Integrated geomorphological–geophysical characterization of periglacial processes and frozen ground distribution in the easternmost edge of the Darwin range, Tierra del Fuego (54° S)

The southernmost Andes of the Tierra del Fuego archipelago (54° S) contain extensive periglacial landscapes below 1,000 m a.s.l., yet ground‐ice distribution in this region remains only partially documented. Existing probabilistic models suggest that sporadic permafrost may occur above 700–800 m a.s.l.; however, field‐based validation remains limited, leaving uncertainties regarding the geomorphic reorganization of mountain frozen grounds upon ice retreat. We present an integrated geomorphological and geophysical investigation of a glacial cirque in the Pirámide Hills (Yendegaia National Park) aimed at identifying frozen ground organization and post‐glacial processes. Detailed geomorphological mapping, combined with Electrical Resistivity Tomography (ERT), reveals widespread periglacial forms, including patterned ground, frost polygons, solifluction lobes and debris‐mantled slopes indicative of active cryogenic dynamics. High‐resistivity zones (>10 3 –10 6 Ω·m) occurring above ~750 m a.s.l. indicate the presence of frozen ground within rock glaciers and coarse moraine deposits, whereas lower slopes display only shallow and discontinuous frost signatures during Austral summer. These findings highlight the dynamic reorganization of recently deglacierized areas, where remnant frozen cores and fragmented ice lenses exert potential structural control on sediment routing, and may influence hydrological connectivity, as well as slope stability. By integrating surface and subsurface evidence, this study refines the southernmost permafrost edge in the Americas, showing how frozen grounds are strongly compartmentalized by geomorphic setting and debris inheritance. The findings provide a reference for evaluating frozen ground transition in postglacial environments and aid the cryosphere inventories for new cryoforms with potential for geotourism development in protected areas.