Avulsion Definition:

Osborn's Law Dictionary defines avulsion as:

"The cutting off of land from the property to which it belongs, as may happen if a river changes course. The ownership of the land remains the same."

In Mozley and Whiteley's Law Dictionary (1962):

"Avulsion: the sudden removal of soil from the land of one man, and its deposit upon the land of another, by the action of water. The soil in such case belongs to the owner from whose land it is removed."

Volcanic activity is another way avulsion can increase territory.

In a 1971 decision of the Supreme Court of Arizona (State v Bonelli Cattle), Justice Struckmeyer wrote:

"It is common knowledge that rivers move sometimes so slowly as to be imperceptible during the lifetime of any single individual, and sometimes so rapidly by floods that the river's banks visibly disintegrate. Where the change is sudden and rapid, the change is said to be by avulsion. Erosion, on the other hand, is the eating away of the soil by the river's current, and is a gradual, imperceptible process. Where the river moves by erosion, the boundary moves with the stream, but where the river moves by avulsion, the boundary remains in the center of the old channel."

"[A]vulsive changes are generally events so momentous that evidence is available to establish them.... The rule of law is that in the absence of clear evidence to the contrary, the movement of the river will be presumed to be by erosion."

REFERENCE:

• Duhaime, Lloyd, Legal Definition of Accretion
• Duhaime, Lloyd, Legal Definition of Alluvion
• Duhaime, Lloyd, Legal Definition of Dereliction
• State v. Bonelli Cattle Company, 489 P. 2d 699