1.3 Origin and Evolution of the Earth’s Crust

Case Study 1: Formation of the Himalayas

• Relevant Theories/Models: Plate Tectonics Theory; Continental Collision Model, Catastrophic Model, Non-Catastrophic Model
• Recent Data: The Indian Plate continues to move northward at approximately 5 cm/year, colliding with the Eurasian Plate. This ongoing convergence has led to the uplift of the Himalayas over the past 50 million years.
• Spatial Variation: The rate of uplift varies across the Himalayan range, with some regions experiencing uplift rates of up to 10 mm/year.
• Temporal Variation: The collision began around 50 million years ago, marking the closure of the Tethys Sea and initiating the Himalayan orogeny.
• Source: USGS; The New Indian Express
• Insight: The Himalayas exemplify the dynamic nature of Earth’s crust, showcasing the processes of plate convergence, crustal shortening, and mountain building.

Case Study 2: Deccan Traps and the Breakup of Gondwana

• Relevant Theories/Models: Continental Drift Theory; Mantle Plume Hypothesis
• Recent Data: The Deccan Traps, covering over 500,000 square kilometers, were formed due to extensive volcanic activity around 66 million years ago, coinciding with the breakup of the supercontinent Gondwana.
• Spatial Variation: The basaltic flows are predominantly found in western and central India, with thickness varying across regions.
• Temporal Variation: The main phase of volcanic activity occurred over a period of less than 1 million years, indicating rapid crustal evolution.
• Source: Geological Survey of India; ScienceDirect
• Insight: The Deccan Traps illustrate the role of mantle plumes and continental drift in the evolution of Earth’s crust, contributing to significant climatic and biological events, including the mass extinction at the Cretaceous-Paleogene boundary.