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Originally posted by gazerstar
Wow! This is fascinating! Thanks for the heads up. If it doesn't fill up with ocean, Africa may have their very own Grand Canyon some day.
This is probably a stupid question, but is it possible that if water does enter into the 'canyon' that it could come up from underground like from an underground caving system, or is that even possible due to its location?
Originally posted by Solenki
reply to post by kiwifoot
Since i've been reading ATS I've always read some crazy things about geology, and being a geologist is almost heartbreaking.
1. Stop with the expending earth... with enough time i'll demonstrate you why it's impossible, and proof of the earth being a whole solid body but well, it's already late here (i'm in france), so maybe next time.
2. about the rifting :
first, you have to have a source of heat juste beneath the crust. This source of heat is generally a magma plume, comming up because of archimed's law and will induce a diminution in the crust thickness. Just like if you were melting a layer of plastic from beneath.
then Volcanism appears, is our case, this is the nexte step commine ahead.
After volcanism, extenstion makes it's move, this is when the rifting really occur.
Then, you began to have a separation, this is the full rifting process, each border of the rift are separating, creating normal faults and the crust keep getting thinner.
As the borders or lips, of the rift are separating, a sedimentary basin is being created, and sediments beguns to accumulate.
this accumulation will add a weigh on rocks, creating Subsidence (search it!), basically, the basin will sink because of the weight and because of the heat (this is how you create petroleum, by getting rich organic matter rocks deeper, and you know that deeper you are, hotter it is, so organic matter can be cracked into hydrocarbures).
Then, as the bottom of the rift is getting deeper, it will pass under the Mean Sea Level, so, water will flood it creating a sea.
Next step, if the extension goes on, you will have an ocean. End of the story.
the way the crust is getting thinner will be the main setting to know if the rift will pursue is opening or not.
We calcul a shortening factor (beta) with the lenght of the crust, if this factor is less than a certain number, rifting will not continue.
3. So yeah, having a rifting will modify the sea level, we call it "tectono-eustatisme" here in France, don't know how to say it in english, sorry guys.
Being simple, as you modify the basin configuration, you will have an effect on the mean sea level.
By the way you can also modify the volume of the ocean...
How ? simply by activating the oceanics rifts, you will then create more oceanic crust thus you change the volume of ocean, more volume for the same amout of water = decreasing sea levels.
For the one wondering why rifting is usually observed in deep sea, juste remeber that rifting always begins into the continent, then lead to the formation of a sea, and then at last to the formation of an ocean.
Search for Wilson Cycle, you will understand how it works globaly.
Finally, for those still giving the old propaganda of the hollow earth and the earth in expansion, please, read some more about plate tectonics, subduction, collision and wilson cycle. I just can stand those people, they are creationist for me. No offence, it's juste that all the creastionist I've encountered were narrow minded about scientific fact.
I hope my explaination was clear, sorry I do what I can in english and I'm in a kind of hurry to go sleeping at last.
Don't hestitate if you have questions, I may not be the best geologist, but I can surely help understand.
bye ATS I love reading you before sleeping !
Originally posted by Anamnesis
If I may add some things to help clarify the original post.
The Ethiopian Desert Rift which appeared in 2005 is merely another in a series of rifts that have occured along the East African continent that together are known as the East African Rift (Great Rift Valley). The rift(s) are caused by the divergent Nubian and Somalian sub-plates. Some of the deepest lakes in the world are located along the rift zone (Lake Tanganyika - 1,470 metres deep)
"The East African Rift, which traverses it beginning with the southern end of the Red Sea, going through Eritrea, Ethiopia, Kenya, Tanzania and Mozambique."
This geological event has been in progress for millions of years and will likely take another million or so before the Red Sea eventually floods the rift valley(s) becoming a new sea.