Image Credit: SUBMITTED/David Gregory
June 18, 2023 - 7:00 AM
It’s not as easy to find volcanic cannonball rocks around Summerland as it used to be.
Some have been claimed by collectors, like former Summerland mayor David Gregory, while others were sold as novelties at local fruit stands in the 1940s and 1950s.
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The spherical lava rocks range in size from a ping pong ball to ones that are two metres in diameter. That two-metre sphere – the largest one Gregory ever saw – was unearthed when Highway 97 was getting widened in 2007. Many others became visible during the same project.
When Gregory was mayor he contacted B.C.’s Ministry of Transportation and his local MLA to suggest preserving the rocky spheres that became exposed along the highway. He said there was an interest in doing so but they were deemed to be a safety issue and had to be removed.
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Gregory wants to see them preserved said they’re believed to have formed after getting ejected as lava from a volcano 55 million to 60 million years ago.
“North of Summerland, the viscosity of lava was just right to create the spherical cannonballs,” he said
Nearby volcanos are known to have been active at that time, which would have ejected “lava bombs,” Gregory said.
And although many of the lava bombs formed symmetrically, those ones are mostly found at sea level – which would have been a few metres higher than where it is today. The lava that landed in the water is believed to have cooled down quickly and retained its shape, and most of crystals hardened on the outside layer of the cannonball.
At higher elevations, the lava rocks take on more of a tear drop shape with a small tail. The small deformities probably happened because they stayed hot longer compared to the spheres that hit the water. And crystals can be found more evenly throughout the tear-shaped balls.
Gregory estimates that about 80% of them are tear-shaped.
Both cannonballs have been split in half. On the left is a spherical ball that would have cooled off much more quickly compared to the tear-shaped ball on the right.
Image Credit: SUBMITTED/David Gregory
But whichever shape they take on, it’s easy to tell them apart from regular rocks because they’re much more dense and heavy, and they have a crusty texture.
They can be found throughout town, but are most common north of Summerland, Gregory said. He’s heard reports of the same spherical rocks getting found as far away as Naramata or West Kelowna, but he has doubts as to whether they could have travelled those distances without human intervention.
For anyone who’s interested in seeing some of the the rock balls up close, Gregory donated his old collection to Fitzpatrick Family Vineyards in Peachland, where they are now on display.
Some people are still finding them in nature, like Bad Company lead singer Paul Rodgers who now calls the Okanagan home. He posted a photo of himself with his find to Twitter.
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