(1) A river's action when an avulsion takes place. (2) The region of land circumscribed by the old and new channels which are the result of an avulsion. One should consult the laws of the particular state in the matter of the effect on the titles and boundaries, including the interpretations through the leading judicial opinions. It appears in all cases that (a) the title to the land within the region cut off and the rules applicable to the old bank-line boundary remain what they were before the avulsive cutoff took place; (b) boundaries described as the center of the main channel and those as along the medial line between the former banks remain as situated immediately prior to the avulsion; and (c) the rules of navigability and new-bank-line riparian right apply to the new channel the same as to the old channel.