21. The falls formed when water erosion by streams created gorges through layers of basalt and resistant trachyte. 22. It can be used on any waterway or water containment where there is potential for water erosion . 23. Water erosion of the softer sandstone left behind the columnar structure of harder rock that exists today.24. All areas of the Ancestral Puebloan homeland suffered from periods of drought, and wind and water erosion . 25. The incident was believed to have been caused by water erosion of the limestone beneath Ryan's grave. 26. Schoch states that wind erosion forms distinctive horizontal bands, whereas the water erosion features are clearly vertical. 27. Ploughing leaves very little crop residue on the surface, which otherwise could reduce both wind and water erosion . 28. Rye is very effective in preventing wind and water erosion and it is commonly grown for this function. 29. The cave, which was created by natural water erosion , was fortified with a wall, barred gateway and arrowslits. 30. Differential water erosion , sometimes as part of a freeze-thaw cycle, opens the cracks wider and wider over time.
