[Rockhounds] Deep Beneath Earth’s Surface, Clues to Life’s Origins

[Kreigh Tomaszewski]

Near midnight on March 26, 1961, dark waters lapped at the hull of a
converted naval barge as it queasily rocked in the Pacific Ocean. The ship
had just arrived at this spot, some 240 kilometers off the Baja peninsula,
after three days of fighting seas so rough the crew had lashed gear to the
deck with heavy chains, “like a rogue elephant,” the novelist John
Steinbeck, who was aboard the vessel, later wrote for *Life* magazine
<https://books.google.com/books?id=9lEEAAAAMBAJ&pg=PA110#v=onepage&q&f=false>
.

Back on shore, rumors flew about the crew’s goals. Some speculated that
they were hunting for diamonds or sunken treasure. Others suspected that
they were scouting for a place to stash a missile on the seafloor. But the
team’s objectives were even loftier than the wildest hearsay. The plan —
hatched over an alcohol-infused breakfast at the La Jolla home of the
geologist Walter Munk — was to drill a hole so deep it would punch through
Earth’s crust and reach the planet’s mantle, a hot, rocky layer sandwiched
between Earth’s crust and its core.

Now, more than 62 years after the effort known as Project Mohole,
scientists still have yet to successfully drill through an intact section
of Earth’s crust. But this past spring, a team aboard the decades-old
drillship the *JOIDES Resolution* accomplished the next-best thing: They
retrieved a trove of mantle rocks from an area of the Atlantic seafloor
where the crust is especially thin. The site is atop a submarine mountain
known as Atlantis Massif, where the slow shifts of tectonic plates have
shoved blocks of mantle rocks closer to the surface.

While the mantle makes up the bulk of our planet, its rocks are usually
buried kilometers beneath the surface, making fresh samples tough to
retrieve. But mantle rocks such as those excavated last spring could offer
clues to the deep workings of Earth and help researchers better understand
the tectonic choreography that’s fundamental to our world.

The newly collected rocks may also hold clues to another defining feature
of our planet — life.

https://www.quantamagazine.org/deep-beneath-earths-surface-clues-to-lifes-origins-20240104/