corrasive

What Powell calls the "recession of cliffs" comes into play. The erosive and corrasive power of water being the chief land sculptors, it is evident that there will be a continual wearing down of the faces of the bounding cliffs. The softer beds will be cut away faster than the harder, and where these underlie the harder the latter will be undermined and fall.

Frederick Samuel Dellenbaugh - The Romance of the Colorado River : The Story of its Discovery in 1840, with an Account of the Later Explorations, and with Special Reference to the Voyages of Powell through the Line of the Great Canyons

A suspicion arises, on contemplating some of these apparent discrepancies, that the prevailing conditions of corrasion are not what they were at some earlier period, when they were such that it was rendered more rapid and violent; that there was perhaps an epoch when these deep-cut tributary canyons carried perennial streams, and when the volume of the Colorado itself was many times greater, possessing a multiplied corrasive power, while the adjacent areas were about as arid as now.

Frederick Samuel Dellenbaugh - The Romance of the Colorado River : The Story of its Discovery in 1840, with an Account of the Later Explorations, and with Special Reference to the Voyages of Powell through the Line of the Great Canyons

In summer, then, the amount of water seeking outlet by these drainage channels to the sea was enormously multiplied, and the corrasive power was correspondingly augmented. When the ice caps finally began to permanently diminish, the summer floods were doubtless terrific.

Frederick Samuel Dellenbaugh - The Romance of the Colorado River : The Story of its Discovery in 1840, with an Account of the Later Explorations, and with Special Reference to the Voyages of Powell through the Line of the Great Canyons