Britannica
Sources used in this answer
How does seafloor spreading create submarine rift valleys?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
valley
The rugged Atlas Mountains surround a valley in Morocco.
Submarine rift valleys are formed at divergent plate boundaries, specifically along the crests of oceanic ridges where seafloor spreading occurs.12
The process involves the following geological mechanisms:
- Magma Upwelling: Molten magma from the Earth's mantle rises to the surface at the spreading center. As this material cools, it forms new oceanic crust.13
- Crustal Extension: As the plates diverge, the crust is subjected to tension, causing it to fracture. This extension leads to the formation of normal faults, where blocks of the crust (the hanging walls) slide downward relative to the surrounding rock.12
- Subsidence: The downward displacement of these crustal blocks creates an elongated, relatively flat-floored trough known as a rift valley.12
These valleys serve as the active zones where the seafloor is continuously pushed outward in both directions from the ridge crest, sustaining the growth of the ocean basin.14