Abstract

Simple inspection of the orientation and pattern of a drainage net provides direct information concerning regional slope and degree of structural control in the net as well as, indirectly, hydrologic and climatic information. All of these factors are of interest in interpreting environments of deposition of ancient sedimentary sequences. Inspection of integrated paleodrainage nets can thus provide significant paleogeographic insight. Although rarely exposed at the surface, paleodrainage nets are common in the subsurface and are frequently delineated on maps of mature coal mines.

As an example, two Mid-Carboniferous drainage nets from West Virginia are described and analyzed. Net geometries show a transport direction from southeast to northwest and a slope of about six feet per mile. The orientation of the nets and the trellis arrangement of the channel lengths indicate structural control by the same tectonic framework that uplifted and deformed the resultant strata (Alleghenian deformation). This observation is substantiated by cross sections and isopachous maps for the strata. Discharge, drainage density, drainage area and other hydrologic parameters are calculated from the nets.