A recently proposed and fundamentally different Cenozoic geology and glacial history paradigm (new paradigm) is used to explain previously reported and other anomalous Monongahela River drainage basin drainage system evidence (observable on detailed topographic maps in the form of barbed tributaries, asymmetric tributary drainage basins, large abandoned meander cutoffs, and poorly explained transverse drainages and abandoned transverse drainages). The north-oriented Monongahela River drainage system according to the accepted Cenozoic geology and glacial history paradigm (accepted paradigm) originated during preglacial times and was blocked by continental icesheets to form today’s Ohio River. Based on Missouri River drainage basin topographic map evidence the new paradigm predicts the Monongahela River drainage system developed during immense and prolonged south- and southwest-oriented continental icesheet melt water floods. The new paradigm also predicts icesheet caused regional uplift created a deep “hole” in which a thick icesheet was located and which forced south-oriented melt water floods to flow in southwest directions along the deep “hole’s” southeast rim (now the Ohio River-Atlantic Ocean drainage divide) until continued deep “hole” rim uplift and the deep valley headward erosion from space being opened up by icesheet melting reversed the flow direction to create the north-oriented Monongahela River drainage system. This new paradigm interpretation explains previously reported and other anomalous Monongahela River drainage system topographic map evidence and suggests the Monongahela River drainage system developed while a continental icesheet melted and not during preglacial time as has been commonly reported.