Authors: Willmott, W.F., Beaman, R.J.
Publication: B.G. Lottemoser, P.W. Whitehead, P.N. Nelson and R.J. Beaman (Editors), Rocks, Landscapes and Resources of the Wet Tropics. Geological Society of Australia (Queensland Division), Brisbane, Australia, pp. 21-24.
All mountains and hills are gradually worn down by the agents of erosion. Erosion starts with the gradual softening and decomposition of the rocks (weathering) near the surface by penetrating water, air, roots and biological activity. As the rocks are gradually exhumed, they also crack from the release of pressure from the removal of the material above. Water becomes channelled along these fractures, and removes the softened rock on the sides of the joints, grain by grain, over millions of years. Such erosion can allow flowing water to cut deeply into the rocks, producing long narrow gorges such as those we see today in the Wet Tropics (for example, those of the Barron, Mossman, Tully and Herbert Rivers).