Plains
An area of land with a relatively small elevation is called a plain.
Plains are the flattest territories on land, generally below 200 meters in elevation. The plains landscape is broad and flat, with very little undulation, and it distinguishes itself from the hills by its smaller undulations, and from the plateaus by its smaller heights.
There are more types of plains, according to their causes can generally be divided into tectonic plains, erosion plains and accumulation plains, but most of the formation is generally the result of the impact of rivers. Accumulation of plains is in the process of crustal downward movement at a smaller rate, the compensatory accumulation of sediments to form the plains. Flood plains, alluvial plains, marine plains belong to the accumulation of plains. For example, the middle and lower reaches of the Yangtze River are alluvial plains. Erosion plains, also known as denudation plains, is in the crust of the long-term stability of the conditions, weathering materials due to gravity, the role of flowing water and the surface gradually be stripped, and finally formed a stony plain. Erosion plains are generally slightly undulating, such as the plains around Xuzhou, Jiangsu Province, China. Tectonic plains are plains formed by the uplift of the earth's crust or the fall of the sea, such as the Russian plains.
The total area of the world's plains accounts for about a quarter of the total land area of the world, the plains are not only vast, but also fertile land, dense water network, well-developed transportation, is the economic and cultural development of earlier and faster. The middle and lower reaches of the Yangtze River in China are known as the "land of fish and rice". In addition, some important mineral resources, such as coal, oil, etc. are also rich in the plains.
■Middle and Lower Yangtze River Plain
The Middle and Lower Yangtze River Plain in China is east of the Three Gorges of the Yangtze River. It is bounded in the north by the Huaiyang Hills and the Huanghuai Plain, and in the south by the Jiangnan Hills and the Zhejiang and Fujian Hills. By the Yangtze River and its tributaries alluvial. The area is about more than 200,000 square kilometers. The terrain is low and flat, mostly about 50 meters above sea level. The middle plains include the Jianghan Plain in Hubei, the Dongting Lake Plain in Hunan (collectively known as the Two Lakes Plain), and the Poyang Lake Plain in Jiangxi; the lower plains include the plains along the Yangtze River and the Chaohu Lake Plain in Anhui (the Central Anhui Plain), as well as the Yangtze River delta between Jiangsu, Zhejiang, and Shanghai. The climate is mostly northern subtropical, with a small part belonging to the northern edge of central subtropical. The average annual temperature of 14 ~ 18 ℃, the coldest month average temperature of 0 ~ 5.5 ℃, the absolute minimum temperature of -10 ~ -20 ℃, the hottest month average temperature of 27 ~ 28 ℃, frost-free period of 210 ~ 270 days. Agriculture is either biannual or ternary, with annual precipitation of 1,000 to 1,400 millimeters, concentrated in the spring and summer seasons. Zonal soil is found only in the low hills and gentle hills, mainly yellow-brown soil or yellow-brown soil. The southern edge is red soil, and most of the plains are rice soil. Agriculture is well-developed, with a high land settlement index (62.1% in Shanghai, 45.6% in Jiangsu), and it is an important production base for grain, cotton and oil. It is an important grain, cotton and oil production base, producing rice, wheat, cotton, rape, mulberry, ramie and jute. The city is crisscrossed with rivers and streams, and the lakes are scattered everywhere, covering an area of 20,000 square kilometers, equivalent to 10% of the plain. On the plain of two lakes, there are more than 1,300 larger lakes, including small lakes, *** counting more than 10,000 lakes, with an area of more than 12,000 square kilometers, accounting for more than 20% of the area of the two lakes plain, which is the place with the most lakes in China. There are big freshwater lakes such as Poyang Lake, Dongting Lake, Taihu Lake, Hongze Lake, Chaohu Lake, etc., which are connected with Yangtze River and have the function of natural reservoirs to regulate the water quantity and cut down the flood peaks, and they produce fish, shrimp, crabs, lotus, lozenges and reeds, and there are also Chinese sturgeon, Chinese crocodile, baiji dolphin and other world's treasures, so the aquatic products account for an important position in China, and it is known as the hometown of fish and rice. It is one of the most economically developed regions, with cities such as Shanghai, Nanjing, Wuhan, Nanchang, Suzhou, Wuxi, Changzhou, Nantong, Wuhu and Changsha. The main industries are iron and steel, machinery, electric power, textile and chemical, etc. It is an important industrial base. The plains are the hub of China's north-south and east-west transportation networks, with well-developed water and land transportation. The Yangtze River runs through the center of the country, becoming an east-west water transportation artery, which, together with its countless tributaries, constitutes a huge network of waterways.
