Iran’s Rainbow Island


A mix of uplifting salt and other sedimentary and metamorphic rocks make for colorful landscapes in the Persian Gulf.

With its colorful soils, salt caves and mountains, and ocher-stained streams and beaches, Iran’s Hormuz island is rich with memorable geology.

The island is a salt dome—a teardrop-shaped mound of rock salt, gypsum, anhydrite, and other evaporites that has risen upward through overlying layers of rock. Rock salt, or halite, is weak and buoyant, so it loses its brittleness and flows more like a liquid when under high pressure.

The rising mass is not purely made of salt. Embedded within it are layers of clay, carbonates, shale, and iron-rich volcanic rocks, some of which have taken on vivid shades of red, yellow, and orange as they moved upward and interacted with water and minerals from other rock layers.

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Image via NASA Earth Observatory