Flint Island Coal Mine?!

Someone once proposed establishing a coal mine on tiny Flint Island, offshore from Donkin, Cape Breton!

Richard Brown, manager of the General Mining Association (GMA), wrote a book in 1871 called the Coalfields and Coal Trade of the Island of Cape Breton. In it, he explains how the GMA’s three-decade monopoly on Nova Scotia’s minerals came to an end in 1857-58, partly due to resentment that the monopoly prevented others from pursuing mining opportunities.

In the four or five years after the monopoly ended, “more than forty licenses for exploration were issued for tracts in the Sydney coal-field alone,” as well as exploration licenses for coal in several other parts of Cape Breton.

“One enthusiastic adventurer even took out a license for a submarine area, accessible only by sinking a shaft upon the little rock called Flint Island, more than a mile from the mainland,” wrote Brown. The Gardiner coal seam outcrops (it is visible at surface) on Flint Island, which is presumably why the island was seen as having mining potential.

Many of the exploration licenses came to nothing because they were taken out by people who did not have the funding (and expertise, perhaps) to develop a mine. Some people got lucky and were able to sell their licenses to bigger companies. Others simply gave them up.

A coal mine on Flint Island was an improbable but nonetheless intriguing suggestion in that era.

The Old Victoria Mine in Victoria Mines was likely the first mine in North America planned to be completely under the sea floor. It opened in 1865, around the same time as the idea for mining under Flint Island. However, it was obviously much simpler to establish a submarine mine – or any mine, for that matter - on the mainland instead of an island less than two hectares in area.

What kind of dock facilities would have been built on Flint Island? Could coal have been loaded directly onto ocean-going ships or would it have been hauled to Donkin in small boats/barges, which would have significantly increased the cost of the coal? How would equipment and supplies have been landed on the island? (Again, shuttling materials and equipment from onshore would have added to cost and made the island’s coal less competitive in the market.) Would miners have had to commute by boat each day or would housing have been built on the island?

While the island would have been a little bigger in the 1860s – a century and a half of erosion and rising sea levels have shrunk it a bit – it would have been only modestly larger. Was there even room to build the mining facilities? Or to dig a decline tunnel that would have allowed for enough rock cover between the subsea tunnels and the ocean floor above to prevent serious leaks of sea water into the mine? (This was a major problem at the Old Victoria Mine because its slopes were built too close to the shore. The lack of rock cover allowed sea water to enter the mine through faults or other structural features of the geology.)

One thing the proponent did have right is that there was coal under the ocean in that area. The Sydney Coalfield extends from Cape Morien to Cape Dauphin and 300 kilometres offshore. 98% of the coalfield is underwater – it extends almost to the south coast of Newfoundland.

However, without diamond exploration drilling – which was invented in the early 1860s in Geneva but not available in Nova Scotia at that time – finding the coal seams might have been a matter of guesswork and luck. They could have tried to calculate their locations based on what was known of them from onshore mining, i.e. where they were at the shore and what the angle of their dips were. But it would have been a risky proposition. The geological map below that shows the coal seams under water is based on geological knowledge developed many years later.

The book’s author, Richard Brown - not to be confused with his son, Richard Henry Brown, who succeeded his father as the GMA’s manager in Cape Breton in 1864 - was the first to see the potential in mining coal under Cape Breton’s sea floor. He built the Princess Colliery in Sydney Mines with its main shaft near the shore and the workings entirely under the ocean. The shaft was started in 1868 but due to water leaks, the seam was not reached until 1876. The shaft had to be lined with metal through 300 feet of water-bearing rock to ensure safety. It was a significant engineering achievement and it paved the way for most Cape Breton coal to be mined under the ocean.

Despite his vision and daring, even Brown described the person who came up with the Flint Island idea as an “enthusiastic adventurer” – which was likely an understatement. Many mines built in more favourable circumstances in that era failed for a variety of operational and economic reasons. The additional challenges of mining under the ocean from Flint Island ensured the idea was not seriously pursued.

Flint Island has had a lighthouse on it since 1856. The first lightkeeper had to catch rainwater in casks because he found it impossible to dig a well on the island – perhaps foreshadowing the challenges of establishing a mine there.

Despite its name, Flint Island is made of sandstone, not flint rock. The name is the translation of what the French called the island: “Ile a pierre à fusil.”