The world's top ten plains?
(1) The Amazonian Plain in South America: 5,600,000 square kilometers
(2) The Plains of Eastern Europe: 4,000,000 square kilometers
(3) The Plains of Western Siberia in Asia: 2,600,000 square kilometers
(4) The Plains of the Plataformas of South America: 1,500,000 square kilometers
(5) The Great Plains of North America: 1,500,000 square kilometers North American Great Plains: 1,500,000 square kilometers
(6) Asian Turan Plain: 1,500,000 square kilometers
(7) Asian Ganges Plain: 450,000 square kilometers
(8) Asian Indus Plain: 300,000 square kilometers
(9) European Central European Plain: 300,000 square kilometers
(10) Asia Songliao Plain: 250,000 square kilometers
2.
Plateau
Plateau (plateau)
Altitude is generally in the more than 1,000 meters above sea level, the area is vast, the terrain is wide, the surrounding to the boundary of the obvious steep slopes, a relatively intact large-scale uplifted area is called the plateau. The main difference between the plateau and the plains is the higher elevation, it is complete with a large area of uplift to distinguish from the mountains.
The plateau refers to the elevation of more than l000 meters above sea level, a large area, the top surface of the less undulating, around the formation of steep slopes of the highlands. Plateau is known as the "stage of the earth", it is in the long-term continuous large-scale crustal uplift movement. It is distinguished from a plain by its greater height, and from a mountain by its greater smoothness and smaller undulations. Some plateaus have a broad, flat surface with little undulation; some plateaus have rolling hills and great changes in terrain. High altitude plateau, low air pressure, low oxygen content, the use of this low-pressure anoxic environment, can improve the human body's physical endurance qualities, so it has become a sports endurance training "treasure".
Additionally, the plateau area receives more solar radiation, long sunshine hours, solar energy resources are very rich. The boiling point of water in the plateau area is lower than 100 ℃, such as cooking with ordinary rice pots, it will be sandwiched. The plateau can be divided into several types according to the shape of the plateau surface: a plateau with a relatively flat top surface, such as China's Inner Mongolia Plateau; a plateau with a large undulation of the ground and a top surface that is still quite wide, such as China's Qinghai-Tibetan Plateau; and a segmented plateau, such as China's Yunnan-Guizhou Plateau, which is y cut by running water, has a large undulation and a top surface that is still relatively wide. The Loess Plateau is one of the four major plateaus in China, and most of the plateau is covered by thick layers of loess. The Loess Plateau of Shaanxi has complete stratigraphic outcrops and diverse landforms, making it the most typical area of loess natural geography in China.
The Tibetan Plateau, at an altitude of 4,000-4,500 meters and covering an area of 2.3 million square kilometers, is the highest plateau in the world.
Pamir Plateau
Mongolian Plateau
Central Siberian Plateau
Antarctic Ice Plateau
Brazilian Plateau Area of 5 million square kilometers
The Deccan Plateau Located in the Indian Peninsula,
Iranian Plateau Located in West Asia
East African Plateau Generally at an altitude of 1000 -1500 meters
South African plateau 1500-2000 meters above sea level
3.
