begin quote from:
Tsunamis
waves tall enough to swallow the Statue of Liberty washed away the
shorelines of Mars’s ancient ocean, according to a study published
Thursday. In the wake of their destructive force, a Martian mystery was
born. …
Tsunamis waves tall enough to swallow the Statue of Liberty washed away the shorelines of Mars’s ancient ocean, according to a study published Thursday.
In the wake of their destructive force, a Martian mystery was born.
Planetary
scientists had hypothesized for decades that a primordial ocean might
have once covered much of the red planet’s northern hemisphere. Last
year they presented molecular traces of atmospheric water that backed the claim. But still missing from their theory were visible traces of the ocean’s coastline.
They essentially had evidence of an ancient ocean, but could not find its shore.
“We’re showing that the shorelines were there, but they were overrun and buried by the tsunami waves,” said J. Alexis Rodriguez, a Mars geologist at the Planetary Science Institute in Tucson, Ariz., and an author of the paper.
Using
images from spacecrafts orbiting Mars, Dr. Rodriguez and his colleagues
identified what they say are geological remnants like boulders and ice
debris left from the tsunamis. They published their results in the
journal Scientific Reports.
Dr.
Rodriguez said that some 3.4 billion years ago a meteor crashed into
the ocean triggering a mega-tsunami that plowed into the coast with
waves as tall as 400 feet. The meteor left behind a crater about 19
miles across. When the water retreated into the ocean it dropped 30-foot
tall rocks that obscured the original shoreline and also left behind
channels that provided clues to the ocean’s elevation.
Following
the event, the researchers think Mars then underwent a big freeze. At
which time the ocean’s top layer may have turned to ice like a lake in
winter.
Then
several millions of years after the first impact a second meteor
slammed into the ocean, generating a second mega-tsunami with waves as
strong as the first but made of an icy slurry, similar to a Canadian ice surge.
Unlike the previous tsunami, the second did not flow back into the
ocean after it ravaged the shore. Instead it froze, burying what was
left of the coastline.
He
compared the event with plunging a car into a pool filled with red
paint. The red paint would overflow and dry, masking the original
boundaries of the pool.
“We
reconciled this apparent contradiction that has been a major issue for a
long time between the proposed existence of an ocean and the apparent
absence of clear shoreline features,” he said.
Now,
Dr. Rodriguez and his team would like to see future rovers search the
tsunami scars in order to solve perhaps the biggest Martian mystery:
whether the planet once harbored life.
“It
gives us locations where we can investigate the primary composition of
the ocean,” Dr. Rodriguez said, “and determine if it was habitable or
not.”
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