ◽  
World War Ii ◽  
The Arctic ◽  
Snake River ◽  
Glacier Bay ◽  
Tundra Vegetation ◽  
The Us ◽  
Arctic Coast ◽  
Vantage Points ◽  
Bear Management

Photographic surveys have been used since the early 1940’s to document coastlines, fuel supplies and river courses. The US Navy, post world war II, flew over the Arctic coast to document possible locations for oil extraction. These very same photos are now being utilized to compare changes in tundra vegetation at the same locations today. John Muirs’ photos of Glacier Bay are a startling testament to the melted glaciers no longer visible from the same vantage point in present times. Taking photographs to monitor change may not tell the entire story behind a change in landscape. However, photos taken over a number of years from the same vantage points, can help monitor landscape changes due to habitat fragmentation, global warming, forest fire, cattle grazing and other land management issues. Photo monitoring is inexpensive, simple and can portray change to many different groups. Of course, photos taken to reveal change must start with documenting current or normal conditions. This is sometimes called baseline monitoring. The park ranger in Glacier National Park did not realize when he took his picture of the Grinnell glacier in 1911 that his photo would become an alarming baseline photo for evidence of global warming. The purpose of this project was to document the Snake River headwater basin and its riparian zones as a document in time for future reference. The original documentation included 48 images of two main headwater areas; the Shoshone and Lewis Lake areas and the Fox Park-Two Ocean Bear Management Areas near the Yellowstone Park border. Since the Shoshone-Lewis lakes are easily assessable and photo space here is limited, I have chosen to only use photos from the more remote areas.

Thermal Design of Pipelines – A Challenge for Flow Assurance in the Arctic

2021 ◽  
Author(s):  
Veerendhar Ponagandla ◽  
Liangjian Liu ◽  
Duane DeGeer
Keyword(s):  
Heat Loss ◽  
Optimal Solution ◽  
Thermal Design ◽  
The Arctic ◽  
Flow Assurance ◽  
Mackenzie Delta ◽  
Far North ◽  
Hypothetical Scenario ◽  
Surface Ice ◽  
The Impact

Abstract Increasing demand for energy is driving the need to explore the deeper oceans and the far north. While higher temperature, pressure and longer tie-backs are challenges going deep, highly sensitive environment is an issue exploring far north. The discovery of large reserves in the far north has brought the challenges of exploration, production, and transportation in the cold regions like Prudhoe Bay, the Mackenzie Delta, and the Arctic Islands into focus. To transport hydrocarbons to market, pipelines used in the Arctic have unique challenges and stringent design conditions that must be met to ensure reliable operations in such remote and sensitive environments. To avoid flow assurance risks, the adage “the hotter the better” is in stark contrast to the sensitive nature of the Arctic environment to temperature changes, and where “the colder the better” is more appropriate. Permafrost, and its potential disturbance, is the most important factor to be considered for pipeline thermal design. High temperatures can disturb the in-situ state of the permafrost, causing settlement and instability in the permafrost zone. Also, high pipeline temperatures demand deep trenches to avoid melting the surface ice, challenging installation and increasing CAPEX. Designing the pipeline to maintain high internal fluid temperatures to reduce flow assurance risks and lower pipeline outer temperatures to minimize the impact on the environment is the best solution. To maintain high fluid temperatures and reduce heat loss to the environment, the conventional idea of a high value insulation like pipe-in-pipe with a vacuum annulus to avoid heat loss to the sensitive Arctic surroundings may seem to be a good solution, but it may not be the optimal solution. This paper discusses a hypothetical scenario (based on field cases) of a multiphase pipeline design and highlights the associated flow assurance/operational risks.

scholarly journals Large-Scale Variation in Growth of Black Brant Goslings Related to Food Availability

The Auk ◽  
2001 ◽  
Vol 118 (4) ◽  
pp. 1088-1095 ◽  
Author(s):  
James S. Sedinger ◽  
Mark P. Herzog ◽  
Brian T. Person ◽  
Morgan T. Kirk ◽  
Tim Obritchkewitch ◽  
...  
Keyword(s):  
Large Scale ◽  
Grazing Pressure ◽  
The Arctic ◽  
First Year ◽  
Principal Mechanism ◽  
Density Dependent ◽  
Brood Rearing ◽  
Branta Bernicla ◽  
Black Brant ◽  
Arctic Coast

AbstractWe examined variation in growth of Black Brant (Branta bernicla nigricans) goslings among two colonies on the Yukon-Kuskokwim Delta in southwestern Alaska and the Colville River Delta on Alaska's Arctic coast. We simultaneously measured abundance and quality of a key food plant, Carex subspathacea, and grazing pressure on that plant at the three colonies. Our goal was to measure variation in gosling growth in relation to variation in grazing pressure and food abundance because growth of goslings is directly linked to first-year survival, and consequently is the principal mechanism for density-dependent population regulation. Goslings grew substantially faster on the arctic coast and were nearly 30% larger than those on the Yukon-Kuskokwim Delta at four to five weeks old. Faster growth on the arctic coast was associated with 2× greater standing crop of C. subspathacea during brood rearing than on the Yukon-Kuskokwim Delta. Dispersal rates are high enough (Lindberg et al. 1998) to rule out local adaptation and genetic variation as explanations for observed variation in growth. Our results are consistent with lower survival of goslings from the Yukon-Kuskokwim Delta during their first fall migration and stronger density-dependent regulation on the Yukon-Kuskokwim Delta than on the Arctic coast.

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