I made a big post but it didn't go through for some reason...
To answer questions, it is a mafic sill, part of the Nor'Wester Mountains or Nor'Wester Escarpment. There is a road up the back to a lookout located half way up, and trails to the summit.
Tower Mountain, southwest of Thunder Bay, is the second highest point in Ontario but like Ishpatina Ridge (the highest), it is not a mountain. The Sleeping Giant has a prominence of 380 meters and is the highest mountain in Ontario by that measure.
Mount McKay is about the same height, width and depth as downtown Toronto.
Northeast of Thunder Bay, there are canyons. Here is the most famous one: