Geology of Gros Morne
Over 450 million years ago, the earth’s crust split beneath the ocean and, as the plates moved closer together, the oceanic crust and mantle layer of the Eurasia/Africa plate was thrust on top of the sedimentary rock of the North American Continental Shelf. By the time the plates had finished their collision course, a huge chunk of the ocean floor and the upper mantle rock, usually buried beneath it, was exposed. When the continents broke apart again, the rift was 500 kilometres further east, leaving this piece of the Eurasian/African Plate stuck to North America, and providing Gros Morne National Park with a unique cross section of the ocean floor.
This area is world-renowned for its complex geology. The Tablelands, a barren reddish brown plateau that towers seven hundred metres above the Atlantic Ocean, stands alone as an alien landscape amongst the lush and hilly forests that encompasses it. Found between the towns of Trout River and Woody Point in south west of Gros Morne National Park, it was here that geologists proved the theory of plate tectonics.
Geologists once believed that the Tablelands were the remnants of molten rock that had oozed up from deep inside the earth. However, at nearby Lobster Cove, a discovery was made by geologist Robert Stevens that proved they were wrong. He found pieces of rock containing chromite that was over four hundred and eighty-five million years old, which was much older than other rocks found in the area. These tiny pieces had eroded from the Tablelands.
Stevens discovery lead to the fact that the Tablelands, are actually the remains of an ancient ocean floor that existed five hundred million years ago. This ocean, called Iapetus, once lay along the eastern coast of North America from Newfoundland to Florida. Tectonic forces pushed remnants of this ocean upwards so that they were preserved within the super continent, Pangea. It is a truly awe-inspiring sight to behold, as you make your way over these huge slabs, which were once part of the ancient Iapetus Ocean floor.
The Tablelands, are predominantly made of ultramafic rock (peridotite), that lacks the usual nutrients required to sustain most plant life, hence the barren landscape. Because of this, there’s virtually no wildlife, which is an odd concept considering the entire park has thousands of moose. The rock is very low in calcium, very high in magnesium, and has toxic amounts of heavy metals. Peridotite is also high in iron, which accounts for its reddish-brown colour. Underneath this weathered zone, the rock is really a dark green colour.