1. scrubber - a device used in coal-burning power plants that allows the gases in the smoke to dissolve in water until the pH of the smoke increases to a safe level.
2. plucking - process that adds boulders, gravel, and sand to glacier's bottom and sides as water freezes and thaws and breaks off pieces of surrounding rocks.
3. Periosteum - tough, tight-fitting membrane that covers the surface of bones.
4. leaching - removal of minerals that have been dissolved in water.
5. creep - mass movement that occurs when sediments slowly inch their way down a hill. It is common in areas of freezing and thawing.
