What is an example of 'avulsion'?

Avulsion refers to the sudden and rapid removal of land, typically due to a natural event such as flooding, earthquakes, or landslides. This phenomenon can dramatically alter land boundaries in an instant. In contrast to gradual processes, which might take years or even decades to change the landscape, avulsion occurs suddenly and typically leaves the remaining land pieces dramatically altered or reduced in size.

The other choices describe different processes that do not fit the definition of avulsion. For example, persistent flooding that gradually changes a landscape represents a gradual process known as erosion, which is the opposite of avulsion, as it occurs over time rather than in a sudden event. Similarly, the slow build-up of land over decades describes sediment deposition, another slow process, while the act of selling a portion of land involves a legal transaction and is unrelated to the physical changes in land caused by natural forces.