Fish Creek drains an area of about 1.1 million acres (460,000 ha), entirely with the zone of continuous permafrost, and flows generally northeast for about 110 miles (177 km) through the Arctic Coastal Plain in the National Petroleum Reserve to Harrison Bay at the western edge of the Colville River delta, about 141 miles (230 km) southeast of Utqiaġvik and 12 miles (19 km) north-northwest of Nuiqsut, Alaska. The local name was first reported in 1951 by the U.S. Coast and Geodetic Survey. Harrison Bay is about 57 miles (92 km) across and situated on the coast of the Beaufort Sea between Cape Halkett to the west and Oliktok Point to the east. On July 26, 1837, Peter W. Dease and Thomas Simpson named the bay after Benjamin Harrison who at the time was deputy governor of the Hudson’s Bay Company. The Naval Petroleum Reserve Number 4 was created by President Warren G. Harding in 1923 during a time when the United States was converting its Navy to run on oil rather than coal. In 1976, the name was changed to the National Petroleum Reserve-Alaska, and in 1980, management authority to conduct oil and gas leasing was transferred to the Bureau of Land Management in the U.S. Department of the Interior. The oil-bearing sediments of the reserve occur primarily in sandstone bedrock which in the area of the Fish Creek delta is the Sagavanirktok Formation consisting of siltstone, shale, and sandstone with a maximum thickness of less than 525 feet (160 m). The bedrock is buried by extensive deltas of silt and sand with thick accumulations of frozen peat that formed at the mouths of the Colville River and Fish Creek since sea level reached its present elevation during the middle or late Holocene time. Permafrost is soil, rock, or sediment that has remained continuously frozen for more than two consecutive years. In areas not covered by ice, it exists beneath a layer of vegetation, peat, and soil that freezes and thaws annually. Winter temperatures cause soil to contract which forms cracks in the permafrost. In the spring and summer, melting snow and ice fills the cracks and freezes to form a wedge of ice. The mean annual air temperature needed to form ice wedges is −6° to −8° C or colder. Since water expands when it solidifies, the crack becomes enlarged with every freeze-thaw cycle. In time the ice wedges get so big that they push the material above into ridges that can be seen forming geometric shapes on the tundra.
The Iñupiat people of Utqiaġvik and Nuiqsut rely heavily on subsistence hunting and fishing. Depending on their location, they harvest walruses, seals, whales, polar bears, caribou, and fish. Along with other Inuit groups, the Iñupiat originate from the Thule people who migrated from islands in the Bering Sea around 300 BC. Their traditional territory includes lands north from Norton Sound on the Bering Sea to the Arctic Coastal Plain and east to the Mackenzie River. Historically there were many small settlements along the coast that were used by family groups as seasonal whaling and fishing camps. In 1837, Dease and Simpson were the first Europeans to explore this part of the Beaufort Sea coast when the Hudson’s Bay Company reached an agreement with the British Admiralty to survey and map the north coast and fill in gaps not mapped by John Franklin. They had sailed down the Mackenzie River in Canada and then westward past the Colville River Delta and reached a point a little beyond Cape Simpson, where they landed and proceeded west on foot to reach Point Barrow. Additional knowledge of the coast was gained from the various expeditions sent out between 1848 and 1853 to search for the missing party of Sir John Franklin. In 1849, Lieutenant William Pullen sailed in a small boat from Kotzebue Sound all the way around the Arctic coast to the Mackenzie River. Starting in the early 1900s, the U.S. Geological Survey sponsored many parties for exploration and geologic investigation of the Arctic coast, including William J. Peters and Frank C. Schraeder in 1901, and Ernest K. Leffingwell and Rudolph M. Anderson in 1906-1914. Further valuable contributions were made by Vilhjalmur Stefansson between 1908 and 1918. With the establishment of the Naval Petroleum Reserve by President Warren Harding in 1923, another series of investigations by the U.S. Geological Survey was begun at the request of the Navy Department. By the late 1940s, information from the field surveys provided a reasonably adequate, but still generalized, picture of the major geologic features of the reserve and the surrounding areas. Since the 1970s, oil and other mineral resources have become an important revenue source for the Iñupiat villages of the Arctic Coastal Plain and in many ways have introduced challenges to their culture and lifestyle exacerbated by the effects of climate change.
The coastal tundra in some areas is being inundated by rising sea levels. The topography along the Arctic Coastal Plain is very flat so small changes in sea level can inundate vast areas of low-lying tundra. A storm in 1970 generated a storm surge of 10 feet (3 m) that inundated a distance of 3 miles (5 km) inland, as evidenced by wood lines and salt-burned tundra. Increasing atmospheric and oceanic temperatures are accelerating coastal erosion of the Arctic Coastal Plain by decreasing the seasonal duration of sea ice, increasing the magnitude of storm surges, and increasing permafrost temperatures. The magnitude of storm surges over an ice-free Beaufort Sea not only drives coastal erosion but also dictates how storm surges develop that flood inland, salinizing lakes and impacting tundra habitat. Salt-burned tundra, as indicated by varying degrees of necrosis, can result from such storm surges. However, the types of vegetation susceptible to storm surges and the persistence of those effects are less certain. Coastal erosion and storm surge flooding also interact with changes occurring within the terrestrial permafrost environment such as progressive lake expansion due to thermokarst erosion and potentially lowering of land levels due to subsidence or deflation of ice-rich permafrost. The ridges surrounding tundra polygons at Fish Creek facilitate the ponding of water that exacerbates thawing and subsidence allowing more frequent flooding by the ocean. Thermokarst is a term used to describe the processes, landforms, and sediments associated with the loss of ice in permafrost by thawing. Thawing of permafrost reduces soil strength due to the change from a frozen to an unfrozen state and reduces soil volume due to the loss of excess ice resulting in ground subsidence. The degree of subsidence depends on the thickness of thawed soil and is most evident where it is localized, for example above intersecting ice wedges. The ice-rich soils and low relief of the Arctic Coastal Plain make vegetation highly sensitive to subsidence resulting from permafrost thaw. Saltwater inundation can kill typical tundra vegetation, and repeated inundation likewise increases thermal conductivity, potentially triggering more permafrost thaw and subsidence. Read more here and here. Explore more of the tundra polygons at the mouth of Fish Creek and Harrison Bay here:
