Phantom Volcano in South Dakota

Photo: NPS

The Ionia Volcano observed by the Lewis and Clark expedition in today’s northeastern Nebraska. But other “volcanoes” were believed to be scattered along the Trail.

William Clark wrote in September 1804: “I walked on Shore with a view to find an old Vulcanio, Said to be in this neighbourhood by Mr. J. McKey of St. Charles. I walked on Shore the whole day without Seeing any appearance of the Villcanoe…”

Yet, according to Gary E. Moulton, editor of “The Definitive Journals of Lewis and Clark,” there is no evidence of volcanoes in the area. It was mostly likely burning deposits of coal or lignite, similar to those at the Ionia Volcano. James Mackay (“McKey,” as spelled by Clark) was the manager of the Missouri Fur Company and he probably never saw these “volcanoes” first hand. He sent John Thomas Evans up the Missouri River; Evans would make it as far as the Mandan villages. He documented his travels and drew a map that was valuable to Lewis and Clark in the first phase of their journey.

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