1. Increasing Age and Thickness:
* Age: The lithosphere created at the ridge is initially hot and buoyant. As it moves away, it cools and becomes denser. This means the farther from the ridge, the older the lithosphere.
* Thickness: As the lithosphere cools, it contracts and thickens. This is due to the addition of new lithospheric material from the mantle and the loss of heat.
2. Increasing Depth:
* The denser, older lithosphere sinks deeper into the mantle, resulting in an increasingly deep ocean floor. This is why ocean trenches, which mark subduction zones, are generally located far from mid-ocean ridges.
3. Sediment Accumulation:
* Over time, sediments from rivers, wind, and biological activity settle on the ocean floor. The thicker the lithosphere, the longer it has been exposed to sediment deposition, resulting in a thicker layer of sediment.
4. Subduction (at Convergent Plate Boundaries):
* Eventually, the dense, older lithosphere may reach a subduction zone, where it is pushed beneath a less dense plate. This process leads to volcanic activity, earthquakes, and the formation of mountain ranges on the overriding plate.
In summary, as oceanic lithosphere moves away from a mid-ocean ridge:
* It ages and thickens.
* It becomes denser and sinks deeper.
* It accumulates more sediment.
* It may eventually be subducted at a convergent plate boundary.
