The 120 metre wall was either a fish-trap or a dyke for protection against rising sea-levels, archeologists believe.

This paper argues that the Pleistocene record of humans in Australia is much more puzzling than the literature acknowledges. We begin with population estimates, and the claim that pre-LGM populations were small (under 200,000, perhaps even under 100,000); a claim based on the number and character of sites. We argue (i) the inference from archaeological traces of low population numbers is risky because the proxies are demonstrably unreliable; (ii) if pre-LGM numbers were indeed under 200,000, that requires special explanation, and no obvious one is available; (iii) the Pleistocene record suggests that those foragers used their lands in ways not well represented ethnographically, and in ways not currently well understood; (iv) the LGM record itself is mysterious. Previous readings of paleo-environmental data predict an intense crisis in forager lives, but there is little signal of such a crisis.