Serving Toronto's most liveable community with the Annex Gleaner

CHATTER: Excavators discover giant rock off Bloor Street (August 2019)

September 2nd, 2019 · No Comments

Contractors excavating to create a BIA-sponsored parkette made a surprise discovery. BRIAN BURCHELL/GLEANER NEWS

Residents got a taste of the ice age in the form of a large boulder found at a construction site on Bloor Street at Major. Construction workers excavating the location of a new parkette dug up the boulder at the end of July.

Joe Desloges, an Earth Sciences professor at the University of Toronto, says that the rock most likely came from an iceberg in Lake Iroquois, which had its shore near Casa Loma.

“If you drill down through here, you mostly hit about 70 to 80 feet of glacial lake sand; below that you get the Georgian Bay formation which is the local geology. To find a big piece of this buried on glacial Lake Iroquois sands means that icebergs were floating around and they had pieces of this embedded,” Desloges said.

It weighs close to two tonnes and is estimated to be between 1.2 and 1.5 billion years old.

According to Desloges, the ice started melting between 25 and 15 thousand years ago. During that melt, stones such as the one on Bloor Street were dropped out of the melting ice into local lake sediments.

Rocks like these are actually common, just not in this area.

“You are more likely to find rocks like this when you look at the gullies and the ravines cutting through the Humber and the Don and creeks,” says Desloges.  

The rock will likely find a new home at one of the many planned parkettes along Bloor Street.

The chair of the Bloor/Annex BIA (and publisher of this newspaper) Brian Burchell says he is fascinated by the discovery, and will try to have the rock placed at a new parkette on Howland Avenue alongside a pollinator garden.

When planning the parkettes, the Bloor/Annex BIA had actually planned to include large granite boulders in the form of artistic seating. 

“For the rock to appear during the excavation period, it kind of validates that plan,” says Burchell. “It gives us a link to the past and to incorporate that into our future plans to make a cottage-like environment in our parkettes seems very appropriate.”

—Juan Romero, Gleaner News


Tags: Annex · News