The river erodes vertically, This happens because of hydraulic action, this is where the water gets in the cracks of the rocks. Another reason this happens is because of Abrasion, and this is where the rocks scrape along the bed of the river
The rock on either side is exposed to weathering. Wind and rain batter the rock and cracks it
Rock becomes very weak so it gets transported down into the river
A V-shape valley is formed.
Interlocking spurs are like fingers of land that jut out into the river
Interlocking spurs are formed because the river does not have enough energy to cut through the land