The Tablelands: Walking on the Earth’s Mantle

Drive south from Woody Point in Gros Morne National Park and the landscape changes in the space of a few minutes. Green, forested fjord country gives way to a wide, bare massif the colour of rust. No trees. Almost no plants. Loose rock running up to a flat summit plateau under a sky that suddenly feels bigger than it did a kilometre back.

Most people’s first reaction is that it looks like another planet. The more accurate description is stranger than that: it looks like the inside of this one.

What You Are Actually Standing On

The Tablelands are made largely of peridotite, the rock that forms the Earth’s upper mantle. Normally it sits many kilometres below the crust, well out of reach. Here it is at the surface, under your boots.

It got there through plate tectonics. Roughly 485 million years ago, an ancient ocean called the Iapetus was closing as the continents that would later form Pangaea converged. In the collision, a slab of ocean floor and the mantle beneath it was forced up and pushed onto the edge of the ancient North American continent. Geologists call this kind of displaced slab an ophiolite, and the Tablelands are among the clearest examples exposed anywhere on Earth. They are a large part of the reason Gros Morne is a UNESCO World Heritage Site.

For geologists, this is the textbook case: a place where the theory of plate tectonics stops being a diagram and becomes something you can pick up.

Why It Is Orange

Fresh peridotite is dark green. Break a chunk open and you will often see it inside.

The orange-brown surface is rust. Peridotite is rich in iron, and after thousands of years of exposure to air and water, the outer layer oxidizes to the bronze colour the Tablelands are known for. The effect changes with the light. Under flat midday cloud the massif can look dull and brown. In late afternoon sun it glows.

Look closely at the rocks along the trail and you will also find serpentinite, a transformed version of peridotite with pale veins running through it in a pattern that looks like snakeskin. That process is still happening inside the Tablelands today, as water works its way into the rock.

Why Nothing Grows

The barrenness is the second thing everyone notices, and it has nothing to do with climate. The same weather supports thick forest a short distance away.

The problem is the soil. When mantle rock breaks down, it produces ground that is high in magnesium and heavy metals like nickel, chromium, and cobalt, and very low in the nutrients most plants need: nitrogen, phosphorus, potassium, and calcium. For most plants, it is simply toxic.

What does grow here is worth looking for precisely because it has solved that problem. Low, tough plants like moss campion and yellow mountain saxifrage cling on in sheltered spots. Carnivorous plants such as butterwort and pitcher plants manage by catching insects to supplement what the soil will not give them. Along the seeps and small streams you will see more life than you would expect. Take the time to look down as well as out.

Walking the Tablelands

The main trail is an easy, roughly four kilometre return walk following Winterhouse Brook into a bowl at the base of the massif. It is mostly flat, suitable for most fitness levels, and takes an hour or two depending on how often you stop. Interpretive signage along the way covers the geology well.

Going higher is a different matter. The plateau above is steep, loose, and unmarked, and snow can linger in the gullies well into June. It is serious terrain and not somewhere to improvise without experience and good conditions.

A few practical points:

Wear real footwear. The rock is abrasive and uneven even on the main trail.

Bring layers. There is no shelter on the massif. Wind and weather arrive quickly and the bare rock offers nothing to hide behind.

Time it for the light. Late afternoon brings out the colour. Midday cloud flattens it.

Stay on the trail near the plants. The vegetation here grows slowly in very hard conditions. A careless boot undoes years.

Why It Is Better With Context

You can walk the Tablelands trail on your own and it will be memorable. But this is a landscape where knowing what you are looking at changes the experience entirely. The difference between a rusty hillside and a piece of ancient ocean floor that has travelled up from beneath the crust is almost entirely interpretation.

That is also true of Gros Morne as a whole. The Tablelands sit within a park that holds fjords, highland plateau, coastal communities, and some of the most varied geology in North America, all within a short drive of each other. Seeing it well takes time and someone who knows how the pieces connect.

See Gros Morne With Us

Rob and Pam personally guide our [Gros Morne & Western Newfoundland Signature Journey], seven days built around the park’s geology, landscapes, and communities, with the Tablelands timed for the best light and conditions on the day. [Get in touch] and we will talk through what a week in Western Newfoundland looks like.