| Term | Definition |
| valley | low land between hills or mountains |
| rift | lowland between hills or mountains |
| canyon | deep valley with high steep sides |
| trench | deep valley with high steep sides |
| volcano | an opening in the surface of the earth from which lava flows |
| seamount | an opening in the surface of the earth from which lava flows |
| volcanic island | an opening in the surface of the earth from which lava flows |
| mountain range | land which rises high above the ground |
| mid-ocean ridge | land which rises high above the ground |
| plains | wide, flat areas of land |
| abyssal plain | wide, flat areas of land |