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Cape Breton Highlands National Park of Canada

Geology

A view of the plateau through a naturally carved sea arch at Trout Brook, since collapsed.
The dominant feature of northern Cape Breton is the plateau. Here it is seen through a naturally carved sea arch at Trout Brook, which was there for much of the 20th century but has since collapsed.
© Cape Breton Highlands National Park

The dominant feature of northern Cape Breton is the Cape Breton Plateau, averaging 350 metres at its edges but rising to more than 500 metres at its centre! The Cape Breton Plateau is part of the worn down Appalachian mountain chain which stretches from Georgia to Newfoundland. Extending over 70% of the park, the plateau appears flat-topped but actually consists of broad, gently rolling hills, deeply cut by steep-walled river canyons and broad valleys.

On the west coast the plateau meets the Gulf of St. Lawrence in steep cliffs. On the east, the highlands border the Atlantic Ocean in a more gently sloping coastal plain with low headlands and a few long sandy beaches.

A view of the coastline on the west of the park; steep cliffs plunge down to meet the ocean.
On the west coast the plateau forms an awe-inspiring coastline where it meets the Gulf of St. Lawrence.
© Cape Breton Highlands National Park / E. Rooney

A billion years of change: the formation of Cape Breton Island - Cape Breton Island is made up of three main groups of rocks: the Bras d'Or terrane, the Avalon terrane and the Blair River inlier. Some of the oldest rocks in the Maritime Provinces are found on Cape Breton Island, in the Blair River inlier.

The formation of the Cape Breton Plateau - The plateau as we see it today is the product of millions of years of geological change, including mountain building, erosion, and glaciation.

Faults and canyons in Cape Breton Highlands National Park - Faults, glaciers and rivers have all worked the landscape over millions of years to produce spectacular river canyons.