Interlocking spurs are a follow on form the v-shaped valleys. This means interlocking spurs are normally formed after a v-shaped valley, further downstream. An interlocking spur is made up of protrusions of more resistant rock. The river will have to wind around them. It could also be formed by the river starting to meander and as it starts to do so it will vertically erode the path it travels along. Weathering will break apart the sides making it into a v-shape, and in essence interlocking spurs are just winding v-shaped valleys.

Interlocking spurs also lead into meanders further down stream. Compared to meanders, interlocking spurs migrate down stream much slower.

Hopefully now you have leart something.