Beaufort Sea
Our editors will review what you’ve submitted and determine whether to revise the article.
Beaufort Sea, outlying sea of theArctic Ocean situated north ofCanada andAlaska. It extends northeastward fromPoint Barrow, Alaska, toward Lands End on Prince Patrick Island, and westward from Banks Island to theChukchi Sea. Its surface area is about 184,000 sq mi (476,000 sq km). The average depth is 3,239 ft (1,004 m) and the greatest depth 15,360 ft. It is named for the British rear admiral Sir Francis Beaufort.
Thecontinental shelf is narrow, especially near and east of Point Barrow; it widens somewhat north of theMackenzie River mouth but nowhereexceeds 90 mi (145 km). The usual depth is less than 210 ft, although the slope descends steeply to 5,000 or 6,500 ft in the sea’s upper part. Small gravel islands or shallows are often found. The largest islands are west of the Mackenzie River mouth—Herschel (7 sq mi) andBarter (5 sq mi). Very small islands and banks are found in the Mackenzie River Delta.
Thecontinental slope of the sea is cut by numerous submarine valleys. The Beaufort plateau, with depths from 6,500 to 10,000 ft, protrudes far into the sea, west of Banks Island. The geological structure of the bottom is that of a massive platform, and seismicdata indicate a similarity between the crust of the Canadian Basin and of the oceans.
The coasts along the Beaufort Sea are low-lying and almost entirely covered withtundra. Only west of the Mackenzie River’s mouth do spurs of theBrooks Range approach the coastline.Banks andPrince Patrick islands are also fairly low, maximum elevations being from about 900 to 2,450 ft.
The Beaufort Sea is under ice almost the year round; only in August and September does the ice break up, and then only near the coasts. Four water masses may be distinguished. The surfacewater mass is nearly 330 ft thick and ranges in temperature from 29.5° F (-1.4° C) in late summer to 28.8° F (-1.8° C) in winter. Thesubsurface water mass, formed by the waters of thePacific Ocean and the Bering Sea flowing through theBering Strait, is much warmer than the surface water and almost reaches theNorth Pole. The deepAtlantic water is the warmest of all, its temperature ranging from 32° to 34° F (0° to 1° C). Thebottom water has temperatures ranging from 30.6° to 31.3° F (-0.4° to -0.8° C).
The direction of the surface and subsurface currents is closely related to the general current system of the Arctic Ocean. A clockwise water gyre flows north of the Beaufort Sea; the majority of the sea’s currents are thus westward or southwestward. Only in thevicinity of the mouth of the Mackenzie River is an eastward current recorded.
The Mackenzie River deposits about 15 million tons of sedimentary material annually into the sea, including high concentrations ofdolomite andcalcium carbonate, which are found at great distances from theriver delta. Gravel, pebble, and sand deposits, sometimes mixed with mud, are widely distributed on the continental shelf underlying the sea.
More than 70phytoplankton species are found in the Beaufort Sea, but the total biomass is not large. Nearly 80zooplankton species have been found, and the bottom fauna consists of nearly 700 species of polychaetes, bryozoans, crustaceans, and mollusks.
The chief settlement along the Beaufort Sea isPrudhoe Bay, Alaska, which is the centre ofpetroleum production on the coastal lowland known as the North Slope. TheTrans-Alaska Pipeline carriescrude oil south from Prudhoe Bay toValdez, an ice-free port almost 800 miles (1,300 km) away on Alaska’s southern coast. Fishing and sea hunting along the Beaufort Sea are for local supply only.