He examined beds high on the hill which had been taken as seashells showing that St. Helena had risen from the ocean in recent times, but Darwin identified them as extinct species of land-shells.
El a analizat albiile de scoici de pe dealuri, care demonstrau că Sf. Elena se înălțase din ocean relativ recent, dar Darwin le-a identificat ca specii dispărute de scoici de uscat.