Final answer:
Headward erosion occurs at a stream's origin and extends it farther from the mouth, increasing the distance between the two points and contributing to river channel evolution.
Step-by-step explanation:
During the process of headward erosion, the point of origin of a stream extends farther away from the mouth as the stream cuts back into its source. This erosion typically occurs where water flow is swift, and it can cut into the land with such force that it creates new channels or extends the stream backward towards its source. As a result, the distance from the mouth to the source of the stream increases.
Headward erosion is a natural process contributing to the evolution of river channels and valleys. It can be caused by factors such as heavy rainfall, melting snow, or changes in land use. Abiotic features like the slope's gradient, sediment type, and rock resistance also significantly impact the rate and extent of headward erosion.