Quirks & Quarks

Why are the Tablelands of Gros Morne National Park barren?

The rocks at the site are rich in toxic metals that plants can't tolerate

The rocks at the site are rich in toxic metals that plants can't tolerate

The Tablelands of Gros Morne National Park in western Newfoundland provides a rare glimpse of the Earth's mantle. (CANADIAN PRESS/Colin Perkel)

This week's question comes to us from Rochelle Collins in Kamloops, BC: 

The Tablelands of Gros Morne National Park in Newfoundland are one of the few places in the world where you can walk on the Earth's upper mantle. But I've been confused as to why over the last millions of years they've been exposed, there's no dirt deposited on them for vegetation to grow. Can you offer an explanation?

Dr. Penny Morrill, a professor in the Department of Earth Sciences at Memorial University, says the unique composition of the mantle rocks at the site is behind the phenomenon.

Mantle rocks are poor in nutrients that plants need to grow, and rich in toxic metals such as magnesium and iron that plants can't tolerate. Some dirt does accumulate as rocks erode on the Tablelands from weathering and erosion, but without vegetation, it's easily blown away since there are few plants to hold it in place. 

However, if you look closely, a meagre amount of soil does exist at the site. It's nestled in between rocks, and you can spot many small and dwarf plants living among the rocks. One of them is known as the serpentine sandwort, which is only found growing in soils containing serpentine minerals


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