1.7 Continental Drift

Case Study 1: Gondwana Breakup and the Indian Plate Drift

• Models/Theories/Laws:
  • Wegener’s Continental Drift Theory (1912)
  • Paleomagnetism Evidence
  • Plate Tectonics and Hotspot Tracks (Deccan Traps)
• Recent Data:
  • ISRO and NGRI confirm Indian Plate moving northward at ~5 cm/year.
  • Recent paleoclimatic data from Antarctica and India reveal similar fossil flora (Glossopteris) and coal deposits—evidence for Gondwana.
  • Satellite gravimetry (GRACE Mission, 2024) shows isostatic adjustments post-drift.
• Spatial Variation:
  • Drift Path: From ~30°S latitude (Permian) to current ~20–30°N.
  • Formation of Deccan Traps due to passage over Réunion hotspot ~66 MYA.
• Temporal Variation:
  • Breakup began ~180 MYA (Jurassic), Indian plate drifted rapidly (~15–20 cm/year) between 120–50 MYA.
  • Slowed upon collision with Eurasia (~50 MYA).
• Source:
  • PIB: “India's Geodynamic Monitoring Network” (2024)
  • DownToEarth: “Tracking India’s Plate Movements” (Oct 2023)
  • Science Journal (2023): “Hotspot Tracks and Indian Plate Velocity”
  • National Geographic Atlas of Plate Movements (2023)
• Insight:
  • Continental drift theory is validated by India’s paleo-positioning, fossil correlations, hotspot tracks, and rapid northward drift, forming a base for modern plate tectonic reconstructions.

Case Study 2: Atlantic Ocean Formation and Drift of South America and Africa

• Models/Theories/Laws:
  • Fit of Continents (Wegener)
  • Magnetic Stripes on Ocean Floor (Seafloor Spreading by Hess)
  • Wilson Cycle of Ocean Basin Evolution
• Recent Data:
  • South America-Africa divergence rate: ~2.5 cm/year (NOAA, 2023)
  • Symmetrical magnetic anomalies on the Mid-Atlantic Ridge (MAR) observed using ARGO floats and marine magnetometers.
  • Fossil matches (Mesosaurus, Glossopteris) reaffirm drift.
• Spatial Variation:
  • Maximum ridge spreading observed near the equator (~3 cm/year)
  • Slower spreading toward poles (~2 cm/year)
• Temporal Variation:
  • Initial rifting during Late Jurassic (~170 MYA), major oceanic crust formation ~130 MYA
  • Continues to present with MAR volcanism
• Source:
  • NOAA Ocean Explorer Reports (2023)
  • Frontiers in Earth Science (2024): “Atlantic Ridge Morphodynamics”
  • Yojana (Feb 2024): “Ocean Floor and Global Dynamics”
  • Philosophical Transactions of the Royal Society B (2023)
• Insight:
  • Atlantic Ocean evolution offers textbook evidence for continental drift, with real-time ridge spreading, fossil correlation, and geophysical validation of Wegener's foundational ideas.