[A Formerly Proud Canadian]

From what I understand of the 'oil sands'/'tar sands' mining process, the 'oil sands' run almost like 'seams' in the ground, as coal would. There is little, if any, that does not have 'overburden' atop the seam, so there is little chance of the ground catching fire. If something like that happened, I imagine it might be akin to an underground 'peat bog' fire, burning and smouldering for years unless it was dug up and extimguished.

Here is a diagram from the Imperial Oil (69.6% owned by ExxonMobil) website, detailing the process used at the 'Kearl' site:
Note the shovel digging the oil sand located under the overburden. The 'overburden' is removed and the 'oil sands' are mined and processed.

Historically, the Natives in the area, would use oil sands on the surface or seeping out of the banks of the Athabaska River, to waterproof their canoes. The 'easy stuff' is all gone.

[stayathomemom]

I am wondering what the nature of the soil will be after an event like this? Sand + heat = glass, right?

[zeestephen]

Thanks for the very informative reply.

I hadn't realized that the most valuable “sand” was still well below the surface.

Years ago, I recall reading a science article that explained that almost all the petroleum in the world is slowly but steadily working its way up to the Earth's surface, where it then evaporates or is consumed by microorganisms.

The “tar pits” in Los Angeles, as I recall, were the final step before the petroleum was broken down and recycled into the atmosphere, oceans, and surrounding land.