Viking Altar Rock
The boulder was found in 1943 and is roughly 8.2 m (27 ft) long by 5.2 m (17 ft) wide. It has four roughly triangular holes about 1 meter above the base. The rock is promoted as an attraction as part of a "Trail of the Vikings" featuring supposed evidence of Viking exploration of Minnesota. This is however conjecture.
- Skystone, a Western Washington erratic with pits drilled in its upper surface
- Michlovic, Michael B. "Folk Archaeology in Anthropological Perspective" Current Anthropology, Vol. 31, No. 1 (Feb., 1990), pp. 103-107
- Patricia Monaghan, "A Viking Visitation?" in Wineries of Wisconsin and Minnesota (Minnesota Historical Society, 2008), p. 82 online.
- Hughey, Michael W.; Michael G. Michlovic. ""Making" history: The Vikings in the American Heartland". International Journal of Politics, Culture, and Society. 2 (3). doi:10.1007/BF01384829.