Farther down stream the canyon starts to widen by other means.

5 types can be seen in just this one shot.

• mass wasting
• potholes
• attrition
• atmospheric weathering
• peeling (exfoliation)

Mass Wasting

When the sides of the canyon get too steep and the rock can no longer support its own weight, it collapses into a pile of rubble.

Potholes

These still continue to bore into large obstacles on the bottom of the channel.

Attrition

Large boulders are rolled along the floor of the canyon and break off pieces of rock on the bottom and sides.

This deepens and widens the channel and also encourages mass wasting of the sides.

This mass wasting produces more boulders to be forced through the channel by flood waters.

Atmospheric weathering

Exposure of fresh rock to the elements results in chemical changes (mainly oxidation) and crumbling of the outer surface of the rocks.

This is evident from the darker discoloration of the rocks higher up and exposed the longest to the elements.

Peeling (exfoliation)

The high temperatures in the baking sun by day and cold desert nights cause high rates of expansion and contraction. This causes the outer layers of solid rock to peel off and fall into the canyon, giving certain slopes a rounded appearance.

Other posts in this series

Augrabies - The hidden river
Augrabies - The Falls and Floods
Augrabies: a "heart of stone" for valentines day.
Augrabies: Reading the geological history written on the walls
Augrabies: Lizards everywhere