“Time is a sort of river of passing events, and strong is its current; no sooner is a thing brought to sight than it is swept by and another takes its place, and this too will be swept away.” – Marcus Aurelius It is both the opposed transience and the solidifying nature of geological processes which frame the archaeological and architectural narrative of this delicate project. This ancient landscape constantly shifts, as one remnant appears alongside the disappearance of another. Extending 140m horizontally into the base of the two-billion-year-old Kuruman Hills, Wonderwerk Cave is a cross section through time. The cavern was formed by a subterranean river when this region of the Northern Cape was submerged beneath the sea and within its depths, water-carved clefts, hand-painted surfaces and encased fragments bear silent testimony to the rich stratifications of multiple pasts. Within a modern stratum, offered here as an intentionally momentary presence, emerges a contemporary steel and timber walkway – inserted for the purpose of safe passage – without endangering the site. While programmatically simple, the brief required a response in which a clear understanding of the spatial ramifications for intervening in such a valuable and sensitive site were inherent; through material, scale and tectonics. Under the protection of the South African Heritage Resources Agency (SAHRA), the Wonderwerk Cave National Heritage Site is managed by the McGregor Museum in Kimberley, 150km to the south. An active (and increasingly-more significant) archaeological laboratory, the site attracts researchers from around the world – and recent findings suggest the oldest record of controlled (human) fire, dated around 1 million years ago. The translation of detailed surface mappings into suggestive spatial design investigations established a set of tight tectonic ‘rules’ in which the client, archaeologist, architect and builder were heavily invested. Through this collaborative trust, the end result is a structure that introduces a new (slightly surprising) spatial quality to the cave, in which artifact, laboratory and museum folds into one sinuous narrative. Flanked by archaeological excavations, the walkway unfolds as a prefabricated kit of parts, assembled in-situ. With no ground anchors, the structure relies on self-weight for stability and interconnectedness for strength. It can be entirely dismantled into components small enough to carry; and it can be removed to leave no trace. The impermanence of the structure is deliberate; an suggests another transient layer within this place where the architecture of the earth itself is in a constant state of flux. In some instances, it could be argued that archaeology and architecture pursue opposing agendas. But here, in the path of an ancient dialogue between water and rock, humankind and earth, we discovered that our interests are perhaps not all that dissimilar in the quest to make sense of ourselves in this ancient landscape we call home. Africa.