Shell mound formation in coastal northern Australia

Abstract

Shell mounds are late Holocene deposits typically dominated by a single shell species. In northern Australia these mounds are associated with prograding coastal plains. The largest and most numerous are at Weipa on Cape York Peninsula. Archaeologists claim that these mounds were formed by generations of shellfishing Aborigines. This hypothesis is false because most of the shells from the type-site are of a similar radiocarbon age. Mapping and augering of two contrasting shell mound environments along the Mission River at Weipa demonstrates that mound formation is a natural consequence of local chenier plain development. This is supported by shell ages from across the Weipa landscape. The shell mounds at Prumanung originated as a coarse shell berm. The large mounds on the Uningan plain originated as small shell cheniers. The only reasonable explanation for the transformation of these natural shell deposits into tall, steep-sided mounds is the mound-building behaviour of the Orange-footed Scrubfowl Megapodius reinwardt. Similar mounds composed predominantly of sand and gravel are also present at these localities. The strong likelihood that the shell mounds are natural shell deposits raises serious questions about basic principles of shell midden archaeology. New methods for distinguishing between cultural and natural shell deposits are needed.