All landmasses on Earth are constantly shifting and rearranging. The British Isles most likely just broke off as all landmasses do at one point or another. However, during the Ice Age (for example), the British Isles and Europe were connected due to the low sea levels. But once the ice melted, sea levels rose and the land bridge disappeared.
Italy is separated from the rest of Europe by the Alps.
The Alps separate Russia from the rest of Europe.
Poland, Czechoslovakia, Hungary, and Yugoslavia separated the Soviet Union from Western Europe.
The Atlantic Ocean separated the USA from the war in Europe.
Europe and Asia
Europe is not in North America. Europe and North America is separated by the vastness of the Atlantic Ocean.
Asia
America and Europe
The Pyrenees Mountains have kept Spain separated from Europe for much of history. They're on the border of France and Spain.
Morocco is the African country separated from Europe by the Strait of Gibraltar, which connects the Atlantic Ocean to the Mediterranean Sea.
Eastern North America and Western Europe are separated by the Atlanic Ocean. Northern Europe and the northern part of North America are separated by the Arctic Ocean.
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