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Peter W. Barnes

Publications and source records attributed to Peter W. Barnes.

35 records · Page 2Linked to original sources
USGS1981

Ice-gouge data, Beaufort Sea, Alaska, 1972-1980

The interaction of sea ice with the sea floor is an important factor affecting geologic processes on high latitude shelves. One of the most obvious forms of this interaction is the formation of furrow-like gouges or the sea floor. These gouges are caused by wind- and current-driven ice masses that rake the seabed with their keels. Since the advent of side-scanning sonar about 1970, the morphology and character of these seabed features have been under study. Ice gouges have been reported from the Bering Sea (Thor and Nelson, 1980); from the Chukchi Sea (Rex, 1955; Toimil, 1978); from the Beaufort Sea off Alaska (Brooks, 1974; Carsola, 1954; Reimnitz et al., 1972); from the Beaufort Sea off Canada (Kindle, 1924; Lewis, 1978; Pelletier and Shearer, 1972; Wahlgren, 1979); from the east coast of Canada (Harris, 1974); from the northeast Atlantic (Belderson et al., 1973); and from the Great Lakes (Berkson and Clay, 1973).

Alaska↗
USGS1980

Dinkum Sands

The State/Federal Beaufort Sea lease sale in December 1979 attracted over one billion dollars in bids. Tracts with the highest bids, and apparently with the highest oil potential, lie in the area south of Dinkum Sands, and within a three-mile radius of the shoal (Fig. 1). Jurisdiction over the tracts within the three-mile radius depends on whether Dinkum Sands is an island, as shown by published charts and claimed by the State, or a mainly submerged shoal or bar as claimed by the U.S.G.S. If Dinkum Sands were an island, even the tracts halfway between the mainland and the island chain might be disputed as they then would be considered to form an enclave totally surrounded by State lands. Thus Dinkum Sands holds a strategic position within the lease sale area and, for the production life of the oil field, will be monitored at 5-minute intervals to provide a basis for division of the income from future oil production in that lease sale area.

Alaska↗
USGS1979

Fast-ice thickness and snow depth in relation to oil entrapment potential, Prudhoe Bay, Alaska

In winter, the undersurface of the sea ice on shallow arctic shelves acts upon the sea bed directly by contact and indirectly by influencing currents and turbulence. The under-ice surface would serve as a trap for pollutants such as oil and gas released from the sea bed. A knowledge of the morphology of the undersurface of the ice is a first step in understanding the sea-bed interactions and in evaluating the quantities, configuration, and dispersal patterns of sub-ice pollutants. Investigations show thicker sea-ice correlates with a thin snow cover and thin sea-ice underlies elongate snow ridges. In early May, 1978, the relationships between under-ice morphology, sea bed morphology, tidal currents, and variations in snow thickness were studied. At three sites representing three different environments--protected bay, deep, open lagoon, and narrow tidal channel--trenches were cut through the ice. The trenches were parallel and perpendicular to the sastrugi-sculptured northeast-southwest trending snow ridge pattern. Snow depth, ice thickness, and ice drafts were measured and an upward-directed side-scanning sonar was towed to examine the morphology of the under-ice surface in an area 100 m square. Snow depth and ice thickness vary about 30-40 cm and exhibit a negative correlation--thin ice coinciding with a thicker insulating snow cover. The areal snow and ice morphology patterns reinforced the correlation. Elongate ridge and trough patterns on the under-ice surface parallel the surface snow ridge patterns on wavelengths typically 10 m wide, yielding sub-ice voids of 25 to 47 x 10 3 m 3 /km 2 (600-1200 barrels per acre). Diving observations indicate a smaller set of depressions 5 cm or less in depth, oriented parallel to the ice crystal fabric, and an escape of sub-ice released air to the snow-ice interface. The results imply that there is a seasonal stability to the snow ridge pattern and that oil concentrations under the ice would be indicated by surficial snow morphology in the fast ice zone. Spreading directions would be enhanced in the elongate dimensions of the under-ice ridges and troughs, that is, upwind and downwind. In spring, gases will leak to the surface.

