Polybius: decipherer of Hannibal’s alpine route and ancient stratigrapher

Abstract

After interviewing surviving soldiers of Hannibal’s alpine invasion of Italia and sketching out the Punic Army route, Polybius, a Greek general serving as advisor to Scipio Aemilianus, retraced the Hannibalic invasion of 218 BC, in or about 150 BC. Polybius later recounted Hannibal’s route from Cartagena through the Pyrénées and Gaul (France) to the Rhône River, crossing near Arles, north to Orange, Drôme River to the Durance, diversion to the Guil River, and on to the Col de la Traversette. At ~ 3000 m asl, the Traversette provides a vantage point overlooking the Po River and the vaunted, much discussed rockfall, a ~ 250 m wide rubble mass that blocked passage of Hannibal’s elephants and horses. Soldiers could pass, but clearing a path for animals took three days to allow the army to recover in the wide valley plain below, prior to exfil onto the lower Po River plains. Polybius probably spent scant time at the rockfall but noted it was a two-stage event, older rock largely eroded, partly superposed by younger rock. This brilliant observation and assessment qualify Polybius as probably the first stratigrapher in history. His separation of rockfall lobes on lichen cover and weathering/tonal contrasts, marked a seminal event in earth science history.