Upper Course

Characteristics:

• Deep narrow valley (V shaped)
• Interlocking spurs
• Fast flowing river (erosion predominant)
• Pot holes in the river bed
• Rapids and Waterfalls

Deep narrow valleys with interlocking spurs

The main process at work is the downward or vertical erosion of the stream bed. This cuts into the landscape deepening the valley sides.

As the water twists around obstacles such as rocks and boulders the erosion forces undercut outward bends and a snaking pattern is produced. From lower down the interlocking of the spurs of land between the bends blocks the view up the valley.

V-shaped valley with interlocking spurs

Potholes:

Potholes are formed by corrasion. Pebbles carried by the river are swirled around on the riverbed. This action erodes the rock on the riverbed forming potholes. Over time, they may widen and join with other potholes to form larger potholes, and the whole riverbed is deepened.

Rapids:

Rapids are stretches of fast-flowing water tumbling over a rocky-shallow riverbed. Different resistance among rocks cause rapids. They are formed when the water goes from one hard rock that resists the water's erosion to a softer rock that is easier eroded.

Waterfalls:

Waterfalls occur when a band of hard rock lies across the river with softer rock downstream which is more rapidly eroded. At first rapids would form but then develop into a waterfall as the softer rock erodes further. Variations may be caused by the rock structure.

(1) Rock layer is horizontal

(2) Rock layer dips upstream

(3) Rock layer is vertical