What landforms are there in the world?

Noun explanation: the state of surface fluctuation. According to its natural form, it can be divided into plateau, mountain, hill, plain and basin.

Detailed explanation of terms: surface ups and downs, such as mountains, plains, river valleys, sand dunes on land, submarine continental shelf, continental slope, abyssal plain, submarine mountains, etc. According to the size of the surface morphology, there are large landforms, medium landforms, small landforms and micro landforms. Continental and ocean basins are the largest geomorphic units on the earth's surface, and smaller geomorphic forms such as sand ridges and sand waves are formed under the action of running water and wind. Geomorphology is one of the important elements of natural geographical environment, which has a profound impact on other elements of geographical environment and human production and life. The landform is constantly developing and changing, and the material process of landform development and change is called landform process, including internal force process and external force process. Internal force and external force are two kinds of forces to shape landform, and landform is the product of the unity of opposites between internal force process and external force process. According to landform morphology and its genesis, landform can be divided into various morphological types, genetic types or morphological-genetic types. Geomorphology is also called geomorphology, but these two concepts are often different in use. For example, a topographic map generally refers to an ordinary map with a scale greater than 1: 1 10,000, focusing on reflecting the surface morphology, while a topographic map is a thematic map that mainly reflects the landform morphology-the cause or a certain landform element. In surveying and mapping, topography is the general name of surface undulation and ground features. The general trend of topographic relief is generally called topography.

(A) the basic characteristics of the landform outline

Under the influence of specific geological foundation, neotectonic movement and other internal factors, as well as complex and changeable external factors such as climate, hydrology and biology, the landform outline of China has the following basic characteristics; The terrain is high in the west and low in the east, showing a three-stage decline; The terrain is diverse, the mountains are vast, the mountains are vertical and horizontal, and the orientation is staggered into a grid. China's ethnic areas are almost connected, completely retaining the basic features of China's landform outline. The basic features of landforms in ethnic areas of China are:

1. The landform types are complex and diverse. There are plateaus and mountains raised by internal forces, low-lying basins and plains lowered by bending, and gentle hills. For example, many peaks in Hengduan Mountains are above 5000-6000 meters above sea level, generally around 4000 meters. Another example is the Turpan basin in the eastern Tianshan Mountains. Aiding Lake, the lowest part of the basin, is the lowest depression in China, with an altitude of-155m. Bogda Mountain in the north of the basin is 3500-4000m, and the highest Bogda Peak is 5445m, with a height difference of 5600m and a distance of only about150km.

There are desert and Gobi landforms dominated by wind in inland dry frog areas, accounting for about 13.8% of the national area, of which more than 95% are located in ethnic areas such as Inner Mongolia, Ningxia and Qinghai.

In the western mountainous area, the modern glacier area is 5.37 million square kilometers; Daxinganling, Qinghai-Tibet Plateau, Tianshan Mountain, Altai Mountain and Qilian Mountain, the frozen soil area is 210.5 million square kilometers.

Carbonate rocks are widely exposed in Guangxi, Guizhou and eastern Yunnan, accounting for about 42% of similar rocks in China. Under the hot and humid climate conditions, karst action is strong, and typical karst landforms have developed.

In the ethnic areas on the edge of the Loess Plateau, it starts from Huangshui River Basin in the west, passes through the foot of Liupanshan Mountain and Ordos Plateau, and reaches the vast area of Xiliaohe River Basin in the east. The accumulated loess is eroded by running water and developed into various modern loess landforms.

There are large areas of basalt erupting in Changbai Mountain, Daling, eastern Inner Mongolia Plateau, eastern Yunnan, western Guizhou and western Guangxi, forming lava landforms. For example, Tianchi at the top of Baitou Mountain is the crater lake; There are 348 extinct volcanoes in the northern and central parts of Xilin Gol League in Inner Mongolia. Red-bed hills are developed in southeastern Guizhou, central Guangxi, northwestern Guangxi and southeastern Guangxi, red-bed plateaus are developed in central Yunnan and red-bed mountains are developed in southern Yunnan.

