Earth’s Diverse Landscapes: Mountains, Rivers, Wetlands, and Oceans
Earth’s Diverse Landscapes
Mountains
Mountains form when the Earth’s plates collide, causing the land to fold upwards. This process, which takes millions of years, creates mountain ranges. Notable examples include the Andes in South America, the Rockies in North America, the Alps in Europe, and the Himalayas in Asia. The peaks of some mountains are perpetually covered in snow and ice due to their high altitude, resulting in less oxygen. Even on lower slopes where snow melts in summer, only the hardiest plants and animals can survive.
Rivers
Rivers are natural channels of water flowing downhill, playing a crucial role in the water cycle. They originate from springs, glacial meltwater, or rainwater accumulating on saturated ground. Near its source, a small river, often called a stream or brook, flows rapidly. Streams merge to form larger, slower rivers that eventually flow into a lake or the sea. The force of the water and the stones it carries erodes the underlying rock. Over millions of years, a river can carve out a wide valley.
Wetlands
Wetlands are found on the edges of lakes, near the seashore, or in areas flooded by rainwater or rivers. Many plants and animals thrive in these waterlogged conditions. However, some species are threatened as wetlands are often converted into farmland or building sites. The Everglades in Florida, USA, is a slow-flowing wetland, a haven for wading birds, alligators, and other animals. Water levels fluctuate seasonally.
Seashore
The seashore is the zone where land meets the sea, encompassing rocky cliffs, sandy or pebble beaches, and marshy wetlands. At high tide, much of the low-lying seashore is submerged. The sea deposits sand, pebbles, and other materials on the shore, along with tiny food particles for the creatures living in the sand or on the rocks. These creatures serve as prey for crabs, starfish, and seabirds. Seashore plants anchor themselves to rocks rather than putting down roots in the ground. Many remain moist even after the tide recedes, providing shelter for small animals.
Oceans
Oceans, vast expanses of saltwater, cover more than two-thirds of the Earth’s surface. The ocean floor, thousands of meters underwater, consists of plains, trenches, ridges, and volcanoes. Some volcanoes rise above the water, forming islands. Ocean water plays a significant role in weather patterns. Ocean currents, both warm and cold, influence the climates of nearby lands. Oceans are also home to a wide variety of life, from microscopic plants to giant whales.
Coral Reefs
Coral reefs are found in tropical, shallow waters around volcanic islands or near rocky mainland coastlines. They are built from layers of skeletons of tiny animals called polyps. Over many years, colonies of polyps can build up great banks of coral, known as reefs. There are many different kinds of corals, and their bright colors make a coral reef look like an undersea garden. Only the living surface of a coral is colored; the layers of skeletons underneath are white. The living layer of tiny polyps feeds on zooplankton that drift by in the current.