In News:

A recent study published in Global and Planetary Change (2025) has uncovered 117-million-year-old mud waves buried nearly 1 km beneath the Atlantic seabed west of Guinea-Bissau. This finding reshapes our understanding of the formation of the Atlantic Ocean, ancient climate patterns, and tectonic shifts during the Cretaceous period.

About Mud Waves

• Definition: Large, rhythmic sedimentary structures formed on the seafloor by persistent bottom currents.
• Age & Size: Approximately 117 million years old; over 1 km long and several hundred meters high.
• Location: Deep seabed, west of Guinea-Bissau, near the Equatorial Atlantic Gateway.
• Composition: Layered sediments preserving evidence of historic ocean circulation.

Formation Process

1. Early Atlantic Spillover: Around 117 million years ago, the young North Atlantic Ocean began spilling dense, salty waters into southern basins through the newly formed Equatorial Atlantic Gateway.
2. Underwater Avalanches: The influx collided with older, stagnant waters rich in mud and organic matter, triggering massive sediment avalanches.
3. Wave Formation: These currents pushed and piled up sediments into wave-like structures, which solidified into permanent mud waves over millions of years.

Scientific Significance

• Rewrites Ocean History: Suggests Atlantic waters circulated much earlier than previously thought.
• Climate Insights: Provides evidence of Cretaceous climate shifts and ancient carbon cycles.
• Tectonic Implications: Offers clues to plate movements shaping Earth’s geography during the breakup of Gondwana.

About the Atlantic Ocean

• Size & Shape: Second-largest ocean after the Pacific; distinctive ‘S’-shape.
• Major Features:
  • Mid-Atlantic Ridge: 14,000 km long, ~4 km high, central seafloor mountain range.
  • Continental Shelves: Widest along NE America and NW Europe.
  • Islands & Seamounts: Azores, Canary Islands, Bermuda, Cape Verde.
  • Trenches: Puerto Rico Trench, Romanche Trench (less prominent than Pacific trenches).
  • Marginal Seas: Hudson Bay, Gulf of Mexico, Baltic Sea.