This Thornton Peak Landslide followed heavy, unseasonal rainfall after a tumultuous 137-mm fell in a relatively short period overnight, precipitating the slumping of a significant portion of the oldest rainforest in the world. After a dry June, an exceptional downpour of 137-mm on the first night of July initiated a landslide from the top of Thornton Peak (Wundungu.) A large swathe, estimated, to be about 10 hectares in area was totally denuded from the peak to the lowland rainforest. It was on the eastern face of the mountain, acknowledged as the centre of significance in a rainforest that has endured for 180-million years.
Thornton Peak (Wundungu) attracts by far the highest rainfall in Australia. In the coastal lowlands of the Cooper Valley, we average 5.5-metres/year and merely doubling this average, which is a very conservative allowance, puts the Peak’s average at 11-metres/year. This average annual rainfall is more than 2.5-metres higher than that of Queensland’s highest mountain, Mt. Bartle-Frere. Thornton Peak has provided refuge to the last fragment of the oldest-surviving rainforest in the world and the values that specialise in the higher altitudes are so restricted in their distributions that is is hard to reckon how catastrophic the landslide was.