Nunivak
- Terra MODIS
- 04 June 2001
- 22:57 UTC
At 4,226 km² in area, Nunivak is the second-largest island in the Bering Sea after Saint Lawrence and is the 8th largest island of the United States. The island is located off the southwestern coast of the Alaskan mainland, lying 29 km across the Etolin Strait, opposite the kangirlvar Bay region of the coastal Nelson Island — itself part of the Yukon-Kuskokwim Delta (the mouth of the Kuskokwim River is visible in the panoramic image). In the above image Nelson Island's snow-tipped Cape Vancouver and kangirlvar Bay are both visible in the upper-right corner.
From Cape Corwin in the east to Ikook Point (at the tip of Cape Mohican) in the west, Nunivak has a maximum length of 110 km. North to south the island has a maximum width of 67 km (Cape Etolin to Cape Mendenhall).
Nunivak presents a tundra-like landscape that sits atop an upland plateau averaging 160 m above sea level. The plateau (snow-covered in the above image) occupies much of the island's interior. The plateau is volcanic in origin — Nunivak is essentially a group of ancient shield volcanoes. Signs of past volcanism are evident throughout the upland regions of the island: There are some 60 volcanic cones that break the relief of the plateau, including Ikathiwik Crater (214 m), Ingrilukat-Naskorat Hill (286 m), Seemalik Butte (264 m), Kikikyak Hill (233 m) and the island's highest peak of Roberts Mountain (511 m).
Four lake-filled maar formations (a low relief crater caused by a phreatic eruption) are also found on Nunivak (Ahkiwiksnuk, Binalik, Nanwaksjiak, and one unnamed maar). The floors of both the Ahkiwiksnuk and Nanwaksjiak maars descend through the plateau to sea level. There are also numerous, short, basaltic lava flows on the island, most measuring less than 3 km in length.
Volcanic activity on Nunivak is thought to have occurred during a number of distinct phases, separated by long periods of quiescence, between 6 million years ago to several thousand years ago, that slowly moved eastwards across the island.
From the interior plateau the terrain drops to a broad, gently sloping, coastal belt that receives the many streams and rivers that flow off the uplands. Like the interior, the coastal belt is studded with hundreds of small lakes. The northern and southern shorelines of Nunivak present a contrast in features. The north is characterised — particularly the northwestern side — by rocky coastlines, promontories, steep volcanic cliffs and small offshore islets. The southern coast of Nunivak, in contrast with that of the north, is lined by a series of coastal lagoons, sandy beaches, marshland and a few areas of steep slopes, rocks and low cliffs.
The most dramatic features of the southern coast are the long, sweeping, stretches of coast that lie directly either side of the Cape Mendenhall peninsula. These sections of the coast are backed by tall dunes systems — the Nunathloogagamiutbingoi Dunes on the east, and the Bangookbit and Bangookthleet Dunes on the west.
Much of Nunivak is protected as part of the Yukon Delta National Wildlife Refuge, administered by the U.S. Fish and Wildlife Service; the southern sector of the island is a designated Wilderness Area.
image: MODIS rapid response project at nasa/goddard space flight center
