World map

Author: Zhou Min, Editor-in-Chief
Publisher:
Publish Date: 2002-08-01
Features: Most of the Earth's surface is covered by oceans, with land occupying only a small portion. The total surface area of the Earth is approximately 51 million square kilometers, of which the area of the oceans is about 36 million square kilometers, accounting for 70.8% of the total surface area. The area of the land is about 14.9 million square kilometers, accounting for 29.2% of the total surface area. In other words, seven-tenths of the Earth's surface is ocean, and three-tenths is land. The land on the Earth's surface is divided into many landmasses of varying sizes by the oceans. Typically, large landmasses surrounded by oceans are called continents, while smaller landmasses are called islands. Continents and their nearby islands together are called continents. This way, the land on the Earth's surface is divided into six continents: the Eurasian continent, the African continent, the North American continent, the South American continent, the Antarctic continent, and the Australian continent. The oceans on the Earth's surface are interconnected, forming a unified world ocean. According to the distribution of land and sea, the world's oceans can be divided into four parts: the Pacific Ocean, the Atlantic Ocean, the Indian Ocean, and the Arctic Ocean. There are no natural boundaries between them, and they are usually divided by underwater ridges or a specific meridian. The elevation of the Earth's surface varies greatly, and its morphology is diverse. Landforms are typically divided into types such as plains, plateaus, basins, mountains, and hills. They are distributed in different scales across the continents, collectively forming a rugged and uneven exterior. The mountains on land have two massive mountain belts: one is the circum-Pacific mountain belt, which extends north-south along both sides of the Pacific Ocean, i.e., the Cordilleran-Andean mountain system that runs through the western part of the North American continent, as well as the mountains along the Pacific coast of Asia and Australia and the islands of East Asia. The other is slightly oriented east-west, stretching across the central and southern part of the Eurasian continent and the northern edge of the African continent. Its western part includes the Alps and the Atlas Mountains, which, after entering Asia, merge with the mountains on both sides of the Turkish Plateau, the Hindukush Mountains, the Karakoram Mountains, and the Himalayan Mountains. They then extend through the western mountains of the Indochina Peninsula and continue to the southern island arc of the Sunda Islands, connecting with the circum-Pacific mountain belt. The two mountain belts are products of the Alpine orogeny, with high and majestic terrain, abundant volcanoes, and frequent earthquakes. The plains on land are generally distributed in the middle of the continents, with high mountains surrounding them on both sides, forming three longitudinal belts of landforms. The North American continent is the most prominent example, and the Australian continent also has a similar topographical structure. However, on the Eurasian continent, plains are mainly located north of the east-west mountain belt, such as the Central European Plain, the Eastern European Plain, the West Siberian Plain, and the Turan Plain. On the southern side, plains are mostly formed by river sedimentation and are distributed between plateaus, such as the Mesopotamian Plain, the Indus-Ganges Plain, and the Northeast Plain, North China Plain, and Middle-Lower Yangtze Plain of China. Large plateaus, which are widely distributed on land, are generally centered around Precambrian continental blocks and have relatively stable crusts with gentle terrain. Examples include the plateau of the African continent, the Central Siberian Plateau, the Mongolian Plateau, the Arabian Plateau, and the Deccan Plateau of the South American continent, as well as the northern plateau of the Australian continent. The Antarctic continent is similar to the African continent, being dominated by plateaus but covered with thick ice layers. Additionally, there are plateaus scattered between young mountain ranges on land, with relatively active tectonic activity, high elevations, and significant terrain relief, such as the Tibetan Plateau, the Anatolian Plateau, the Iranian Plateau, and some intermontane plateaus in the Cordilleran-Andean mountain system. Small landmasses scattered in the oceans, rivers, or lakes are called islands. The total area of islands in the world accounts for about 7% of the total land area, and the largest island is Greenland, located in the northeastern part of North America. Many islands that are very close to each other are collectively called island groups, such as the Malay (South Seas) Archipelago and the West Indies. A peninsula is a piece of land that extends into the ocean or a lake, surrounded by water on three sides and connected to the mainland on one side, such as the Arabian Peninsula and the Indochina Peninsula.