Is the TTC taking a proactive approach to Toronto’s geological history?

As the TTC prepares to embark upon its plans to tunnel below the city late next year, building badly-needed new subway lines as part of the Toronto-York Spadina Subway Extension, has sufficient thought been given to the geological heritage that may lie beneath?

This is a development I’ll be continuing to monitor for Spacing magazine; the winter issue will be out in the coming weeks.


Photo by Liam Lahey

Andrew Stewart, archeologist, Strata Consulting, works in the field of cultural heritage. He’s currently directing excavations at Fort York for the proposed visitors centre. It was Stewart that wondered what the TTC’s plan is with respect to burrowing beneath the city and if any thought had been given to geology.

“Geological heritage has been on my mind the last few years. If you look at the Don Valley Brickworks . . . it was a huge excavation into the ground that became famous world over,” he said. “In the early 20th Century, it was an important place that exposed 150,000 years of geological history; very well-preserved history. Toronto gained a reputation more than 100 years ago for its preservation of layers of Ice Age history that other places didn’t have.”

Carolyn Embury, spokesperson for the TTC’s TYSSE Project, said if cultural heritage resources are discovered during any excavation, the TTC will suspend work and an assessment will be completed by the Ontario Ministry of Culture.

The TTC has completed a great deal of upfront work in regard to archaeological assessments for the upcoming dig, she added; as it turns out, they did find something worthy of further investigation at an undisclosed location.

“Considering our up front investigations, we don’t anticipate finding anything but in any event, we are prepared,” she said. “We’ve taken a proactive approach . . . we’ve done testing and all the assessments that tell us when we have to proceed (with further testing). We have one assessment that is ongoing that suggests we need to dig further to find out what’s there.”

Prof. Paul Karrow is a Pleistocene geologist at the University of Waterloo. He formerly worked for the Ontario Dept. of Mines (later the Ontario Geological Survey) from 1957 to 1963, conducting geological mapping. He said Toronto is world famous for its exceptional geology.

“One must depend on chance exposures in excavations to see what is below. When I worked at ODM I also was in touch with Metro Works and Roads to log some of their many borehole cores, as well as the Dept. of Highways’,” he recalled. “I visited various excavations on the weekends recording the available exposures, but what I could see was a drop in the bucket compared to the large amount of such places to see.”

When the TTC was digging the Yonge and Bloor Streets subway lines in the 1950s and 1960s respectively, the transit company invited geologists to survey the lines as they were being excavated. Many discoveries were made, including a new species of Ice Aged deer that was found at Yonge and Queen that had been preserved in the shallow water deposits of Lake Iroquois; the precursor of Lake Ontario.

If Toronto had a geological survey office, it’d go a long way to studying and preserving that which is found underground.

“There has long been frustration on the part of geologists that there is no requirement for the filing of borehole records for all construction work (in Toronto). There is no organization responsible for recording what is found, other than by chance,” Karrow said. “The attitude here is exploitive; ‘the land is here for the taking’. I would like to see more respect for the landscape as nature made it and more care taken to preserve it and minimize disturbance.”

The City of Toronto does have an archeological management plan it’s been working on since 2003. The plan would identify areas of “archeological potential that would be subject to an archeological assessment prior to development.”


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