Radiocarbon age for estuarine shells from Lakelands, Lake Ellesmere (Te Waihora), New Zealand : short communication

Shells of the estuarine species Mactra ovata from Lakelands, Lake Ellesmere, New Zealand give a 14C radiocarbon age of 670 plus or minus 67 BP. Their occurrence presents a problem as currently Lake Ellesmere is a brackish lake, separated from the Pacific Ocean by Kaitorete Barrier, a mixed sand and gravel barrier. According to previous research this barrier has enclosed a water body behind it in the position of Lake Ellesmere for up to 8000 years. Since the mid Holocene, at least three fluctuations between lacustrine and estuarine conditions are thought to have occurred. These fluctuations are believed to be associated with the avulsion of the Waimakariri River, to and from Lake Ellesmere. This study adds to the previous research by providing a timeframe within which one of these estuarine events occurred. (author)