Two major forces that shape the surface of the Earth are the atmosphere and the ocean. These two things wear down mountains, turning them into sediments. These forces help form the landscapes of the Earth.
There are both internal forces and external forces that shape the surface of the Earth. Erosion, in the form of wind, water and ice, is an external force. It is a natural process, though it is increased due to humans' land use. Volcanoes are an example of internal forces at work shaping the Earth. Magma is forced to the Earth's surface, becoming hot lava and creating changes in the surface of the Earth.