Extent of available data.
This data layer indicates the extents of underground mined areas in the Cuyuna Range. It was developed by the Natural Resources Research Institute. The areal extents of underground mine workings have been digitized from found and geo-rectified surface and level maps of the Cuyuna Range underground natural iron ore mines (not all levels of the Armour No. 1, Armour No. 2, and Croft mines were digitized). This information can be used for mapping, documentation, potential energy storage exploration (pumped hydro, compressed air), monitoring, analysis, and land use planning purposes. It generates a surface reflection of the extent of underground workings, and hence, areas of potential subsidence and/or underground void space. Note that due to incomplete/non-existent/unfound maps, the mined extents may exceed what is shown.