I am standing on a dune looking out to sea. It’s 2024, but I’m thinking about a very different time. Hundreds of thousands of years ago this 350km stretch of southern African coast looked very different. It was home to giant zebra, bird species that are now extinct, giant tortoises and crocodiles. Our hominin ancestors roamed the area.
We know some of these facts because of body fossils. But South Africa’s Cape south coast is also home to another rich source of information, which our research team from the African Centre for Coastal Palaeoscience at Nelson Mandela University has documented over the past 15 years: fossilised tracksites. These trace fossils date to the Pleistocene epoch, with ages ranging from 400,000 years to 35,000 years. Most of them are preserved in a rock type known as aeolianite (cemented dune surfaces).
The tracksites are an example of what’s known as geoheritage, which the Geological Society of South Africa calls a “descriptive term applied to sites (geosites) or areas of geologic features with significant scientific, educational, cultural, or aesthetic value”. The importance of geoheritage is becoming increasingly recognised at a global level; for example, it is relevant to the United Nations’ 2030 Agenda Sustainable Development goals, and Unesco’s Global Geoparks “celebrate the links between geological heritage and all other types of heritage”.
Given our discoveries on the Cape south coast, as well as what other researchers have found in the West Coast National Park, about 120km outside Cape Town, it’s clear that South Africa is home to some remarkable geoheritage.
Read more:
Gigantic wolverines, otters the size of wolves: fossils offer fresh insights into the past
In a recently published scientific paper we outlined this geoheritage, examined the threats it faces from both nature and human interference, and suggested how it could be preserved.
These sites have almost certainly come and gone over previous centuries and millennia without our knowledge. However, now that we know about them and can appreciate them, scientists and heritage authorities have an obligation to celebrate, protect and preserve them as vitally important geoheritage items, and to raise awareness about this precious, newly discovered resource.
Threats
Raphael Rivest/Shutterstock
The Cape coastal sites are threatened on many fronts. Cliff collapse events expose new sites, while known sites slump into the sea or are eroded rapidly by wind, high tides and storm surges. In addition, humans find these surfaces attractive and engrave graffiti into them, potentially damaging the precious fossil tracksites.
Read more:
Graffiti threatens precious evidence of ancient life on South Africa’s coast
Many of the sites are of hominin origin. Some are ancestral human trackways; others preserve patterns made by our ancestors on dune surfaces that may be some of the oldest examples of art. These patterns, which we’ve dubbed ammoglyphs, have been reported only on the Cape coast and nowhere else in the world. They are therefore of global heritage value. One site even contains the oldest known fossil footprint attributed to our own species.
Read more:
World’s oldest _Homo sapiens_ footprint identified on South Africa’s Cape south coast
I regard each of these sites as a miracle of preservation, of something that we are now able to recognise and interpret, against all the odds. We know what to look for and we know these surfaces have the capacity to record this priceless heritage. We just need to be vigilant and keep visiting this coastline, especially after storm surges or cliff-collapse events.
Managing the sites
Mixed with this good fortune, however, come problems, questions, and management challenges.
Charles Helm, Author provided (no reuse)
Which sites require active management, and how should they be ranked in importance? What is the scientific and heritage value of the sites? Is physical recovery possible by helicopter or four-wheel drive, or is replication through digital technology the most appropriate route to follow? And if physical recovery is possible, are there suitable repositories for specimens? What if nothing is done – how significant are the threats to a site’s integrity, and how accessible or remote is it?
In addressing these challenges, we came up with a ranking checklist. At a global level, such checklists are surprisingly rare; we are aware of only two examples.
We used these as a basis for our checklist, modifying their criteria to be applicable to the Cape coast. Criterion categories included a site’s uniqueness and scientific value, threats in the current location, accessibility and feasibility of recovery, research and education value, and the potential for post-removal care.
The resulting checklist forms the basis for constructive collaboration with management authorities like national parks, provincial nature reserves, municipalities or private landowners, as well as national and provincial heritage authorities. Good working relationships between these roleplayers and scientific researchers are key if geoheritage sites are to properly handled and preserved. The published article and the ranking checklist are not an end in themselves. We hope they will provide a starting point for meaningful collaboration and discussion.