Clarifying Confusing Concepts: Strait and Isthmus: A Strait is a Narrow Body of Water

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Isthmus Versus Straits: Clarifying Confusing Concepts | Geography
Strait and Isthmus
  • A strait is a narrow body of water that connects two larger bodies of water. It may be formed by a fracture in an isthmus, a narrow body of land that connects two bodies of water. Tectonic shifts can lead to straits like this.
  • An isthmus is a narrow strip of land that connects two larger landmasses and separates two bodies of water. This type of isthmus is called a tombolo, and is formed as waves and tides slowly build up a sand bar to create a permanent link between a coastal island (called a tied island) and the mainland.
Tectonic Activity is the Strait of Gibraltar
  • One strait that was formed by tectonic activity is the Strait of Gibraltar, the only link between the Mediterranean Sea and the Atlantic Ocean.
  • The Strait of Gibraltar is narrowing and closing, as the African plate slides north. Soon, Strait of Gibraltar will be the Isthmus of Gibraltar, and the Mediterranean will be a large, salty, inland sea. If fractures in an isthmus are created by human activity, the straits are usually called canals.
  • Suez Canal was constructed in 1869 as a waterway between the Mediterranean Sea and the Red Sea
  • A strait can also be formed by a body of water overflowing land that has subsided or has been eroded. The Bosporus, which links the Black Sea and the Marmara Sea, was formed this way – separates Europe from Asia
  • The Isthmus of Panama in Panama links the continents of North and South America
  • The Isthmus of Suez in eastern Egypt connects the continents of Africa and Asia, and separates the Mediterranean and Red Seas.
The City of Seattle, Washington
The City of Seattle, Washington
  • The city of Seattle, Washington, is located on an isthmus between the Puget Sound (part of the Pacific Ocean) and Lake Washington.
  • Mount Maunganui, New Zealand, is a tombolo town located on a sandbar connecting the volcanic island of Mauao to the mainland.