Magnetic Stripes Hold Clues to Ocean Formation

"Several winters ago, a team of geophysicists from Missouri flew to the eastern edge of Africa, strapped on bulky backpacks and began walking. They were looking for a set of huge stripes in the Tendaho Graben, a place within the Afar Depression of Ethiopia, where Africa's continental crust is stretching thin and a new ocean will eventually form.

But the stripes they sought — and eventually found — aren't visible to the naked eye. They're magnetic stripes, similar to the ones lining the ocean floor at mid-ocean ridges. David Bridges, a geophysicist from the Missouri University of Science and Technology, and his colleagues sniffed them out using a bit of geological detective work, lots of walking and the hulking magnetometers strapped to their backpacks.

[Learn more about Ethiopia]

The Tendaho Graben's magnetic stripes are important because they're the first ones scientists have documented on land, Bridges said. Even more importantly, because these stripes have formed before the area becomes a water-covered basin, they may change the way researchers interpret the planet's oceans.

"The really interesting thing is that some of the oceanic basins may perhaps be a little bit younger than we currently believe," Bridges told OurAmazingPlanet.

Stripes and flips

The underwater relatives of Tendaho's magnetic stripes were first documented in the 1950s by geophysicists who set sail to take thousands of seaboard magnetic readings. The researchers eventually began to see that their readings sketched out distinct sets of stripes running parallel to mid-ocean ridges, and that each stripe's magnetic alignment was the reverse of neighboring stripes.

The striped magnetic pattern develops because, as oceanic crust pulls apart, magma rises to the surface at mid-ocean ridges and spills out to create new bands of ocean floor. Ferromagnetic minerals in the hot magma align themselves with the Earth's magnetic field, which completely reverses its north-to-south polarity every now and then, and freeze in that alignment as the magma cools. Later, after the planet's magnetic field flips again, the next stripe of new ocean floor aligns its polarity in the opposite direction.

"For many ocean basins, the timing of their openings has been based on the appearance of these magnetic stripes," because scientists long believed that the stripes first appeared when seafloor spreading started, Bridges said.

Tendaho breaks the trend

But the stripes that Bridges' team found in Tendaho may prove that conventional wisdom wrong.

Tendaho's magnetic bands, which measure 6 miles (10 kilometers) wide, are embedded in continental crust, not oceanic crust. And unlike magnetic stripes on the ocean floor, Tendaho's formed through diking: as the African crust stretched thin, streams of magma intruded the continental crust and hardened. Like in the oceanic stripes, ferromagnetic minerals in the dikes aligned with the planet's magnetic field as the magma hardened. Their magnetic signals are very similar to those of ocean-floor stripes.

This all happened sometime between 1.8 million years ago, when the region's continental crust began to break apart, and 780,000 years ago, when the Earth's magnetic poles last flipped, Bridges said.

Scientists predict it could be as many as 2 million years before the crust in the Tendaho Graben ruptures and begins to form an ocean basin. Altogether, this means that Tendaho's magnetic stripes could predate the future ocean basin by nearly 4 million years.

And magnetic stripes may predate other ocean basins, too.

"Other groups have found evidence suggesting that perhaps the Atlantic basin opened up a little later than what's currently believed," Bridges said. "It's sort of an interesting time in this field."

The team's findings appear in the March issue of the journal Geology.

Views: 19

Comment by Sam Guest on March 16, 2012 at 1:55am

 "perhaps the Atlantic basin opened up a little later than what's currently believed"


An intertesting statement considering the crisscrossing stripes they refer to are positioned in the exact location in the Atlantic that is purported to be the location of Atlantis. There are very old maps carved onto stones deep in the South American jungle that show North and South America and a third land mass in this exact location.


You need to be a member of Intl. Starseed Network to add comments!

Join Intl. Starseed Network


If ISN has helped you on your path to awakening and greater understanding...please consider a donation of your choice. Namaste

Calling All Florida Starseeds

Join Us At Earthdance 2016!

What's New?

peace2theworld replied to ♆ATHENA♆'s discussion im Having a baby?!
"science has been wrong 1000 times so far through history. seems this way science is not any better…"
16 minutes ago
peace2theworld replied to ♆ATHENA♆'s discussion im Having a baby?!
"personal evidence, vs verified with others evidence verifying by more persons does not make…"
22 minutes ago
peace2theworld replied to ♆ATHENA♆'s discussion im Having a baby?!
"maybe it is your definition of faith that is wrong faith does not need to be without evidene, it is…"
23 minutes ago
Eish Goldenheart commented on positiveevitisop's photo

Calm Night

"Poor granny smith had no idea what hit her."
48 minutes ago
Sinera Arenis replied to Abid's discussion Zarriah's Dicussion on TV
"I don't watch TV but I admit to watching some of the TV shows on streaming sites or…"
50 minutes ago
Angelic ~Star~Love ~ replied to ♆ATHENA♆'s discussion im Having a baby?!
"I have been following this post and it is indeed very insensitive what some people have commented…"
53 minutes ago
peace2theworld replied to ♆ATHENA♆'s discussion im Having a baby?!
"why would you keep your child a secret?? is there any reasoning behind this i would thin having a…"
1 hour ago
Sinh posted a discussion

A Simple Riddle

Riddle timeA great tree stands amidst a lush field. A lowly carpenter became enthralled by the…See More
1 hour ago
Sinh replied to ♆ATHENA♆'s discussion im Having a baby?!
""anyway the 144,000 are the starseeds, and you are all here as incarnated angels and…"
1 hour ago
peace2theworld replied to Abid's discussion Zarriah's Dicussion on TV
"don't watch tv.... if you absolutely must, be careful... subconscious programming, even in…"
1 hour ago
Jelly replied to Aamir's discussion My heart has been stripped of its rights.
"I do not try to help you, just giving you a method that you can learn and do it…"
1 hour ago
Shoreline loved Zarriah's discussion Anyone gave up television altogether??
1 hour ago

© 2016   Created by Yshatar.   Powered by

Badges  |  Report an Issue  |  Terms of Service