Abstract Ancient human footprints have been known from Managua, Nicaragua, since the 1880s. The main footprint site, long preserved in the Acahualinca Tracks Museum (Huellas de Acahualinca), reveals hundreds of human footprints that represent a minimum of 12 clearly defined trackways and a trampled trail or path. Deer, opossum and bird tracks are also present at Acahualinca, and bison and tapir tracks have been documented from the nearby and stratigraphically equivalent El Recreo site. The age of the Acahualinca footprints is controversial, but the best current estimate is about 2–2.2 ka BP. The Acahualinca site is one of the most scientifically important human footprint sites known from the Holocene. It exhibits footprints that are very abundant, well-preserved, accessible for study and part of a large sample that demonstrates variation within a single population. The Acahualinca site has historical, cultural and archaeological importance in preserving at least two intervals of human occupation, that of the footprints and of the ceramics in much younger layers. Its significance to anthropology and palaeontology as a sub-fossil footprint locality is clear and the volcanological history of the area is intimately related to determining the age and the circumstances of footprint registration at Acahualinca. The Acahualinca footprints merit geoheritage status.

Abstract While Olduvai Gorge, Tanzania, is most famous for its impressive and formative record of early human technology, Pleistocene fauna and hominin fossils, its geological record is equally important. At Olduvai, palaeoanthropologically significant sites are often preserved in primary context (not redeposited), and they can be contextualized within the palaeoenvironments in which the hominins lived. This has provided an exceptional opportunity to assess not only hominin evolutionary changes over time, but also to understand their adaptive behaviour including toolmaking, foraging and sociality. Abundant volcanic material from the nearby Ngorongoro Volcanic Highlands, interspersed within and between archaeology-bearing deposits, made Olduvai a target for some of the earliest applications of radiometric dating using the K/Ar system. Ultimately, the 40 Ar/ 39 Ar dating system has produced ages with exceptional precision. Early radiometric dating at Olduvai helped establish the antiquity of the hominin lineage, and early palaeomagnetic studies (and the ‘Olduvai event,’ the longest normal subchron within the reversed Matuyama Chron) were critical in establishing the importance of Olduvai in the field of geochronology. More recently, high-resolution palaeoclimate studies of the palaeolake that once occupied the Olduvai Basin have helped to reconstruct the palaeoenvironments encountered by hominin species. Over a century of geological research has secured Olduvai's status as an important site for geoheritage.