These two round tanks, called Horton Spheres, sit atop a hill above the decommissioned Turner Valley Gas Plant in Southern Alberta. They were originally used to contain iso-butane and n-butane. The iso-butane was shipped to the Imperial Refinery in Calgary where it was used in the manufacture of high octane gasoline components for the production of aviation fuel. During and just prior to World War II, much of this fuel was used by the British Commonwealth Air Training Plan. For more information on the BCATP and to see some pictures of what remains today, check out my photos of the WWII Air Training Base near Vulcan, Alberta in Gallery 5. Although still in good condition and quite serviceable, the spheres presently sit unused, serving only as a reminder of the dark and silent gas plant further down in the valley.