Basin
Basin
People call a basin-shaped terrain that is surrounded by high (mountainous or high plateau) and low (plain or hilly) in the center a basin. The largest basin on earth is in the middle of the East African continent, called the Congo Basin or Zaire Basin, which is about 1/3 the size of Canada. it is an important agricultural area in Africa, and there are rich mineral resources around the basin.
There are two main types of basins. One is the crustal tectonic movement formed by the basin, known as the tectonic basin, such as China's Xinjiang Turpan Basin, Jianghan Plain Basin. The other is formed by glaciers, flowing water, wind and karst erosion of the basin, known as erosion basin, such as China's Yunnan Xishuangbanna Jinghong Basin, mainly by the Lancang River and its tributaries erosion and expansion.
China's major basins
China has five very famous basins, respectively, Sichuan, Tarim, Turpan, Junggar, Qaidam and other basins, the area of more than 100,000 square kilometers. The Tarim Basin, Junggar Basin, Qaidam Basin and Sichuan Basin are also known as the "Four Great Basins of China".
Tarim Basin
The Tarim Basin, located in the south of Xinjiang Province, is the largest basin in China. The name "Tarim Basin" is a Chinese translation of the Uyghur language, meaning a large basin with "horses without reins". The basin extends from the Pamir Plateau in the west to the border of Gansu and Xinjiang in the east, with an east-west length of about 1,600 kilometers and a north-south width of about 600 kilometers, covering an area of more than 530,000 square kilometers, with an average elevation of about 1,000 meters, which accounts for about one-half of the total area of Xinjiang. It is 2.6 times larger than the Sichuan Basin, 1.4 times larger than the Junggar Basin in the northern border, and more than 10 times larger than the Turpan Basin, making it the largest inland basin in China.
The Tarim Basin lies deep in the hinterland of the Eurasian continent, surrounded by high mountains at an altitude of 4,000 to 6,000 meters, far from the sea, the climate is arid and little rain, the temperature difference between day and night and the seasonal changes are very large, is a typical continental desert climate. Cold in winter and hot in summer, the average temperature in January is -10℃, and the average temperature in July is 25℃, and the temperature difference between winter and summer in the same place can be up to 50℃-60℃, and the temperature difference between day and night is 15℃-20℃. Whenever the turn of spring and summer and fall and winter, the morning and evening cold, often have to wear cotton; and at noon the temperature is very high, wearing a single garment is still hot. Therefore, people use the phrase "wearing a fur coat in the morning and a yarn in the afternoon, and eating watermelon with a fireplace in their arms" to describe the characteristics of the climate here. The basin's rainfall in addition to the western part of the relatively more, most areas of the annual rainfall is below 50 millimeters, the eastern part of the only 10 millimeters or so, and in some places even all year round droplets of rain does not fall.
From the edge of the basin to the center, there are Gobi beaches, alluvial fan plains and sand dune areas, and the whole basin has a ring-like structure. The alluvial plains created by rivers flowing down from the surrounding mountains are generally oases. Large oases include Kashgar, Shadong, Hotan, Aksu and Kuqa. Agriculture is well developed in the oasis, with water canals running across the fields and green trees, producing wheat, corn, rice, cotton and melons and fruits. It is an important production area for grain, long-staple cotton and silk in China. In the middle of the basin is China's largest Taklamakan Desert, covering an area of about 334,000 square kilometers, which is also known as the world's great desert. Due to the large area of the desert and extreme water shortage, few people could enter the center of the desert in the old society, so this big desert was named "Taklamakan", which means Uyghur language, for going in and coming out. In the eastern part of the basin, there is the famous wandering lake, Lop Nur. There are also many inland rivers, and the water supply is not by rain, but mainly by melting snow water from the high mountains.
The Tarim Basin is mainly inhabited by Uyghurs. In the old society, due to the inconvenient transportation and many other reasons, this place is in a natural closed state, and few people come. After the liberation, with the progress of society, the development of science, people's interaction with each other accelerated, the number of people who came to increase, especially the people's government has repeatedly sent scientific expedition to this examination of the natural situation and resources, has found that not only the mineral resources here are rich in a variety of non-ferrous metals and petroleum, as well as a large number of salt mines and so on. With the development of China's construction, these valuable resources will be rationally developed and utilized.
