* Mountains: Formed by tectonic plate collisions, volcanic activity, and erosion. Some famous examples include Mount Everest, the Himalayas, and the Rocky Mountains.

* Valleys: Formed by rivers, glaciers, and erosion. They can be wide and flat or narrow and steep. Examples include the Grand Canyon, the Death Valley, and the Nile River Valley.

Earth's surface is incredibly diverse, with mountains, valleys, plains, deserts, oceans, and more!