Most provincial administrative units in Chinese mainland ethnic areas live inland, far from the sea, but Guangxi Zhuang Autonomous Region is close to the South China Sea and has a winding coastline of 1500 km. The famous bay is Qinzhou Bay, and the mudflats in the bay are mangrove coasts. The Beibu Gulf along the coast of Guangxi is located on the continental shelf, with a water depth of about 50 meters and more than 800 small islands, the largest of which is Weizhou Island. The islands of Qinzhou, Fangcheng and Dongxing Bay originally belonged to the eroded hills on land, but they were separated from the land by seawater intrusion and formed islands.

2. Mountain plateaus are widely distributed. About 93.5% of ethnic areas in China are located on the first and second steps. The main extremely high mountains (above 5000m above sea level) and high mountains (3500m-5000m above sea level) in China appear on the Qinghai-Tibet Plateau, the highest step in the west. The Qinghai-Tibet Plateau covers an area of 2.3 million square kilometers, accounting for 36.8% of the ethnic areas. On the Qinghai-Tibet Plateau, Mount Qomolangma on the border between China and Nepal is 8848. 13 meters above sea level, which is the highest mountain in the world.

The ethnic minority areas on the second step cover an area of more than 3.5 million square kilometers, accounting for 56.7% of the ethnic minority areas. This is the main Zhongshan Mountain outside the Qinling Mountains (elevation 1000-3500m). The eastern edge of the second step is roughly bounded by Daxing 'anling-Taihang Mountain-Wushan-Xuefeng Mountain line and the third step, and the altitude is mostly above 1500m. In addition to the central Qinghai-Tibet Plateau and the Loess Plateau, the Inner Mongolia Plateau, Yunnan-Guizhou Plateau and the northern edge of the Loess Plateau are all ethnic areas on the second step. In addition to Sichuan Basin, which is relatively low in elevation and small in area, Tarim Basin, Junggar Basin and Qaidam Basin are also in ethnic areas on the second step.

The mountainous areas in ethnic areas are concentrated and have a vast area. If the cut plateau and undulating hills are included, the vast mountainous areas account for about 75% of the total area of ethnic areas. Mountainous areas are the settlements of most ethnic minorities in China.

3. The plain is narrow and scattered. The plain area of ethnic minority areas on the third step is about 1 10000 square kilometers, accounting for 1.7% of the total area of ethnic minority areas. Among these plains, except for a large area in eastern Inner Mongolia, other ethnic areas are mainly scattered and narrow plains, most of which are plains with an altitude of 200-500 meters.

There are many small plains in Guangxi Zhuang Autonomous Region, covering an area of about 310.6 million square kilometers. The largest plain is Guiping, the alluvial plain of Yujiang Valley in Nanning, with an area of only 6,400 square kilometers. Generally, the plain covers an area of 300-600 square kilometers, with an altitude of 200-500 meters, and is separated from each other by mountains and hills.

In the hilly Yanbian Korean Autonomous Prefecture, Mudanjiang, Tumen and Hunchun rivers flow in the mountains, and in Yanji, Dunhua, Hunchun and other valley basins, narrow river alluvial plains with an altitude of 200-500 meters are formed.

(II) Main landform types

According to the classification of landforms, the land in China ethnic areas, like the whole country, is divided into mountains, plateaus, basins, hills and plains.

1. Mountain. China is a mountainous country, in which ethnic areas occupy most of our mountainous areas. According to the trend of mountains, they can be divided into the following types:

(1) There are mainly three east-west mountain ranges: the northernmost one is Tianshan Mountain-Yinshan Mountain, which is roughly located between 40 and 43 north latitude, and almost all of them are in ethnic areas. Tianshan Mountain Range is a huge mountain range in Central Asia, with a total length of 2,500 kilometers. Its western section is located in the former Soviet Union, and its eastern section is located in the middle of Xinjiang Uygur Autonomous Region, with a length of about 1500 km and a width of 250-300 km from north to south. Tianshan Mountain extends eastward, connects with Beishan Mountain (Heli Mountain and Longshou Mountain) on the north side of Hexi Corridor, and then extends eastward to central Inner Mongolia, which is the yinshan mountains.

