rivers- upper course landforms

what are v shaped valleys and interlocking spurs?

• v-shaped valleys: valleys with steep and high sides. their cross profile resembles a ‘v’

• interlocking spurs: ridges of overlapping higher ground with a river winding through them

how are v shaped valleys formed?

1. in upper course, rivers try to reach base level- this results in vertical erosion. the material carried by the river help erode the channel downwards, resulting in a deep notch in the landscape

2. the sides of the notch are left exposed and are attacked by weathering. this weakens the sides and the ground breaks up into loose pieces

3. the weakened ground is forced to move bc gravity or rain- topple into the river.

4. this results in a valley with steep sides. this process occurs throughout the upper course.

what is a waterfall?

• waterfall: where water falls down a vertical drop in a channel, usually from a considerable height

explain the formation of a waterfall

1. a small sudden drop forms along a river when a band of soft rock follows a band of harder rock (erodes quicker bc. less resistant)

2. erosion causes harder rock to be undercut. hydraulic action and abrasion cause a plunge pool to be formed

3. this process continues until there’s an overhang of hard rock.

4. the plunge pool is deepened and extends backwards as the power of the falling water hits the rock, forcing it to crack, as well as throwing rocks against it (hydraulic action + abrasion)

5. the overhang eventually collapses, which now means the river falls at a position further upstream

6. this process continues, eventually forming a gorge (narrow, vertical sided valley)