Heat From Green Rock
The towers of Lost City were able to grow so tall in part because they are nine miles away from the volcanic vents of the Mid-Atlantic Ridge. This distance buffers the rocks from volcanic eruptions that occur once every five to ten years at the ridge's axis and from earthquake activity that's more frequent around the vents.
But their distance from the underwater vents also suggests that the towers must be formed by a unique process.
In so-called "black smoker" formations, ocean water sloshes near hot magma at the volcanic vents and then heats up to 750 degrees Fahrenheit. The hot water absorbs minerals and chemicals from surrounding rocks and eventually flows upwards. As the hot water rises, it cools and releases the minerals and chemicals, which form towers of dark mineral rock and nutrient-rich ecosystems.
In Lost City, the construction of the stone towers appears to be driven not by hot magma but by a rare rock. Sections of a glassy green rock known as olivine are exposed directly under small cracks in the ocean floor. When ocean water seeps into this 1.5-million-year-old mantel rock, it reacts with the olivine to form a scaly, dull green rock known as serpentine.
This reaction generates heat, which triggers the same building of mineral deposits as seen at black smokers. But the deposits at this site are made of a different, paler rock.
"The fluids coming out of these cracks at Lost City have not been found before," said Karen Von Damm of the Institute for the Study of Earth, Oceans and Space at the University of New Hampshire. "So it's likely there's also new life there that hasn't been found before."
By "new" life, Von Damm means undiscovered life that may be very ancient. Some people believe any life around the chalky towers of Lost City may resemble the earliest life-forms on Earth.
Like Primitive Earth?
Unusual life-forms called Archaea have been found around traditional oceanic vent systems. These animals have been placed near the bottom of the evolutionary time scale. Scientists believe any life-forms near Lost City might be even more primitive.
Any animals living near Lost City would exist in temperatures of about 160 degrees Fahrenheit—below the scorching temperatures of other hydrothermal vents and closer to what is thought to have been the early climate of Earth. The new vents also have high pH levels, or low acidity, which some scientists believe also may have been present when life began on the planet.
The site also produces high levels of methane, which the most ancient forms of bacteria are thought to have feasted on billions of years ago.
"The area conjures up the origins of life," said Richard Lutz, an oceanographer at Rutgers University who, in the late 1970s, was among the first oceanographers to explore the first hydrothermal vent system ever discovered. "There's a good case that this could have been the kind of environment where life began."