Which type of erosion makes a river deeper: vertical erosion or horizontal erosion?

Vertical erosion makes a river deeper. This type of erosion occurs when the river cuts down into the bedrock or soil, deepening its channel over time. As the water flows, it wears away the material at the bottom more effectively than at the sides, leading to a deeper riverbed. Horizontal erosion, on the other hand, widens the river but does not significantly increase its depth.