Item WE039002: Water can gradually wear away the solid rock of river valleys as much as thousands of feet over millions of years.

Which of the following statements describes how water can change river valleys?

  1. Water can gradually wear away the solid rock of river valleys as much as thousands of feet over millions of years.
  2. Water can wear away the solid rock of river valleys no more than several feet over many millions of years.
  3. Water can wear away the solid rock of river valleys no more than several inches over many millions of years.
  4. Water cannot wear away the solid rock of river valleys, even over many millions of years.