Is a chunk of central Ottawa an island?

Beth McLarty Halfkenny sits on the shore of the Rideau River outside of Carleton University's campus. The water rushes by as she looks on toward the point where the river and the Rideau Canal converge.

It might not be the first thing you think of, but it's the various local waterways that make a central part of Ottawa — in some people's minds — a sneaky island.

This Is Ottawa listener Matt Bell wrote in to ask host Robyn Bresnahan whether that's in fact the case.

Bordered by the Rideau River to the south and east, the Rideau Canal to the west, and the Ottawa River to the north, the stretch of land from Lowertown down to Carleton University could technically be considered one.

That's according to McLarty Halfkenny, a geologist at Carleton University's earth sciences department.

In fact, McLarty Halfkenny told This Is Ottawa that — for similar reasons — Hull's old town in Gatineau, Que., could also be deemed an island.

"We always think of islands as being in the middle of the Pacific Ocean or something," McLarty Halfkenny said. "I like the question, because it made me think more deeply about this space that we live in."

Impact on biodiversity likely minimal

While the canal has created a sort of artificial island, McLarty Halfkenny said it likely hasn't had an impact on the plants and animals we see on land.

However, it has attracted more underwater life by creating a new habitat.

"When you open up the canal, you create a new waterway. So new vegetation is going to grow around that new waterway. And then that brings more different animals," she said. "It certainly will bring plants and animals that weren't normally there to a new area when you create more waterways."

While human changes to Ottawa's geography might not have a significant impact on how other lifeforms experience our city, several natural geologic features do.

Ottawa is situated on fault traces, where rocks have displaced each other over time. They're responsible for the dips and falls in Ottawa's waterways at Hog's Back Falls and the Hartwells Locks.

Geological structures like the Ottawa-Bonnechere Graben are responsible for creating the Ottawa Valley, which can even have an impact on the weather patterns we experience. The valley holds pollen which contributes to severe allergy seasons and a microclimate that contributed to wildfire smoke hanging in the air in the summer of 2023.

"Lots of the features that are part of everyday life in Ottawa are created by the geology," McLarty Halfkenny said. "So that's pretty awesome."