Alaska↗
USGS1979

Ice gouge obliteration and sediment redistribution event: 1977-1978, Beaufort Sea, Alaska

In 1978 major changes in shelf morphology were observed during a routine re-survey of part of the inner shelf region of the central Beaufort Sea. Regional observations are coupled with a detailed diving and side-scan study of a single ice gouge of known age to develop a detailed description of the altered seabed conditions. Hydrodynamic activity has caused extensive sediment reworking, obliterating ice gouges to water depths of at least 13 m and has caused ponding of sediment in ice gouge terrain in deeper waters. Ponded sediment is characterized as a soft, sometimes very poorly consolidated, mud unit underlain by a stiffer, more consolidated, silty clay. In places, stiff silty clay is exposed in windows in the sediment pond and displays a fine-textured ice gouge morphology. Rates of sediment reworking and redisposition from apparently episodic events are an order of magnitude greater than the average sediment accumulation rates on the Beaufort Sea shelf. Reported maximum ice gouge incision depths are not representative of maximum ice keel penetrations into the seabed because these sedimentation events preferentially infill gouges. Furthermore, because these sedimentation events concentrate sediments in gouge troughs, a series of overlapping and interfingering 'shoestring' deposits is developed which should characterize the ice gouge stratigraphy. The specific hydraulic mechanisms for sediment redistribution and sediment compaction observed in this study are only poorly understood.

Open-File Report↗
USGS1977

Bathymetric and shoreline changes, northwestern Prudhoe Bay, Alaska

The coastal environment in the vicinity of Prudhoe Bay, Alaska (Fig. 1) is presently being vigorously utilized by petroleum activities. In particular, barges moving freight onshore over the past 8 years, have used the Prudhoe Bay entrance channel almost exclusively. To further facilitate the offloading of supply barges, Atlantic Richfield Company constructed a gravel fill causeway in 1975 between the Prudhoe Bay channel and Stump Island (Fig. 1). As initially constructed, the causeway extended 1.3 km perpendicular to the coast. Subsequently the causeway was extended 1.5 km in a northwesterly direction during the winter of 1975-76 to facilitate the offloading of barges stranded during the fall of 1975.

Alaska↗
USGS1977

Distribution and character of naleds in northeastern Alaska

An examination of the distribution of river naleds seen in Landsat satellite imagery and high- and low-altitude aerial photography of Alaska's North Slope indicates that these features are widespread east of the Colville River and less abundant to the west. Where naleds occur, stream channels are wide and often form braided channels. Their distribution can be related to changes in stream gradient and to the occurrence of springs. Large naleds, such as on the Kongakut River, often remain through the summer melt season to form the nucleus of icing in the succeeding winter. Major naleds also are likely to significantly influence the nature of permafrost in their immediate vicinity. The map of naleds may serve as a guide to the occurrence of year-round flowing water, a sparse commodity in northern Alaska.

Open-File Report↗
USGS1973

Bottom features and processes related to drifting ice on the Arctic shelf, Alaska

Early investigations of artic shelf regions led to the hypothesis that certain micro-relief forms are related to the action of grounded ice (for example, Rex, 1955). Since the introduction of side-scan sonar as a tool for ocean-floor surveys, a number of workers have described the occurrence of linear bottom features produced by grounded ice. Such features have been found on modern polar shelves (Skinner, 1971; Pelletier and Shearer, 1972; Kovacs, 1972; Reimnitz and Barnes, 1972; Brooks, 1973), and as relict features (Berkson and Clay, 1973; Belderson and Wilson, 1973; Belderson and others, 1973). Studies of core samples, high resolution seismic profiles, and diving observations indicate that the sediments of the Beaufort Sea Shelf are highly distorted by the action of grounding ice, and that the recurrence rate of gouging is very high. It has also become evident that grounding ice is contributing considerably to the sediment transport processes of modern Arctic shelves. Sediments from similar environments exposed on the continents today should also contain the record of ice gouging and related processes. Thus it has become apparent that drifting ice is an important agent influencing the sedimentary structures and the sediment transport regime of Arctic shelves today and has been in the past. The diagrams presented here, with supporting evidence in the form of side-scan sonar records, and ice and bottom photos, demonstrate the most prevalent processes and types of bottom features observed on the continental shelf off northern Alaska. As the map shows, most of the shelf is affected by these processes today.

Alaska↗