Continental Drift:
* Focus: Explains the movement of continents across the Earth's surface over geological time.
* Mechanism: Proposed by Alfred Wegener in the early 20th century, but lacked a convincing mechanism for how continents could move.
* Evidence:
* Matching coastlines of continents.
* Fossil distribution across continents now separated by oceans.
* Similar rock types and geological formations on different continents.
Seafloor Spreading:
* Focus: Explains how new oceanic crust is created at mid-ocean ridges and spreads away from them.
* Mechanism: Based on the discovery of magnetic striping patterns on the ocean floor, which provide direct evidence of the process.
* Evidence:
* Mid-ocean ridges: Underwater mountain ranges where new crust is formed.
* Magnetic striping patterns: Symmetrical patterns of magnetic reversals recorded in the ocean floor.
* Age of the ocean floor: Older crust is found further from the mid-ocean ridges.
Relationship:
* Seafloor spreading is the *mechanism* that drives continental drift.
* The movement of oceanic plates caused by seafloor spreading pulls the continents along, resulting in their drift.
Summary:
* Continental drift is the *observation* of continents moving.
* Seafloor spreading is the *process* that causes the continents to move.
Think of it like this: Continental drift is like seeing a car moving down the road, while seafloor spreading is the engine that powers the car.
