The explorers believed volcanic activity was causing the hills to burn, but in fact there is another explanation. The underground oil shales in the area are rich in sulfur and brown coal, causing the rock to spontaneously ignite when the hills erode and expose the combustible gases to oxygen.

Over the years, the sulfur dioxide produced from the combustion has changed the acidity of the area to such a degree that it’s now a different ecosystem than the surrounding landscape. And the normally dark mudstone is baked and bleached by the heat, coloring the cliffs with stripes of red and orange.

Thanks to this strange natural phenomenon, it’s likely these Arctic hills were burning with thick plumes of smoke for centuries before the European expeditions. Indeed, local indigenous populations have long come to the area to gather coal. The nearest community (which is over 60 miles away) is called Paulatuk, which means “place of soot” or “place of coal” in the Inuvialuktun language.