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Accurate chronology of climatic shifts is critical to understand the controls on landscape and species evolution. Unfortunately, direct dating of continental climate change is hindered by the scarcity of dateable terrestrial products evidencing climatic shifts. Here we use ferruginous indurations from the arid landscapes of the Nullarbor Plain in southern Australia to constrain the timing of Plio‐Pleistocene aridification in the continental realm. We present (U‐Th)/He goethite data implying active induration processes between c. 2.7 and 2.4 Ma. Chemical‐mineralogical and petrographic examination suggests that formation of ferruginous indurations was linked with a decline of the groundwater table, driven by the rapid climatic shift from humid late Pliocene to arid early Pleistocene conditions. Combined with local to global climatic proxies, we conclude that ferruginous indurations are promising targets to obtain absolute ages on landscape evolution to refine continental climatic chronology and improve understanding of the environmental drivers of species diversification and extinction. Plain Language Summary: The reconstruction of Earth's climate record is typically founded on the physicochemical properties of marine sediments. Continental sediments that yield time‐constrained climate information are rare, but important to interpret wider Earth system responses and the co‐evolution of regional climate, landscape, and biota. This study presents direct dating of continental climate change on the Nullarbor Plain to constrain its development as an important biogeographic barrier driving species diversification between SW‐ and SE‐Australia. Age dating of iron‐oxide cements constrains the waning availability of mobile water (e.g., groundwater) and the onset of drier conditions related to global Plio‐Pleistocene climate change. These findings demonstrate that iron‐oxides may provide an excellent continental archive to anchor major climate shifts and help understand associated terrestrial ecosystem change. Key Points: (U‐Th)/He data from ferruginous indurations capture the onset of Plio‐Pleistocene aridification in southern AustraliaCorrelation of induration age with other climatic proxies indicates that ferruginous indurations track terrestrial water table evolutionTiming of aridification constrains evolution of important biogeographic barrier [ABSTRACT FROM AUTHOR]