gen-define-plate-tectonics-and-give-one-short-worked-example-9102

Define plate tectonics and give one short worked example.

# Plate Tectonics **Definition:** Plate tectonics is the scientific theory that Earth's outer shell (lithosphere) is divided into several large, rigid plates that move slowly over the underlying, more fluid asthenosphere. These movements cause earthquakes, volcanic activity, mountain building, and ocean trench formation at plate boundaries. ## Worked Example: The Himalayan Mountains **Scenario:** The Indian Plate colliding with the Eurasian Plate **Process:** 1. **Initial condition:** ~50 million years ago, the Indian Plate moved northward at ~15 cm/year 2. **Collision:** Indian Plate meets Eurasian Plate (both continental, low density) 3. **Result:** Neither plate subducts; instead, they crumple and push upward 4. **Calculation:** - Distance traveled: 15 cm/year × 50 million years = 7,500 km - Uplift created: The Himalayas, with Mt. Everest at 8,849 m - Ongoing rise: ~5 mm/year currently **Evidence:** Fossils of marine organisms found at high elevations in the Himalayas confirm this region was once an ocean floor (Tethys Sea) that was thrust upward by plate convergence. This exemplifies a **convergent boundary** where plates move toward each other.