Complete the crossword using the clues given

123456789
Across
  1. 3. High land with steep sides.
  2. 5. An area with little or no rainfall.
  3. 7. A low land between two hills or mountains
  4. 9. A very big sea.
Down
  1. 1. Flows from the mountains, through the plains
  2. 2. A flat land at the top of a hill
  3. 4. A large body of salty water.
  4. 6. A flat land on which cities are developed.
  5. 8. Their tops are covered with snow sometimes