What is the feature called at the base of a waterfall formed by erosion?

The feature at the base of a waterfall formed by erosion is known as a plunge pool. This is an area that has been worn away by the force of the falling water, creating a deep basin. As water cascades over the edge of a waterfall, it creates turbulence, which increases the erosive power of the water, often leading to the development of this pool. The plunge pool is significant not only for its geological formation but also for its role in the ongoing process of erosion, whereby the falling water gradually erodes the rock beneath it, causing the waterfall to retreat over time.

In contrast, the terms "water pool," "fall basin," and "waterhole" do not accurately describe the specific geological feature created by the erosive forces at the base of a waterfall. Each of these terms may refer to bodies of water, generally without the specific context of erosion and waterfalls that defines a plunge pool.