They are the result of vertical erosion by the river and weathering.
Freezethaw weathering on exposed valley sides leaves bare rock.
Low discharge of the river deposits the bedload.
A spur is a ridge of highland that extends into the V-Shaped valley.
Potholes are the result of vertical erosion anf abrasion in turbulent flow. Potholes are cylindrical depressions.
Abrasion smoothes the sides of the depression and the river floor. They can widen so much they merge together.
Waterfalls are sudden drops in the gradient of the river channel.
Rapids are often located downstream of waterfalls usually a series of steps. Turbulent water forms due to the high energy levels.