Hiking the Tablelands of Gros Morne National Park is a truly unique experience. These rocks are hard to find on the Earth’s surface, so if you’re visiting Newfoundland this is a stop not to be missed!
Back to Basics
What exactly makes the geology of this area so special? To answer that question, we’ll first need to take a trip back to elementary school geography class and recall the internal structure of the Earth. The Earth is composed of several layers. The crust, the outermost layer, is where we are. This is the ground we walk on, the rocks we mine, the mountains we climb, and the very bottom of our oceans. This crust ranges in thickness from 5-10 km under the oceans, to up to 70 km thick on the continents. At the very center of the Earth is the molten, iron-rich core. And in between the crust and the core is the mantle.
Mantle Facts
- Mostly solid
- Silicate-rich, with minerals like olivine, garnet and pyroxene
- About 2900 km thick
- 84% of the Earth’s volume
- Between 1000 and 3700 degrees Celsius
- Moving constantly via convection currents
These facts are from National Geographic. Check it out for more information on the different layers of the Earth.
Geology of the Tablelands
Ophiolite Complex
As these are from the mantle, you can bet that these rocks are full of silica-rich minerals. The Tablelands are an ophiolite complex. These complexes occur when an oceanic tectonic plate collides with a continental plate. Since continental plates are much thicker, the oceanic plate is crumpled and pushed up on top of the continental plate. This movement can actually pull some of the Earth’s mantle with it, creating an ophiolite like we see at the Tablelands.
To see the detailed geology of ophiolites, and an in-depth explanation of their creation, visit OSU’s Volcano World page.
Peridotite
When looking at the Tablelands, the most distinctive rock type is peridotite. These are the mantle rocks themselves. Peridotite is primarily composed of olivine, which is a green mineral. The insides of these rocks are therefore a dark green color, while the outsides are red from iron staining. But don’t test this yourself when at Gros Morne National Park! This is against park rules. If you want to see the green olivine on the inside of the Tablelands rock, just ask a member of the park staff. There may even be some samples to investigate at the Discovery Center!
Peridotite is not a nutrient-rich rock, so there is very little greenery growing in the Tablelands. This lack of life, and the distinct red coloring of the rocks, creates a landscape that looks out of this world. The sharp contrast between the Tablelands and the surrounding area is striking, and lends added visual intrigue. Definitely bring your camera, to capture this beautiful area!
Hiking the Tablelands
Other ophiolites have been found throughout the world in Cypress, Oman, and California, but the Tablelands are among the easiest to get to and interact with. Gros Morne National Park offers guided hikes, but you can also hike and explore the Tablelands on your own. Follow the stream running along the valley to enjoy some small waterfalls as you hike, or just have fun and explore as Katie did in her Hike This article. Don’t forget to bring a Newfoundland hiking guide along to find other amazing hikes in the area.
When you find yourself hiking the Tablelands, be sure to take a moment to appreciate the awesomeness of our Earth, and imagine the extreme forces that created those mantle rocks you’re standing on.