The surface of the Earth is made up of many different landforms. The shape of a land area is also known as topography. The topography of a land area can be flat, sloping, hilly or mountainous. Elevation, elevation, and relief determine the topography of an area. Elevation is the height above sea level. Relief is the difference in elevation between the highest and lowest parts of an area. A landform is a topographic feature formed by the process that shapes the Earth's surface. All landforms have an elevation and relief. A landform region is a large area of ​​land with similar topography. There are 5 different types of landform regions in the United States; coastal plains, inland plains or lowlands, mountains, plateaus or highlands, and plains or mountains. The 3 main types of relief are plains, mountains and plateaus. A terrain composed of flat or slightly rolling terrain with low relief is called a plain. A coastal plain is a plain located along a coastline and having both low altitude and low relief. A plain far from the coast is called an interior plain. An interior plain had low relief, but elevation can vary. A landform with a high altitude and high relief is called a mountain. Mountains are usually part of a mountain range or group of mountains closely related in shape, age, and structure. Mountain ranges constitute mountain systems and mountain systems constitute a mountain belt. A plateau is a relief with a high altitude and a more or less flat surface. Scientists divide the Earth into four spheres: the lithosphere, hydrosphere, atmosphere and biosphere. The lithosphere is the solid, rocky outer layer of the Earth. It contains continents and smaller land masses like islands. The atmosphere is the outermost sphere and...... middle of paper ...... often develops meanders, or a loop-like bend in the course of a river, where it flows at through easily eroded rocks or sediments. Sometimes the meandering rivers form a feature called Oxbow Lake, a meander that has been cut off from the river. The deposits create landforms such as alluvial fans and deltas. An alluvial fan is a large, sloping deposit of sediment formed where a stream leaves a mountain range. Sediments deposited where a river flows into an ocean or lake form a landform called a delta. Groundwater is the term geologists use for underground water. A deposit that hangs like an icicle from the roof of a cave is called a stalactite. Slow drops form a cone-shaped stalagmite from the ice floor. Karst topography is a type of landscape in rainy regions where there is limestone near the surface, characterized by caverns, sinkholes and valleys..