Pooh, Percy and Berty came across a V-shaped valley in the upper course part of the river, near the source.
The infant river is small and runs fasts cutting into the landscape and deepening the valley sides. The river at this stage has very little energy to erode sideways, however it does erode downwards.
'Fingers' (ridges) of land stick out into the valley making the river flow around them. These 'fingers' are called spurs.
The source is behind Pooh
Any material that falls from the valleys sides usually rolls into the river below and when the velocity of the river is fast enough the material is transported away.
A valley is a long trough in the landscape that has been eroded by a river or a combination of river and glacier action.
A valley which resembles a 'v' in cross section. These valleys have steep sloping sides and narrow bottoms.
Spurs are the 'fingers' (ridges) of more resistant rock around which a river is forced to wind as it passes downstream in the upper course. Interlocking spurs form where the river is forced to swing from side to side around these more resistant ridges.
is the wearing away of the bottom and sides of the rivers by the force of the water, and material carried by the water.