Magnetic Reversals
and
Evolutionary Leaps

Massive asphalt domes found on sea floor  
Erupting oil paved the seafloor with mysterious mounds

26 Apr 10  - Some 700 feet deep and about 10 miles off the coast
from Santa Barbara, sits a group of huge volcanic domes unlike any
other underwater features ever seen.

"They're larger than a football-field long and as tall as a six-story building," said lead researcher David Valentine, a geoscientist at the University of California, Santa Barbara (UCSB). "They're massive features, and are made completely out of asphalt."

The asphalt formed when petroleum flowed from the seafloor some 30,000 to 40,000 years ago. (I wonder if this might date to a magnetic reversal.)

There are seven such domes. "The largest we called Il Duomo," said Valentine.  

"It was an amazing experience, driving along ... and all of a sudden, this mountain is staring you in the face," said Woods Hole Oceanographic Institution (WHOI) director Christopher M. Reddy,
who said the dome was teeming with undersea life."

Using the submersible robot Alvin, Valentine and Reddy broke off samples and brought them to labs at UCSB and WHOI for testing.
 

WHOI scientist Chris Reddy (left) and UCSB scientist Dave         Valentine with a large sample of rock from Il Duomo. They         could heft it easily because it was made of asphalt, the         solidified residue of oil.         (Molly Redmond, University of California, Santa Barbara)

The volcanoes underscore a little-known fact, said Reddy, a marine chemist. "Half the oil that enters the coastal environment is from natural oil seeps like the ones off the coast of California."  

 

A few asphalt-like undersea structures have been reported, says Valentine, "but not anything exactly like these…no large structures like we see here." He estimates that the dome structures contain about 100,000 tons of residual asphalt.

We brought a big sample back from the seafloor, as big as Dave and I., said Reddy. I’ll never forget that we picked it up off the deck and held it. Had this been cement or rock or marble, we would have been Charles Atlas or Arnold Schwarzenegger times 10.

Though the volcanoes have been dormant for thousands of years, the dive revealed a few spots where gas was still bubbling.

The researchers reported their findings April 25, 2010, in the journal Nature Geoscience.