What if you could drain all of Earths oceans? What would it look like? You might be really surprised. You see that the surface has two main features. It has continents and ocean basins. Continents are large land areas. These are the areas that are mostly above sea level. Ocean basins extend from the edges of continents. They include the ocean floor and Earths deep ocean trenches. You will also notice the ocean floor is not flat. It too has many Continents are much older than ocean basins. Some rocks on the continents are billions of years old. Ocean basins may only be millions of years old. Because the continents are so old, a lot has happened to them! As we view the land around us, we see landforms. Landforms are physical features on Earths surface. These features change over time, but how? There are actually two types of forces at work. 
What is a landform?
A feature on the bottom of the sea