<p>The elevation of oceanic crust is controlled by Pratt <a href="https://en.wikipedia.org/wiki/Isostasy" rel="noreferrer">isostasy</a>, whereby hotter crust is elevated because it is less dense. Oceanic crust is produced at mid-ocean ridges and cools as it moves away from the ridge. <strong>Mid-ocean ridges are hot and therefore they are elevated above the colder, more dense adjacent crust.</strong></p>

<p>In continental rifts, the dominant process controlling the topography is <a href="https://en.wikipedia.org/wiki/Extensional_fault" rel="noreferrer">normal faulting</a>, which leads to subsidence of the rift valley floor and uplift of the sides, leading to the formation of mountains either side of the active rift. <strong>Continental rifts form valleys because they have not yet reached isostatic equilbrium and their topography is controlled by extensional faulting.</strong></p>

CC BY-SA 3.0
2018-01-28T21:21:52.627Z
2018-01-28T21:21:52.627Z
bon
<p>Why Divergent boundary create ridges between oceanic plates and rift valley between continental plates? I think that the ridges are formed because of the volcanic eruptions. But like rift valley in case of continental plates, can trench ever form because of the divergent oceanic plates?</p>

<plate-tectonics><continental-rifting><ocean-ridge>
Divergent boundary and trenches between oceanic plates
Porcupine
# Divergent boundary and trenches between oceanic plates

(Asked by: username_0 on 2018-01-28)

Why Divergent boundary create ridges between oceanic plates and rift valley between continental plates? I think that the ridges are formed because of the volcanic eruptions. But like rift valley in case of continental plates, can trench ever form because of the divergent oceanic plates?

**Tags:** plate-tectonics, continental-rifting, ocean-ridge


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## 1 answers

### Answer by username_1 on 2018-01-28. Score: 5

The elevation of oceanic crust is controlled by Pratt [isostasy](https://en.wikipedia.org/wiki/Isostasy), whereby hotter crust is elevated because it is less dense. Oceanic crust is produced at mid-ocean ridges and cools as it moves away from the ridge. **Mid-ocean ridges are hot and therefore they are elevated above the colder, more dense adjacent crust.**

In continental rifts, the dominant process controlling the topography is [normal faulting](https://en.wikipedia.org/wiki/Extensional_fault), which leads to subsidence of the rift valley floor and uplift of the sides, leading to the formation of mountains either side of the active rift. **Continental rifts form valleys because they have not yet reached isostatic equilbrium and their topography is controlled by extensional faulting.**


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