rift n.

"split, cloven, burst asunder," c. 1300, past-participle adjective from rive "to tear, rend."

"tear in pieces, strike asunder," c. 1200, from a Scandinavian or North Sea Germanic source akin to Old Norse rifa "to tear apart," from Proto-Germanic *rifanan "to tear, scratch" (compare Swedish rifva, Danish rive "scratch, tear"), from PIE root *rei- "to scratch, tear, cut" (see riparian).

"of or pertaining to river banks, situated on or near a river bank," 1849, with -an + Latin riparius "of a river bank," from riparia "shore," later used in reference to the stream flowing between the banks, from ripa "(steep) bank of a river, shore."

This is probably etymologically "break" (and indicating the drop off from ground level to the stream bed), or else "that which is cut out by the river," from PIE root *rei- "to scratch, tear, cut" (source also of Greek ereipia "ruins," eripne "slope, precipice;" Old Norse rifa "break, to tear apart;" Danish rift "breach," Middle High German rif "riverbank, seashore;" English riven, rift).

Riparious, of animals, "living on or in river banks," is from 1650s.