Before sea-floor spreading:
* Mid-ocean ridges were seen as simple topographic features: They were thought to be volcanic chains formed by upwelling magma, but their significance in the Earth's overall system was unclear.
* The Earth was thought to be static: The idea of continents moving across the globe was controversial, and the origin of ocean basins was poorly understood.
After sea-floor spreading:
* Mid-ocean ridges became the sites of new crust creation: The discovery of magnetic striping patterns on the ocean floor provided compelling evidence for the spreading of the seafloor, with new crust being formed at the ridges and then moving away from them.
* Mid-ocean ridges became the key to understanding plate tectonics: The theory of sea-floor spreading explained the movement of continents, the formation of ocean basins, and the distribution of earthquakes and volcanoes.
* Mid-ocean ridges were recognized as dynamic features: The process of magma upwelling, cooling, and solidifying at the ridge creates new crust, which then slowly spreads apart.
* The age of the ocean floor became a key piece of evidence: The youngest oceanic crust was found at the ridges, while older crust was found farther away, confirming the continuous process of sea-floor spreading.
In summary:
The discovery of sea-floor spreading fundamentally changed our understanding of mid-ocean ridges. They transitioned from being passive features to being the key driving force behind plate tectonics, responsible for creating new oceanic crust and shaping the Earth's surface.
