ABSTRACT: There has been a longstanding hypothesis that the Jacobsville Sandstone (in the Upper Peninsula and Ontario) is equivalent to the Bayfield Group (in Wisconsin and Minnesota). We set out to test this hypothesis based on the collection of over 70 samples and several drill cores studied of the Jacobsville Sandstone, and the Bayfield and the Oronto groups. The samples were plotted on a QFL diagram. What we found was that the Jacobsville Sandstone exhibits the same pattern of immature-mature-immature lithology as the Bayfield Group in Wisconsin. We propose herein that the Jacobsville Sandstone be elevated in rank to the Jacobsville Group. We also herein extend the Orienta, Devils Island, and Chequamegon sandstones into Michigan and Ontario. We also propose the Jacobsville Group be extended into Wisconsin and replace the Bayfield Group. There are two additional Jacobsville lithostratigraphic units named herein. One is the Lâ€™Anse Formation at the base of the Jacobsville Group which is likely valley fill deposits. The second is a unit that likely represents a fault proximal facies named herein as the Jackson Creek Formation, which interfingers with all of the other formations of the Jacobsville, except for the basal Lâ€™Anse Formation.