1. Shapefile of the 1968 Ecological Study for the Twin Cities Metropolitan Area (Composite Intrinsic Suitability) Datasets University Of Minnesota Public content 1968. Paul Jacobs, Rebecca Barney, Len Kne, Ya Tao, and Dan Milz. A digitized version of Ian McHarg's original 1968 Ecological Study for the Twin Cities Metropolitan Area: Composite Intrinsic Suitability. These ma... U-Spatial.