Testing models of Falkland Islands Stone Run formation using cosmogenic nuclide exposure dating

Climate reconstructions across Quaternary glacial cycles are limited in the southern mid-latitudes by a scarcity of terrestrial records. The Falkland Islands (~51°S) offer a key location for addressing this gap. Falklands block streams or ‘stone runs’ are among the most striking and enigmatic landforms on Earth but, despite over a century of study, their origin, and the role of Quaternary climate change, remains debated. We present new constraints on stone run formation using transects of cosmogenic Be-10 and Al-26 measurements. Twenty-six dual-isotopic exposure ages reveal altitudinal patterns that test two competing models: (1) formation during warm, tropical Tertiary conditions, with minimal Quaternary modification; or (2) production and transport under intensely cold, periglacial conditions entirely within the Quaternary. Our results also inform lingering questions about glacier extent and associated climate reconstructions. Falklands stone runs are arguably the most extensive and best-developed blockfield landscapes globally, providing an ideal testbed for examining formation. Our findings advance understanding of long-term blockfield evolution in unglaciated terrain, with implications for similar landscapes worldwide.