Rock Star Bob

Mars-like, except for the boardwalk!
Mars-like, except for the boardwalk!

No, not Bob Dylan. Or Bob Seeger. We’re talking about Bob Stevens.

When “Light my Fire” topped the charts in the summer of 1967, a twenty-two-year-old Brit, a geologist named Bob Stevens who had answered a newspaper ad posted by Newfoundland’s Memorial University four years earlier, made a discovery in the province’s Tablelands. 

Bob found pieces of peridotite. 

This was a highly unusual discovery—peridotite is crystallized magma from the earth’s mantle. 

How did peridotite, from 10 kilometers below the ocean crust, surface in Newfoundland? 

Bob was the first person to find the answer, to recognize and establish the mechanism and detailed timing of tectonics in Newfoundland that led to the confirmation of plate tectonic theory, which until then had only been hypothetical. Bob concluded, as published in Worldwide Quest, that

…the Tablelands are a rare Ophiolite complex– a section of the Earth’s oceanic crust and the underlying upper mantle that, instead of being pushed down in a subduction zone, was pushed up onto continental crustal rocks. The Tablelands are the remnants of ancient ocean floor, the Iapetus Ocean, that existed five hundred million years ago.

When plates collide, the denser oceanic plate is forced to dive under the continental plate, a process called subduction. But when two continental plates collide, enormous blocks of trapped seafloor can be thrust onto the continental margins, a process called obduction.

As we understand it, when the ancient supercontinent of Rodinia broke apart, a rift formed and filled with water known as the Iapetus Ocean (named for the father of Atlas in Greek mythology), forming two continents, Gondwana and Laurentia. As the new continent of Pangea began to develop, the land plates reversed direction. About 485 million years ago, the Iapetus Ocean closed, and the land plates smashed against each other, upheaving a fragment of the earth’s mantle and oceanic crust to form the Tablelands. It remained buried until after the last Ice Age 12,000 years ago.

Said to have been a modest man (we could find only one photo of him), Bob discussed his findings, but didn’t publish them until 1970. Subsequently, geologists in New England reclaimed his ideas and garnered most of the credit.

How important is the scientific theory of plate tectonics? Scientists say:

What the Galápagos is to biology, Gros Morne National Park is to geology.

What Einstein’s relativity theory is to physics, plate tectonic theory is to geology.

Bob’s discovery ultimately led to the Tablelands becoming a UNESCO World Heritage Site in 1987 and, eight years later, Gros Morne becoming a national park.

On a May afternoon, we and about sixty other people set foot on two-billion-year-old rocks for a walk on “the soul of the earth.”

I always thought peridotite was green, yet the landscape here is mostly a dull bronze. Turns out peridotite contains iron, which when exposed to oxygen for thousands of years, turns a rusty brown.

Snow cover prohibited hiking to the table top, so Magellan and I lingered around the bubbling springs and tiny waterfalls. 

Then, just off the main trail, we found the most exciting thing at Tablelands—large boulders of peridotite with snakeskin-like patterns. Called serpentine rocks, the scientific name for for these exposed pieces of mantle is ophiolite, from the Greek words ophio (snake) and lithos (stone). 

More than pretty, they’re also very rare. 

There’s little vegetation in this desert-like landscape because of the high concentration of toxic minerals in magma rock. We hadn’t thought of it being Mars-like until we saw a full-page photo in The Globe & Mail from the province’s tourist board with the words,

“And to think some people are trying to get to Mars”

Scientists were shocked to find the bubbling water we’d been photographing is full of microbial life. The microbes feed on carbon monoxide and other poisonous elements in an underground process called serpentinization that occurs when water reacts with rocks from the earth’s mantle. Scientists are using the Tablelands as a test site to determine the habitability of other areas of serpentinization—like Mars.

On the advice of Ruth Ann and Bruce, we went to the Johnson Geo Centre in St. John’s, which has a wonderful display on plate tectonics that outlines the contributions of Bob and other scientists from Memorial University and elsewhere. Foolishly, we didn’t take our cameras. 

With all the musical talent in Newfoundland, maybe someone, someday, will write a song about Rock Star Bob. “Walk, walk, walkin’ on earth’s deep floor…”

Navigation

Cobb, Quentin: Geology in Newfoundland’s Tablelands Worldwide Quest.

McCormick, Lucie. “Where you can see the ‘soul’ of the Earth.” BBC. Nov 12, 2020.

Morrill, Penny L.; Szponar, Natalie; Brazelton, William J.; Schrenk, Matthew O.; Bower, Dina M.; and Steele Andrew. “The Tablelands Ophiolite of Newfoundland: A Mars analogue site of present-day serpentinization.” Analog Sites for Mars Missions. 2011. 

SIAAT. “Advancing the Plate Tectonics Model. Robert Keith Stevens 1939-2014.”

10 Responses

  1. Today, before reading your blog, we just returned from hiking in the Tablelands. Incredibly beautiful and no snow where we were. We are spending our second night in Woody Point before heading up the Great Northern Peninsula. Great place to visit.
    Wendy and Pat

  2. No doubt “The Rock” is an interesting display of geology for the world to see. It’s location alone screams of upheaval from generations past, the visits by yearly iceberg’s tells us the world of change is a constant visitor to this area. Throw in the ocean currents and seasonal storms and you have the ideal world to create ongoing change.
    Gros Morne is “Mother Natures” display to assist in our ongoing thirst for education and knowledge, May it ever be there for future generations.
    Nice story. 👍👍👍👍👍

    1. Outstandingly creative and informative, the province’s tourism board has a new story feature created by travellers to the province. Check it out for more on “The Rock.”

    1. Probably not much different a million years from now. But expect big changes within 5 million years. The East African Rift is slowly tearing Africa, and may eventually open up an ocean basin, like the Red Sea, and then later to something much larger, like a small version of the Atlantic Ocean.

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