What does vertical erosion primarily create?

Vertical erosion primarily creates a V-shaped valley due to the process by which a river cuts downwards into the bedrock. This action is prevalent in the upper course of a river where the gradient is steep, allowing the river to gain energy and erode the landscape vertically. As the river continues to erode downwards, the sides of the valley are eroded less violently, leading to the characteristic steep sides and narrow base that resemble the letter "V."

In contrast, the other features mentioned, such as a wide valley, floodplain, and oxbow lake, are typically associated with different types of erosion and sediment deposition processes that occur later in the river's journey, especially in its middle and lower courses. Thus, the recognition of V-shaped valleys as a product of vertical erosion is fundamental to understanding how rivers shape the landscape over time.