The present disclosure relates to a visual interface for identifying layers within a subterranean formation. One example method includes identifying one or more sets of data associated with a subterranean formation; computing, by operation of one or more processors, a working line based on the one or more sets of data, the working line representing a numerical average of the one or more sets of data; presenting the working line and the one or more sets of data in a common plot in a visual interface; identifying one or more layer boundaries for one or more of the layers of the subterranean formation; and generating layer data based on the one or more identified layer boundaries and the working line.