The Hope Basin is a geological feature of the Chukchi Sea Shelf

Chukchi Sea Shelf

The Chukchi Sea Shelf or Chukchi Shelf is the easternmost part of the Continental shelf of Russia and the westernmost part of the Continental shelf of the United States...

. It lies off the Chukchi Sea

Chukchi Sea

Chukchi Sea is a marginal sea of the Arctic Ocean. It is bounded on the west by the De Long Strait, off Wrangel Island, and in the east by Point Barrow, Alaska, beyond which lies the Beaufort Sea. The Bering Strait forms its southernmost limit and connects it to the Bering Sea and the Pacific...

 coast of Alaska

Alaska

Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

. Its area extends from the outer continental shelf

Continental shelf

The continental shelf is the extended perimeter of each continent and associated coastal plain. Much of the shelf was exposed during glacial periods, but is now submerged under relatively shallow seas and gulfs, and was similarly submerged during other interglacial periods. The continental margin,...

 of the Seward Peninsula

Seward Peninsula

The Seward Peninsula is a large peninsula on the western coast of the U.S. state of Alaska. It projects about into the Bering Sea between Norton Sound, the Bering Strait, the Chukchi Sea, and Kotzebue Sound, just below the Arctic Circle...

 for about 700 km (435 mi) westwards off the coast of Chukotka

Chukotka Autonomous Okrug

Chukotka Autonomous Okrug , or Chukotka , is a federal subject of Russia located in the Russian Far East.Chukotka has a population of 53,824 according to the 2002 Census, and a surface area of . The principal town and the administrative center is Anadyr...

 towards Wrangel Island

Wrangel Island

Wrangel Island is an island in the Arctic Ocean, between the Chukchi Sea and East Siberian Sea. Wrangel Island lies astride the 180° meridian. The International Date Line is displaced eastwards at this latitude to avoid the island as well as the Chukchi Peninsula on the Russian mainland...

.

The Hope Basin is limited on its northeastern side by the Herald Arch (Herald Thrust), a basement uplift cored by Cretaceous

Cretaceous

The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

 thrust fault

Thrust fault

A thrust fault is a type of fault, or break in the Earth's crust across which there has been relative movement, in which rocks of lower stratigraphic position are pushed up and over higher strata. They are often recognized because they place older rocks above younger...

s. The Herald Arch is named after Herald Island

Herald Island (Arctic)

Herald Island or Gerald Island is a small, isolated Russian island in the Chukchi Sea, to the east of Wrangel Island. It rises in sheer cliffs, making it quite inaccessible, either by ship or by plane. The only sliver of shoreline is at its northwestern point, where the cliffs have crumbled into...

.

Type: Early Tertiary

Tertiary

The Tertiary is a deprecated term for a geologic period 65 million to 2.6 million years ago. The Tertiary covered the time span between the superseded Secondary period and the Quaternary...

 extensional

Extensional tectonics

Extensional tectonics is concerned with the structures formed, and the tectonic processes associated with, the stretching of the crust or lithosphere.-Deformation styles:...

 basin

Basin (geology)

A structural basin is a large-scale structural formation of rock strata formed by tectonic warping of previously flat lying strata. Structural basins are geological depressions, and are the inverse of domes. Some elongated structural basins are also known as synclines...

(mainly).