Where in the world can you walk on exposed mantle rock from the middle of the earth? Where can you hold rocks that are 500 million years old?
Answer: You can hike on rocks, which should be beneath the ocean floor, in Gros Morne National Park on the Great Northern Peninsula of Western Newfoundland.
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| Tablelands hiking trail sign |
| Photo © Barb & Ron Kroll |
How to get to the Tablelands
Although visitors can drive the 704 kilometers (437 miles) from St. John's to Gros Morne in 10 hours, we traveled to the national park on an Adventure Canada cruise around Newfoundland. Our ship docked at the wharf in the town of Woody Point on the southern shore of Bonne Bay, a deep inlet off the Gulf of St. Lawrence.
The Gros Morne Discovery Centre is only a 30-minute walk from the wharf. A shuttle bus brought cruise passengers from the Discovery Centre along Route 431 to the trailhead parking lot for the Tablelands walk.
Walking Trail
The Tablelands are on a plateau that rises 700 meters (2,300 feet) above the Atlantic Ocean. This ocher rock-covered moonscape spreads between the South Arm of Bonne Bay and Trout River Pond.
The length of the Tablelands Trail is only four kilometers (2.5 miles). It is an easy hike along the flat Old Mill Road Trail, over crushed rocks and a few boardwalks. Visitors can download a free Explora app for a self-guided tour from the Gros Morne National Park website.
Guided hike
Our Tablelands walk was 1.5 hours long, including the return trip. Even though it was June, we dressed warmly because there were no trees or obstructions to block the wind.
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| Hikers walk on Tablelands Trail past mantle rock from below an ancient ocean floor |
| Photo © Barb & Ron Kroll |
Penny McIsaac was our enthusiastic Parks Canada guide. Her informative, often humorous, explanations made it easy to understand how the rocks around us were thrust up by massive collisions of tectonic plates.
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| Photographing yellow peridotite rocks |
| Photo © Barb & Ron Kroll |
Continental drift
Using two volunteers from our group, she moved one (representing the ancient continent of North America, called Laurentia) toward the other (representing Gondwana, the ancient land mass of what would become Africa, South America and Antarctica). "Between them was the Iapetus Ocean," she said.
"When Gondwana collided with Laurentia, lots of rocks were pushed up and the ocean disappeared, forming the new continent of Pangaea."
As she moved the second person back, she continued her explanation. "Gondwana receded, creating the continents of North America, Europe and Africa, with the Atlantic Ocean between them."
Inside our planet
Penny McIsaac encouraged us to pick up and examine one of the yellow, dusty rocks at our feet. Why is the rock on the Tablelands yellow, while the rest of Gros Morne National Park is lush and green? Exposed to the atmosphere, the iron in the rock is oxidizing to rust.
Holding an apple in her hand, she explained that the skin represented the earth's crust, which is made up of continental plates floating on the mantle. "Here on the Tablelands, as a result of repeated collisions and opening and closing of oceans, we have mantle rock on top of the earth's surface."
Why can we see this mantle rock today? "Glaciers exposed it. They also carved out the Bonne Bay fjord," she said.
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| Broken-open peridotite with black-dark green center |
| Photo © Barb & Ron Kroll |
Appearance of mantle rock
Penny told us that the mantle rock was peridotite. "It contains heavy metals—cobalt, iron, magnesium, nickel, chromium and peridot." (When it's gem quality, this olive-green mineral, called olivine, is made into birthstones.)
Looking around, she pointed out a hunk of peridotite that was freshly broken. It was easy to see its dark green interior.
Rock that looks like serpent skin
"Why do some rocks resemble snake skin?" asked one hiker. "The rock with white lines all over it is called serpentine," said Penny.
"It's a metamorphic version of peridotite," she explained. "Because it is no longer under the earth's crust, oxygen, heat and water extract calcium from the rock to form the white lines on the surface."
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| Serpentine rock |
| Photo © Barb & Ron Kroll |
Tablelands plants
The barren, desolate Tablelands look like they should be devoid of life, but Penny showed us a surprising amount of vegetation during our hike.
"Plants that grow on the Tablelands are similar to those that grow in the Arctic," she explained. "Because the soil is not hospitable, they develop adaptations to survive in a difficult landscape."