The central pillar is Kunlun Mountain-Qinling Mountain, which is roughly located between 32.5 and 35 north latitude. Kunlun Mountain is located in ethnic areas, starting from Pamir Plateau in the west, east to the northwest edge of Sichuan Basin, and crossing Qinghai-Tibet Plateau from west to east, with a total length of about 2,500 kilometers. Jishi Mountain, a branch of East Kunlun Mountain, continues to extend eastward to Qinling Mountain, passing through the south of Shaanxi and eastward to Huaiyang Mountain, but the distribution of Qinling Mountain is no longer in ethnic areas.

The southernmost pillar is Nanling, located at 24-25.5 north latitude. Nanling, also known as Wuling, includes Yuechengling, Dupangling, Zhu Meng, Qitian and Dayuling, stretching from east to west 1000 km. Of the five mountains, the first three are located in the ethnic areas of southern Hunan and northern Guangxi, while the last two are absent.

(2) The mountains running from northeast to southwest are mainly distributed in the east of China, and are roughly divided into three rows from west to east. The westernmost column is Daxinganling, Taihang Mountain, Wushan Mountain, Wuling Mountain and Xuefeng Mountain. The central pillar includes Changbai Mountain, passing through Qian Shan in Liaodong and Shandong hills to Wuyishan in the southeast; The easternmost pillar is the mountain range of Taiwan Province Province. Daxinganling is located in the east of Inner Mongolia; Wuling Mountain is located in Xiangxi Tujia and Miao Autonomous Prefecture. Changbai Mountain is located in the northeast of China, and most of the mountainous areas belong to Yanbian Korean Autonomous Prefecture and Changbai Korean Autonomous County. Qianshan and Wuyishan are inhabited by Manchu and She nationalities respectively. Gaoshan people live in the mountainous areas of Taiwan Province Province.

(3) Northwest-Southeast mountain ranges are mainly distributed in western China, such as Altai Mountain and Qilian Mountain. Altai Mountain straddles the borders of China, the former Soviet Union and Mongolia. Located in Xinjiang, China, it is the south slope of the southeast section of the whole mountain system, with an altitude of about 3000 meters. Qilian Mountain crosses the northeast edge of Qinghai-Tibet Plateau, with a length of 1000 km from east to west and a width of 200-500 km from north to south. It consists of several parallel mountains and valleys, and the height of the mountains is generally above 4000 meters above sea level.

The mountains south of Kunlun Mountain, such as Karakorum Mountain, Gangdise Mountain and Himalaya Mountain, run northwest-southeast in the west and gradually turn east-west in the east. The Himalayan Mountains start from the Pamirs in the west and reach the sharp turn of the Yarlung Zangbo River in the east, with a total length of about 2,500 kilometers, stretching over Xizang Autonomous Region, Pakistan, India, Nepal, Sikkim, Bhutan and other countries. It is about 200 ~ 350 kilometers wide, and the average elevation of the main vein is over 6000 meters. It is the most majestic and steep mountain range in the world. There are 40 peaks above 7000 meters above sea level, including 8000 meters above sea level 12 peaks. It stands at the junction of China and Nepal, with a height of 8848.438+03m, which is the highest peak in the world. Chageli Peak in the Karakorum Mountains on the border between China and Pakistan is 86 1 1 m above sea level, which is the second highest peak in the world.

(4) The North-South Mountains are located in the ethnic areas in central China, including Helan Mountain, Liupanshan Mountain and Hengduan Mountain from north to south. Hengduan Mountain Range is located between Sichuan Basin, southern Tibet and Yunnan-Guizhou Plateau, and consists of many mountains and valleys alternately, including Qionglai Mountain, Daxueshan Mountain, Shaluli Mountain, Quiet Mountain, Nvshan Mountain and Gaoligong Mountain, as well as Dadu River, Yalong River, Jinsha River, Lancang River and Nujiang River. The average elevation of the ridge of Hengduan Mountains is about 3,000 ~ 4,000 meters, and some can reach 5,000 ~ 6,000 meters.

2. Plateau. Plateau is a relatively complete highland above 500 meters above sea level. The plateaus in China ethnic areas include Qinghai-Tibet Plateau, Inner Mongolia Plateau and Yunnan-Guizhou Plateau.

