The Bridge River Ocean between North America and the Insular and Omineca volcanic arcs
The Insular Islands were an extended chain of volcanic islands forming an arc in what is now the Pacific Ocean during the Paleozoic and Mesozoic eras. The islands formed by subduction and melting of the Farallon Plate along a fragment (or microplate) upon which they rose called the Insular Plate. They were bounded by the Panthalassic Ocean to the west and the Bridge River Ocean to the east. They probably formed as a composite of several volcanic chains near the equator, offshore of continental landmasses, by the Carboniferous Period around 300-325 million years ago.
Geologic belts of far-western Canada and Southeast Alaska, including the Insular Belt (red)
The chain continually moved northward during the Mesozoic. About 115 million years ago in the mid-Cretaceous they finally collided with and fused onto the North American Plate. Like the earlier Intermontane Islands which underwent a similar continental accretion 60 million years before, the large mass of the islands preventing them from being pushed under the North American Plate. This violent collision halted subduction which fed volcanic activity in the Omineca Arc and closed the Bridge River Ocean. The subduction zone moved westward to the Farallon Trench, causing new volcanism which formed the Coast Range Arc.
Rocks of the Insular Islands now comprise wide sections of the westernmost coast of the North American plate. This includes both the Insular Mountains of the Alaskan Panhandle, Haida Gwaii, and Vancouver Island, and sunken areas of the greater Insular Belt which takes into consideration rock formed on the floor of the Bridge River Ocean. This extends to the northern North Cascades range in Washington State, perhaps as far as the Wallowa Mountains in northeastern Oregon which may be a displaced fragment from the Insular Belt. The "suture" at the former continental margin is now a major northwest-trending fault through the North Cascades, the 10 kilometers wide, 500 kilometer long Ross Lake Fault.[1]
^"The Coast Range Episode". The Burke Museum of Natural History and Culture. Retrieved 1 January 2010.
The Insular Government of the Philippine Islands (Spanish: Islas Filipinas Estadounidenses) was an unincorporated territory of the United States that was...
The InsularIslands were an extended chain of volcanic islands forming an arc in what is now the Pacific Ocean during the Paleozoic and Mesozoic eras....
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Island gigantism, or insular gigantism, is a biological phenomenon in which the size of an animal species isolated on an island increases dramatically...
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(Pacific, extension of Hawaiian Islands) Ile Du Sud- African Banks (in the Amirantes) InsularIslands, Pacific Intermontane Islands, Pacific Majority of granitic...
volcanic islands approached a pre-existing continental margin and coastline of North America. These volcanic islands, known as the InsularIslands by geoscientists...
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Insular Italy (Italian: Italia insulare or just Isole, lit. 'Islands') is one of the five official statistical regions of Italy used by the National Institute...
was a broad coastal plain. The Insular Mountains formed when a chain of active volcanic islands (the InsularIslands) collided against the North American...
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Insular Chile, also called Las islas Esporádicas, or "the Sporadic Islands", is a scattered group of oceanic islands of volcanic origin located in the...
notable islands of the United States, including its insular areas, which are listed at the end. Mormon Island (Colorado River) Arbuckle Island Sentinel...
The Islands of Tokyo (東京諸島, Tokyo-shotō), also known as the Insular Area of Tokyo Metropolis (東京都島嶼部, Tōkyō-to-tōshobu) or Izu-Ogasawara islands (伊豆・小笠原諸島...
late as 1979. The term "insular" signifies that the territories were islands administered by the War Department's Bureau of Insular Affairs. Today, the categorizations...
responsible for the outlying insular areas including American Samoa, Guam, the U.S. Virgin Islands, and the Northern Mariana Islands. Insular area Compact of Free...
Ocean was an ancient ocean that existed between North America and the InsularIslands during the Mesozoic era. Similar to the earlier Slide Mountain Ocean...
Cretaceous period. The Insular Plate had a chain of active volcanic islands that were called the InsularIslands. These volcanic islands, however, collided...
Island syndrome describes the differences in morphology, ecology, physiology and behaviour of insular species compared to their continental counterparts...
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one of the four islands are administered, along with its surrounding minor islands and islets, by an insular council (consell insular in Catalan) of the...
island gray fox, Channel Islands fox, Channel Islands gray fox, California Channel Islands fox and insular gray fox. The island fox is significantly smaller...
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Retrieved July 9, 2013. "Virgin Islands". The World Factbook. Retrieved July 9, 2013. "Baker Island". Office of Insular Affairs. Archived from the original...
including U.S. States, the national capital of Washington, D.C., insular areas, and outlying islands. Links to more detailed state lists are shown. As of 2020...
but informally (and ambiguously) as the Pine Islands, is the name given collectively to the Balearic Islands of Ibiza (Catalan: Eivissa), Formentera, S'Espalmador...
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