Mountains are land masses that project well above their surroundings. They are higher and steeper than hills and end in a peak. Mountains are defined based on volume, elevation, relief, spacing, steepness and continuity. Mountains are often defined by their highest point reaching at least 1000 feet above the base.
Hills are mounds or raised areas of land. Hills are generally not as tall or steep as mountains. Hills are often defined as by their highest point reaching between 501 and 999 feet above the base, with anything higher constituting a mountain. Other words used to describe hills are knowe, knoll and hillock. Hills that are created artificially are known as mounds.
Plains are a type of flat land that only experience slight changes in their elevation. Another type of flat land is the plateau, but plateaus are higher than surrounding land areas. Plains feature relatively high reliefs with flats. Types of plains include steppes and prairies. Plains occur both as plateaus and lowlands.
Glaciers are masses of ice that move slowly over land. Glaciers make up the largest fresh water reservoir on the planet, and cover large areas in the polar regions and mountain ranges on every continent. There are several types of glaciers, including tidewater glaciers, alpine glaciers and ice sheets. Glaciers are formed when snow and ice are accumulated, compacted and compressed into ice crystals which grow over a period of hundreds of years.
Different bodies of water exist in topographical maps, including rivers, ponds, lakes and oceans. Oceans make up two-thirds of the earth's surface, and are comprised of salt water. Lakes and ponds are bodies of fresh water, and lakes are larger than ponds. Rivers are flowing bodies of water that flow into larger bodies of water such as seas and oceans.
