The sand percent contours were produced by the Louisiana Geological Survey and were digitized from Chapter 11, Cenozoic, in The Gulf of Mexico Basin, Volume J, The Geology of North America (1991). The data are provided in three shapefiles--one for each stage (Lower, Middle and Upper) of the Miocene series. These datasets contain basic data and interpretations developed and compiled by the U.S. Geological Survey's Framework Studies and Assessment of the Gulf Coast Project. Other major sources of data include publicly available information from state agencies as well as publications of the U.S. Geological Survey and other scientific organizations. In cases where company proprietary data were used to produce various derivatives such as contour surfaces, the source is cited but the data are not displayed.