Red brick or not, 'city building' is something Kirkor certainly knows nothing about. If it weren't for their cut-rate fees and borderline-abusive employee treatment, they'd be out of business tomorrow.
I knew there'd be a day where my first year physical geography course would come in handy!
It's not iron per se, but clay that has experienced oxidization (iron oxide) as a result of chemical weathering. It seems to be fairly common on the west side of Mississauga, from the 403 up to Meadowvale.