Junggar Basin
Junggar Basin is located in the north of the Tianshan Mountains, between the Tianshan Mountains and the Altai Mountains, northwest, northeast and south are surrounded by high mountains, into an unequal triangle, an area of about 380,000 square kilometers, is the second largest basin in China. The terrain of the basin is slightly tilted from east to west, and the elevation of the eastern end can reach up to 1,000 meters, while the lake and marsh depressions in the west have dropped to 200 to 400 meters, and the water surface elevation of Abbey Lake is only 189 meters, which is the lowest part of the basin.
The topographic structure of the Junggar Basin is similar to that of the Tarim Basin, but there are many gaps in the surrounding mountain ranges, so the shape of the basin is not as complete as that of the Tarim. The eastern and western ends of the basin are more developed, and it becomes China's bore road to Central Asia. The elevation of the basin averages about 500 meters above sea level, and the terrain rises towards the east, connecting it with the Inner Mongolia Plateau. The interior of the basin is a complex landscape with grasslands, deserts, salt lakes and marshes. The deserts are limited to the central and eastern parts, east of the Manas River, collectively known as the Gurbantunggut Desert, where the climate is dry and the sand dunes are smaller and lower in height. To the west of the Manas River, there is more precipitation, and most of the area is grassland and marshland. The western part of the basin has mountain ranges up to 2,000 meters high, but there are several gaps where northwesterly winds blow into the basin, resulting in a cold winter climate.
The Junggar Basin is rich in oil, coal and various metal deposits. Karamay in the western part of the basin is one of China's larger oil fields. The northern Altai Mountains region has been famous for its abundance of gold since ancient times. The Junggar Basin has fewer oases, mainly on the northern side of the Tianshan Mountains; the eastern edge of the basin is largely devoid of oases because there are no high mountain ranges to provide water for their development.
Chaidamu Basin
Chaidamu Basin is the deepest basin on the Qinghai-Tibetan Plateau, and it is an unequal triangle. It is located in Qinghai Province between the Arjinshan, Qilian and Kunlun Mountains, 800 kilometers long from east to west and 350 kilometers wide at its widest point from north to south, covering an area of about 220,000 square kilometers, and consisting of a number of small intermountain basins. The basin is high in the west and low in the east, with an altitude of 2,500 to 3,000 meters above sea level, which is two to three times higher than that of the Tarim Basin, making it a plateau-type basin. From the edge of the basin to the center are, in order, the Gobi, hills, plains and lakes.
"Qaidam" means "salt marsh" in Mongolian. Two or three hundred million years ago it was a large lake, but as the western part of the basin rose, the surface of the lake gradually shrank, leaving more than 5,000 saltwater lakes. The Charkhan Salt Pond in the center of the basin is the largest salt lake in China, covering an area of about 1,600 square kilometers and storing 25 billion tons of salt, which can be consumed by the whole country for 8,000 years. The surface of the salt lake is covered with a large hard and deep salt cap, the thickest part of which reaches 15 meters. Through the basin of the north and south of the highway, there are 31 kilometers of road surface is built on the salt cover of the Charkhan Salt Lake; many houses here are also made of salt blocks. There are also colorful salt crystals on the basin, among which crystal salt blocks can be carved into various artworks. Qaidam is not only a world of salt, but also rich in oil, asbestos and various metal deposits, once known as the "Treasure Basin". Nowadays, this "treasure bowl", which has been sleeping for thousands of years, is being built into one of the important industrial bases in northwest China, and its eastern and southeastern parts have become newly reclaimed agricultural areas.