The Qinghai-Tibet Plateau is located in the southern foothills of Kunlun Mountain and Qilian Mountain, the northern foothills of Xilaya Mountain and the western section of Hengduan Mountain. It is about 3000 kilometers long from east to west and 1500 kilometers wide from north to south. The Qinghai-Tibet Plateau includes all of Tibet and Qinghai, and a part of Gansu, Sichuan and Xinjiang provinces, covering an area of about 2.3 million square kilometers, accounting for about 1/4 of the national area. It is the largest plateau in China. The Qinghai-Tibet Plateau is divided into many basins and wide valleys by criss-crossing mountains. The Qinghai-Tibet Plateau is dotted with lakes, which provides good conditions for the development of industry and agriculture. At the same time, the mountains on the plateau are covered with snow all year round, glaciers are widely distributed, glaciers and periglacial landforms are widely developed, and meltwater from snow and ice often becomes the birthplace of many rivers in Asia.

Inner Mongolia Plateau is located in the north of China, starting from Mazong Mountain in the west, reaching Qilian Mountain and Great Wall in the south and Daxinganling in the east. It is a famous natural pasture in China. The plateau is broad and open, and the ground is gentle and undulating. Most areas are about 1000 meters above sea level, which is a well-preserved plateau in China with obvious plateau morphology.

Yunnan-Guizhou Plateau is located in the southwest of China, including the areas to the east of Ailao Mountain, to the west of Xuefeng Mountain, to the south of Dalou Mountain and to the north of Beishan Mountain in Guangxi. Plateau topography inclines from northwest to southeast, with an average elevation of1000 ~ 2000m. Limestone is widely distributed in Yunnan-Guizhou Plateau, and karst landforms are well developed. Stone forest, stone bud and peak forest can be seen everywhere, especially in the northern part of Nanpanjiang River. There are many mountain basins on the plateau, which are called bazi by local people and are the main agricultural areas.

3. Basin. The basin is a relatively concave surface shape, which is lower than the surrounding mountains. Large basins in ethnic areas of China are all located in the northwest inland areas. The famous basins are Tarim Basin, Junggar Basin and Qaidam Basin.

Tarim Basin: Located between Tianshan Mountain, Kunlun Mountain and Pamir Plateau, surrounded by high mountains, the basin has a flat terrain and a complete diamond shape, and only the eastern end is connected with Hexi Corridor in Gansu Province, with a drop of about 70 kilometers wide. This is a huge inland basin. The east-west length of the basin is 1500 km, the north-south width is about 600 km, and the bottom area of the basin is 530,000 square kilometers. It is the largest inland basin in China. The basin is slightly inclined from west to east, with the altitude of 1300m in the west and Lop Nur in the east reduced to 768m. Because the basin is located in the deep inland, the terrain is closed, the climate is extremely dry, the vegetation is sparse, and the dry erosion, wind erosion and accumulated wind are particularly strong, forming the Taklimakan desert. The desert is 1000 km long from east to west, about 500 km wide from north to south and covers an area of about 330,000 square kilometers. It is the largest desert in China. There are all kinds of sand dunes in the desert, and the relative height of some deserts exceeds 200 meters. 85% belong to mobile sand dunes. Tarim basin is rich in oil, and the edge of the basin is moistened by melting water from Tianshan Mountain and Kunlun Mountain, and there are fertile oases in the desert.

Junggar Basin: Located between Tianshan Mountain and Altai Mountain, it is slightly triangular with an area of 380,000 square kilometers. It is the second great basin in China. The topography of the basin is slightly inclined from east to west, with the elevation above 1000m in the east and only 190m in the bottom of Ebinur Lake in the west. Kurban Tonggut Desert, with an area of 48,800 square kilometers, is the second largest desert in China. The grassland in the basin is vast and the animal husbandry is developed. Oasis is mainly distributed in the southern margin of the basin near Tianshan Mountain.

