Why do oases exist in deserts?
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Answer: Groundwater reaches surface
Plants create moisture — Wrong. Plants don't create oases—water does! Oases form where groundwater springs reach the surface, allowing plants to grow.
Desert mirage effect — Wrong. Mirages are optical illusions. Oases are real—underground water reaching the surface through springs or shallow water tables.
Groundwater reaches surface ✓ — Correct! Oases form where underground water (aquifer) surfaces due to geological features—faults, impermeable rock layers, or depressions reaching the water table. Water from distant rain (sometimes mountains) travels underground and emerges, creating isolated fertile spots. Sahara oases sustained ancient trade routes!