Coastal erosion during the 1980s and 1990s exposed a 300-metre-long midden at Watsons Beach, 40 kilometres south of Dunedin. A midden is an ancient rubbish site, where early Māori cast the remains of their food. These archaeologists are excavating sea mammal and moa remains. The site appears to date from the earliest phase of Māori settlement, 600–700 years ago. It is just one of many coastal archaeological sites that are under threat. Some are being damaged by natural processes, as at Watsons Beach, but hundreds are spoilt by vehicles or grazing stock animals.