1. Upwelling Magma: As the plates pull apart, the pressure on the underlying mantle decreases. This allows hot, molten rock (magma) to rise up from the mantle.
2. Mid-Ocean Ridge Formation: The upwelling magma erupts and cools, forming new oceanic crust. This process builds up a long, underwater mountain range known as a mid-ocean ridge.
3. Seafloor Spreading: As more magma erupts and cools, the new crust pushes the older crust away from the ridge, causing the seafloor to spread. This movement can be measured in centimeters per year.
4. Formation of Rift Valleys: At the very center of the divergent plate boundary, the plates are pulling apart so rapidly that a deep valley known as a rift valley can form.
5. Other Features:
* Hydrothermal Vents: These are hot springs that release mineral-rich water into the ocean. They support unique ecosystems.
* Volcanic Islands: If magma rises above sea level, it can form volcanic islands along the mid-ocean ridge.
Consequences of Oceanic Divergence:
* Creation of New Oceanic Crust: This process continuously adds new crust to the Earth's surface.
* Expansion of Ocean Basins: As the seafloor spreads, ocean basins become wider.
* Formation of Mid-Ocean Ridges: These ridges are a key feature of the Earth's tectonic plates.
* Creation of Unique Ecosystems: Hydrothermal vents support diverse communities of organisms that thrive in extreme conditions.
Examples of Oceanic Divergence:
* Mid-Atlantic Ridge: Separates the North American and Eurasian plates, as well as the South American and African plates.
* East Pacific Rise: Separates the Pacific and Nazca plates.
* Iceland: A volcanic island formed by divergence between the North American and Eurasian plates.
