The purpose of this study is to describe and correlate rocks of Mississippian age within the state of Nebraska. Shales, generally classified as Chattanooga and commonly referred to as Devonian or Mississippian in the northern Mid-Continent, have been included in this study, although these shales are more generally believed to be Devonian and not Mississippian by most stratigraphers and paleontologists at the present time. Since rocks of Mississippian age are present only in the subsurface of Nebraska, the basic information for this report is derived from the microscopic study of cuttings and cores from test wells drilled within the state