16

Rifting is an ongoing process. At the moment, e.g. East Africa is rifting apart from the Nubian plate, we also see rifting of continental plates elsewhere, eg Rio Grande. New continents are being formed, but it doesn't happen on a human time scale. Modellers of future geography have a difficult task to decide what rifts that will stop and what rift that ...


14

The oceanic plates are themselves formed from the divergent boundary, so probably not. Even if a new rifting occurred exactly at the boundary, the result would eventually be that the ocean floor surrounds the divergent boundary. A very simplified model of an ocean would have a divergent boundary in the middle. This oceanic spreading center might have ...


7

Assuming that the surface density is relatively constant, it would be impossible to have all of the above water land mass concentrated on one side of the Earth. That's a bad assumption. Four key differences between oceanic and continental crust are Chemical composition. The rock that forms oceanic crust has more calcium and magnesium but less aluminum and ...


6

Your intuition is quite correct: Other factors being equall, a dense magma will not rise through lighter rocks. The exception is if it is under pressure, in which case a fluid magma will escape through 'pressure release' pathways, either laterally or vertically (or in complex geologic structures, in a variety of irregular pathways). Magmas may begin to ...


5

The elevation of oceanic crust is controlled by Pratt 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 ...


4

To clarify: Your question is valid, although if you are referring to Dr. von Frese's words as paraphrased in this article, you may be conflating a potential "breakup initiation" with something like the "creation of a geologically weak area prone to rifting under extensional stress". I believe the thought that such a crater could have caused the beginnings ...


4

As the continental crust is too buoyant (light) to be subducted, when two continents collide they smash against each other creating a mountain range, in this case the Himalayas. This process happen trough thrusting and folding of the plates, leading to something called lithospheric shortening. Which basically means that the plates (lithosphere is the stuff ...


2

OK. Let's assume, for the sake of argument, that oceanic and continental crust does have the same density (it doesn't, but that doesn't matter). Let's further assume that everything under the earth's crust has constant density (it doesn't, but that also doesn't matter) To a first approximation, the oceans will form a surface of constant distance from the ...


1

You May think of this situation as following: Consider an ocean-ocean divergent boundary and one of the oceanic plates (OP) is subducting below the continental plate (CP). Following shows such a setting. <----(OP)----|(MOR)|----(OP)---->\\ <----CP---- where, OP= Oceanic Plate. MOR= Mid Oceanic Ridge. CP= Continental Plate \ \ = shows subduction ...


1

The origin of continental crust is from the differentiation of Earth, where silicates rose to form the mantle and even lighter silicates rose, then cooled, to form the crust of early cratons. Not quite. The lighter silica rich rocks that compose the continental crust form by partial melting of pre-existing denser basaltic rocks. When you partially melt ...


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