Bathymetric Evidence for Seafloor Spreading

Bathymetric Evidence for Seafloor Spreading

The ocean floor is not flat it has mountains, valleys, and ridges that provide clues about how Earth’s surface changes. Bathymetry is the study of the ocean floor’s depth and shape. Scientists have used sonar and satellite imaging to map the ocean floor, revealing mid-ocean ridges, deep trenches, and rift valleys. These features provide strong evidence for seafloor spreading, a process where new oceanic crust forms at mid-ocean ridges and moves outward. Understanding bathymetric evidence helps scientists study plate tectonics, earthquakes, and the formation of new oceanic crust.

Science and Engineering Practices (SEP): Developing and Using Models

Scientists use models to study seafloor spreading by analyzing bathymetric maps, sonar data, and GPS measurements. These models help show how tectonic plates move, how new crust forms, and how old crust is recycled into the mantle. Scientists also create 3D models of mid-ocean ridges to understand how magma rises and forms new rock, pushing older rock away.

Activity Ideas:

• Bathymetry Box Model – Use a shoebox, string, and a ruler to simulate how scientists measure ocean depth. Poke holes in the lid and measure the depth of objects inside to create a depth profile, just like a sonar reading.
• Seafloor Spreading Map Lab – Examine a simplified bathymetric map showing mid-ocean ridges and trenches. Use string or paper strips to measure distances from the ridge and analyze how the depth and age of the seafloor change as you move away from the ridge.

Crosscutting Concepts (CCC): Patterns

Patterns in bathymetric maps provide strong evidence that the ocean floor is constantly changing due to seafloor spreading.

• Pattern: The ocean floor has mid-ocean ridges, where new crust forms, and trenches, where old crust is destroyed.
  • Example: The Mid-Atlantic Ridge is a giant underwater mountain range where magma rises and forms new seafloor.
• Pattern: The depth of the ocean floor changes in predictable ways, with ridges in the middle and deep trenches near continents.
  • Example: The Mariana Trench is the deepest part of the ocean, formed when the oceanic crust sinks beneath another plate.
• Pattern: The age of the ocean floor increases as you move away from mid-ocean ridges.
  • Example: Rock samples from the Atlantic Ocean floor show that the youngest rocks are near the Mid-Atlantic Ridge, while older rocks are found closer to the continents.