Canso Causeway

The Canso Causeway was built with 10 million tons of quarried rock - but not without incident!

On November 29, 1954, Norweigan freighter SS Lionne ran into the Canso Causeway. Because the Causeway was not yet open, it was not on British Admiralty navigation charts. The Lionne's crew didn’t know we were in the process of connecting Cape Breton to mainland Nova Scotia and crashed into the unfinished causeway. (Fortunately, the SS Lionne survived the crash.)

It took 10 million tons of stone to build the Causeway because it is 24 metres wide at the top, 192 metres wide at bottom, and 65 metres deep in some spots. Some called it the eighth wonder of the world when it opened.

The quarry that provided the stone is immediately next to the Causeway on Cape Porcupine. It was started in 1952 for the Causeway project. It was thought there might not be enough rock to build the Causeway but the quarry completed the job and is still operational today. It went dormant after the Causeway was built but became active again in the late 1970s and has been run by several companies since.

Today, the quarry continues to be a major employer in the area. Stone is quarried on the mountain, dropped over the side and loaded onto ships for transport to places like the eastern seaboard of the United States. For example, its rock was used as fill in Orlando, which is quite swampy. Disney World and some of Orlando’s key infrastructure was built on stone from the quarry.

The Strait of Canso used to freeze every winter but the causeway created a world class, ice-free, deep-water harbour.

There was a time when people did not need the Causeway to cross the Strait of Canso. You could have walked from Cape Breton to mainland Nova Scotia 13,000 years ago, during the last ice age, because sea levels were about 70 metres lower than today. (Sea levels are lower during ice ages because so much water is frozen in glaciers, and sea levels rise as glaciers melt.) Cape Breton became an island about 8000-9000 years ago as sea levels rose.

The Strait of Canso was just a stream valley a half million years ago. It is believed to have been deepened by glaciers several times during glacial advances since then, most recently 21,000 years ago, giving us the deep body of water we know today.

Gold was reportedly found at Cape Porcupine but no actual mining for it took place there. Gold has been found in many places in Nova Scotia that might surprise you, even if the amount found was too small to mine. Learn more at