Motion between the Kula Plate and the North American Platealong the margin of the Bering Shelf (in the Bering Sea north of the Aleutian arc) ended in the early Eocene. The Aleutian Basin, the ocean floor north of the Aleutian

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The islands, known before 1867 as the Catherine Archipelago, include six groups (east to west)
• the

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The climate of the islands is oceanic, with moderate and fairly uniform temperatures and heavy rainfall. Fogs are almost constant. Summer weather is much cooler than Southeast Alaska

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The growing season lasts approximately 135 days, from early in May until late in September, but agriculture is limited to the raising of few vegetables. With the exception of some stunted

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On the less mountainous islands, the raising of sheep and reindeer was once believed to be practicable. There are bisonon islands near Sand Point. Sheep raising seems to have died off

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In addition to a partial air service and a ferry service, the Alaska Marine Highway passes through many of the U.S. islands.

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The Aleutians are home to many large colonies of seabirds. Buldir Island has 21 breeding seabird species, including the Bering Sea-endemic

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