Sichuan Basin
Sichuan Basin is very different from the natural scenery of the three basins mentioned above, where the river flows all year round, the lush mountains, green fields set against the purple-red soil, red and green, making this basin known as the "Land of the Heavenly Creatures" look extraordinarily fertile.
Sichuan Basin is a hilly basin, an area of about 200,000 square kilometers, not only the form of integrity, but also a standard tectonic basin. Surrounded by Qionglai Mountain, Longmen Mountain, Daba Mountain, Wushan Mountain and Dalou Mountain, the altitude of 1,000 to 3,000 meters, more purplish-red sand shale, so there is a "purple basin", "red basin," the name. About 135 million years ago, the Sichuan Basin was a large inland lake. Later, due to crustal movement, the surrounding area rose into the mountains, the eastern edge of the Wushan Mountain topography is lower, the lake overflowed from the Wushan Mountain, the bottom of the lake gradually dried up into the basin. In the crust of the horizontal movement of the role of the basin mountain ranges are into the southwest - northeast direction, to the east of the highest terrain, the highest peak of the Huaying Mountains, about 1800 meters above sea level, becoming the highest point in the basin. The hills in the central part of the basin are gently undulating, accounting for almost more than half of the basin, forming a hilly basin.
The Chengdu Plain is located in the western part of the basin, which is a fan-shaped alluvial plain formed by the long-term accumulation of sediment entrained by the rivers and the continuous sinking of the earth's crust. It is the essence of the Sichuan Basin. 2200 years ago, the ancient Chinese working people built the famous Dujiangyan Water Conservancy Project in the Chengdu Plain, upstream of the Minjiang River, taking advantage of the topography of the area in order to prevent flooding and irrigation.
Dujiangyan is a large embankment built in the center of the Min River near Guixian County, which divides the river into an inner and an outer river. The tip of the weir at the front end of Dujiangyan is like the mouth of a fish, which is called the mouth of Dujiangyan. The water from the outer river rolls down and feeds into the Yangtze River. The water from the inner river is channeled into the Chengdu Plain through an artificially cut headland. This water diversion point is called "Baobingkou", and the rocky mound cut away from the bank is called "Liandu". In order to control the irrigation water, a flying sand weir was built between the inner and outer rivers at the downstream of Dujiangyan, so that all the water of the inner river could flow into the channel when the water was flat, and the excess water could be drained into the outer river over the flying sand weir when the water was high. After the completion of this project, millions of mu of farmland were irrigated, strongly promoting agricultural production in the Chengdu Plain. The working people also carved a water grid on the stone wall of Baobuikou to observe the changes in water level and accumulated a lot of valuable experience in water conservancy engineering.
Sichuan Basin, in addition to the alluvial soil of the Chengdu Plain, in the vast hilly areas, full of mountains are a purple-red soil. This soil is weathered from purplish-red sand shale and contains mineral nutrients such as phosphorus and potassium that plants need, making it one of the most fertile soils in southern China. However, due to the loose texture of this soil and the abundant precipitation in the basin, coupled with the hilly terrain, it is prone to soil erosion where vegetation protection is lacking. For a long time, the people of Sichuan in order to maintain soil and water to build a lot of terraces.
Sichuan Basin as a result of the experience of the land to the sea basin, from the sea basin to the lake basin, and then from the lake basin into the history of the land basin, so in the basin deposited rich deposits of coal, iron, salt, natural gas and petroleum, coupled with the basin's warm and humid climate, the intensive cultivation of fertile soil, making the reputation as the "land of the sky! Combined with the warm and humid climate in the basin and the fertile soil from intensive cultivation, the Sichuan Basin, known as the "Land of Heavenly Capital", is not only an important grain-producing area in China for rice, wheat and corn, but also produces sugarcane, cotton, silkworms, tea, oilseed rape, medicinal herbs and fruits. After the founding of New China, heavy industries such as iron and steel, machine building, chemical industry and many light industries have also developed rapidly here. Today, the Sichuan Basin is being built into an important modern industrial and agricultural production base in mainland China
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