A more thorough explanation:

Alluvion

Alluvion is when soil, sand, and other parts of land slowly build up or erode away over time due to the movement of water, usually near rivers or oceans. If land erodes, the owner of the property loses the right to any removed part of the property. This is different from avulsion, which is when large sections of land are rapidly disconnected from the property due to extreme weather and flooding. In avulsion, the original owner can keep the dislodged portion of the land. Disputes can arise over whether an event is alluvion or avulsion, as this determines who owns the affected property.

One example of alluvion is when a river slowly changes its course over time, causing the shoreline to move and the land to build up or erode away. Another example is when waves from the ocean gradually wear away at a beach, causing it to become narrower over time.

An example of avulsion is when a sudden flood causes a large section of land to break away from a property and move elsewhere. In this case, the original owner can keep the dislodged portion of the land.

These examples illustrate how alluvion and avulsion can cause changes to property ownership based on the speed and cause of the land movement.