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New Ocean being Formed in Africa
PenguinRadio writes "The San Francisco Chronicle is reporting on a 37-mile long fissure that split open in September in the Afar desert in Ethiopia that could be the start of a new ocean forming. The fissure, which grew 8 meters wide in 3 weeks following an earthquake on Sept 14, is now splitting at about 0.8 inches per year, would eventually lead to Ethiopia eastern portions becoming an island in a million years or so. The findings were presented at the American Geophysical Union meeting taking place in San Francisco this week. The BBC reports that formation of a ocean basin is the first step toward developing an ocean, but that it will be millions of years before that could occur."
BBC article
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(from Slashdot) Science: New Ocean Being Formed in Africa
(from BBC NEWS) Geologists Witness 'Ocean Birth'
And then explaining that really it MAY be the birth of an Ocean, or MAY be a big rift that will settle down.
Fortunately, doing a bit of research shows that it's just lazy reporting, as many people with detailed knowledge of Geology have been aware of this "triple-junction" of plates, and the events that tend to indicate that the some of the plates will start moving away from each other. For those with a more graphical mind http://pubs.usgs.gov/publications/text/East_Afric
My complaint is in how poorly this thing was headlined. It's overselling the news. A giant rift widening is exciting enough, and the article can then speculate that it could become an ocean. If it's generally believed that this rift's becoming an ocean is a foregone conclusion, then there's no need for the disclaimer about rifts stabilizing.
The disclaimer is silly. There's little liability for getting a prediction wrong when the results are projected to be apparent in a million years. It does nothing but weaken the article, muddling the facts with a bunch of posits until you can't determine if this is news or hyperbole.
The Afar region has been stretching apart, in the process of forming a new ocean, for the last 10 or 20 million years. Stretching rates in various parts of the rift vary from 6 to 12mm per year. Parts of the Afar region are already >100m below sea level and filled with salt deposits, and the area is faulted extensively, with many tilted blocks of older material and extensive volcanoes (e.g., Erte Ale) related to the stretching (imagine the effect if you stretched a piece of candy with a brittle crust). So, the headline isn't really news at all.
The new part is the establishment and growth of such an obvious fissure where one did not exist before. The new one is fascinating, but only the latest example of a process that has been ongoing for a long time, and which will probably continue for millions of years more before the ocean eventually invades.
So let me get this straight. There was an earthquake that opened a crack in the earth three months ago and now the scientists involved can tell, after only three months that there will be a sustained widening of this crack by less than one inch per year. After one million years of this exact widening of one inch a year there will be a new ocean created.
Maybe it is hjust me but most real scientific fact going out a million years would likely be based on more than a three month snapshot of data.
The Afar area is a triple junction where upwelling magma is driving 3 continental crust apart - the Arabian plate, West Africa and East Africa. The plates crack in 120 deg pieces because the configuration relieves plate extensional stress with minimal displacement. What typically happens when the basin expands is that one of arms is abandoned, again for thermodynamic reasons. Spreading along a single great circle requires less membrane deformation of the outer crust than spreading along 3. The principle of least action at work. In this case the active arms of the triple junction are the Red Sea and the East Indian ocean which are sites of rapid spreading of oceanic crust. Th East Africa Rift is clearly spread more slowly than the active arms and will fail. The North Sea, Mississipi delta, Camaroon rift, Connecticut Valley, etc are examples of rift valleys and failed arm abandonment during the opening of ocean basins. Sure, volcanism and rifting can still occur in the failed arm. The extensional faults that define these areas assures this. We see this in Afar, and deeper in the African rift. Camaroon is another example. The triple function there opened 120 Mya and it is still active. But is will never form a wide ocean basin. Afar tectonics are still a very interesting phenomen.
an ill wind that blows no good
After seeing others get grants, I think I want to go back to university and get a Ph.D. in sociology. I'll do my Ph.D. on the effects of having a million dollar trust fund and driving a ferrari. Now I just need to fill out that application for the grant.
Within the past couple of years the rate of acceptance for NSF proposals has dipped to as low as 2-3%. Recently, I heard that their new goal is to increase their acceptance rate to a whopping 5%. Also, do not totally buy into the belief that peer-review leads to pure merit-based grant awards; there is still a whopping "who you know" factor.
Good luck in your new career!
http://www.volcano.si.edu/world/volcano.cfm?vnum=0 201-113&volpage=var
Speaking as an amateur geologist, I think I can safely use the geophysical jargon and say, "MAN that is FREAKY!"
that, my friend, is the entire punchline. It is pointing out the ridiculous nature of the assumption that the earth was created in any timespan measured in thousands of years.
The term "ocean" when used by an Earth Scientist has a specific meaning which isn't quite the same as the common, everyday usage meaning a large expanse of water.
Geologically, an ocean is a region of the Earth's crust composed of basaltic rocks (of MORB composition) which is generated at a spreading ridge. Because the thickness of this type of crust is pretty uniformly 15Km thick, it's somewhat lower than sea level, hence the expanse of water. This is very different from continental crust which is granitic in composition, far less dense and usualy greater than 30Km thick.
You can get ocean-like spreading ridges elsewhere, one type of these being certain back-arc basins. Although they are look very similar, because of the different composition of the basalt, they are not considered to be oceans.
Now, the term "lake" is generally used to describe a body of fresh water which is laying on a continent. A sea (which isn't really a scientific term at all) is generally ocean water washing over a continental basin which is often surrounded by large islands or other land masses.
The term "land" is not really that scientific a term either, merely meaning the common term for the part of the Earth's surface not covered with water.
I hope this has helped to clarify this for you. The (over) simplification of scientific subject by journalists is a constant bain for scientists in all fields of study.
Agrajag: "Oh no, not again!"