We noted that most of the plants were very tiny, so that they lose less heat and are less exposed to the elements.
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| Serpentine sandwort |
| Photo © Barb & Ron Kroll |
Wildflower survival adaptions
Penny pointed out a little mound of moss campion (Silene acaulis) with brilliant pink flowers. "It has a single strong root, like a carrot, that can grow down two meters (six feet) to find water.
"These little white flowers belong to the serpentine sandwort (Minuartia marcescens)," she said. "It likes toxic soil and needs heavy metals to survive, so it accumulates nickel."
Near a patch of snow, we spotted a sea thrift (Armeria maritima) blossom, blowing in the wind atop a tall stem. It also likes poor soil.
Revived with water
We walked to a patch of grey wool moss that resembled a sheep's fleece coat. "It is white because it's dormant," she said. "We call it dead sheep wool."
She pulled out a bottle and squirted water on the moss. It turned green. "When it rains, the plant knows it is safe to photosynthesize."
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| Parks Canada guide, Penny McIsaac, with photo of Newfoundland's provincial flower behind pitcher plant |
| Photo © Barb & Ron Kroll |
Insectivorous plant
"Beware! We are among carnivorous plants," joked Penny. She positioned a photo of Newfoundland and Labrador's floral emblem behind a pitcher plant (Sarracenia purpurea) so we could see the red wine-colored flower that blooms in mid-July.
"It's passive carnivorous," she explained. "The pitcher plant has slimy, wet leaves and it smells delicious, like cheese, so bugs say yum! The insects slip inside and can't climb out."
What do pitcher plants eat?
Penny McIsaac told us that pitcher plants don't secrete digestive enzymes, so they need helpers to decompose trapped insects. "Midge flies need an aquatic environment to lay their eggs. Their larvae feed on the insects and their excrement feeds the pitcher plants. So, the provincial flower of Newfoundland and Labrador eats poo!" she concluded, with a wide grin.
Penny used pipettes to suck up some of the water inside the tubular pitcher plant leaves and handed us the pipettes. What did we see inside the liquid? White larvae and some very sad insects!
The Tablelands have two other insectivorous plants, including the round-leaved sundew (Drosera rotundifolia) and the common butterworth (Pinguicula vulgaris), but because of their smaller sizes, they get less attention.
We asked why carnivorous plants grow in Gros Morne's Tablelands. "They're not growing in good soil, so they need nutrients from insects to survive," responded Penny.
Winterhouse Brook Canyon
We continued our hike on Tablelands Trail to Winterhouse Brook Canyon, an alpine glacial valley in a classic U-shape. As we stood on a railed lookout platform above a stream gushing over rocks, Penny told us about the beautiful guided hikes to the top of the Tablelands from this canyon.
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| Hikers stand on Winterhouse Brook Canyon lookout in Gros Morne National Park |
| Photo © Barb & Ron Kroll |
"The top," she said, "is a fen system, where you can see greater yellow legs (birds). The vegetation is thin, but it holds the water."
She explained that NASA sends astronauts here to learn how to move around boulders. The rocks produce methane and researchers are studying them to see if they can create organic material from inorganic.
UNESCO World Heritage Site
As we retraced our steps back to the starting point for our hike, we now understood why the Tablelands look like an alien landscape. Because it is. A half billion years ago, the exposed mantle rocks around us came from deep inside the earth, 10 kilometers (six miles) below the ocean's crust.
These yellow rocks provided geologists with evidence that continents move. For this reason (as well as for the beauty of its volcanic coastline, Western Brook Pond and other scenic landscapes), UNESCO designated Gros Morne National Park as a World Heritage Site in 1987.
TRAVEL INFORMATION
Gros Morne National Park
Newfoundland and Labrador Tourism
Adventure Canada
More things to see & do on Adventure Canada Newfoundland Circumnavigation cruises:
L'Anse aux Meadows UNESCO Site Tour - Visitor Center, Trail and Sod Huts
Lookout Trail Hike - Gros Morne National Park Newfoundland
Fogo Island Newfoundland - Brimstone Head Trail Hike
Francois NL Hiking - Charlie's Head, The Friar and Pond Trails
St. John's Newfoundland - Pre/Post Cruise Tours
