Final answer:
In a narrow V-shaped valley, most erosion is directed downwards as the river cuts deeply into the valley floor due to the steep gradients.
Step-by-step explanation:
In a narrow V-shaped valley, most erosion is directed downwards. This directional erosion is due to the force of the water as it flows down the steep gradients of the valley sides, cutting deeper into the valley floor and forming a narrow, V-shaped cross-section.
As the river carries sediment and erodes its channel, the action is primarily vertical rather than lateral, distinguishing it from wider valleys where erosion can be more evenly distributed along banks and across floodplains.
Over time, the process of erosion can lead to the formation of gullies and other erosional features, contributing to the landscape's continual change.