Second.-The above rule shall not be considered applicable to cases in which a river, by a sudden change of its course, may break through and intersect an estate, without any gradual encroachment, or may by the violence of stream separate a considerable piece of land from one estate and join it to another estate, without destroying the identity and preventing the recognition of the land so removed.

In such cases the land, on being clearly recognised, shall remain the property of its original owner.