Qaidam basin is located in the northern part of Qinghai-Tibet Plateau, sandwiched between Kunlun Mountain, Altun Mountain and Qilian Mountain, and slightly triangular. The basin is about 850 kilometers long from east to west, 250 kilometers wide from north to south and covers an area of about 220,000 square kilometers, ranking third in the country. The Qaidam Basin is the largest inland high basin in China with an altitude of 2,600-3,000m. There are many salt lakes and marshes in the basin, and there are many kinds of salt resources with extremely rich reserves. In addition, nonferrous metals, ferrous metals, rare metal resources and petroleum resources are also rich; The basin has long sunshine time, abundant light energy resources, high output per unit area of agriculture, rich pasture along the river and lake, and animal husbandry also plays an important role. Therefore, Qaidam basin is called "cornucopia".

4. hills. The altitude in mountainous areas is below 500m, and the relative height is generally below100m. The terrain is undulating and the slope is gentle, so it is called hills. The hills in China ethnic areas mainly include Guangxi hills.

The hills in Guangxi are distributed in the areas east of Yunnan-Guizhou Plateau, south of Nanling Mountain and west of Mengzhuling Mountain, and together with the hills in the south of the Yangtze River and the southeast coastal hills, they constitute the most widely distributed and concentrated southeast hills in the southeast of China. The overall characteristics of hills in Guangxi are high around and low in the middle, forming a basin situation, which is generally called Guangxi basin. The hills in Guangxi are mainly limestone hills, and the limestone area accounts for about 60-70% of the local area. The karst landform is typical, the peak forest is widely distributed, the ground is rugged and the scenery is extremely beautiful. Guangxi hilly region is abundant in rainfall and heat, and it is a mountainous area with great potential for forestry, agriculture and mineral resources utilization.

5. simplicity. The plain is a vast land with low and flat terrain. According to the height of the plain, those with an altitude of 0-200m are called low plains, such as Yujiang-Jiang Xun Valley Plain. Inland lowlands below sea level are called depressions, such as the plain in the middle of Turpan basin in Xinjiang; A plain with an altitude of 200-500m (or 600m) is called high plains, such as the west bank plain of Nenjiang River in Inner Mongolia. Although the elevation of the second step and the first step in ethnic areas is 1000-3000m, they are customarily called plains instead of plateaus. Among them, Ningxia Plain and Hetao Plain are famous "granaries" which are alluvial from the Yellow River.

The plain, which is concentrated on the third step in China, is an important agricultural area and a densely populated and economically developed area in China. The plains distributed in ethnic areas on the third step are mainly concentrated in eastern Inner Mongolia and Guangxi. Although some plains here are small and undulating, they are still important agricultural areas in ethnic areas.

topography

The forms of surface undulation, such as mountains, plains, valleys and dunes on land, submarine continental shelf, continental slope, abyssal plains and submarine mountains, etc. According to the size of the surface morphology, there are large landforms, medium landforms, small landforms and micro landforms. Continental and ocean basins are the largest geomorphic units on the earth's surface, and smaller geomorphic forms such as sand ridges and sand waves are formed under the action of running water and wind. Geomorphology is one of the important elements of natural geographical environment, which has a profound impact on other elements of geographical environment and human production and life. The landform is constantly developing and changing, and the material process of landform development and change is called landform process, including internal force process and external force process. Internal force and external force are two kinds of forces to shape landform, and landform is the product of the unity of opposites between internal force process and external force process. According to landform morphology and its genesis, landform can be divided into various morphological types, genetic types or morphological-genetic types. Geomorphology is also called geomorphology, but these two concepts are often different in use. For example, a topographic map generally refers to an ordinary map with a scale greater than 1: 1 10,000, focusing on reflecting the surface morphology, while a topographic map is a thematic map that mainly reflects the landform morphology-the cause or a certain landform element. In surveying and mapping, topography is the general name of surface undulation and ground features. The general trend of topographic relief is generally called topography.

Terrain of China

China's terrain gradually inclines from northwest to southeast, with an altitude of 45-1480m and an average gradient of about 2%. It is mountainous in the northwest and hilly in the southeast. The mountainous area is mountainous and criss-crossed; The hills are undulating and the terrain is lower than that in the northwest.

geomorphic type

There are five main types:

Structural denudation-the low mountain terrain is located in the northwest of the county seat, and there are townships (towns) such as Cheche, Huanggang, Shuangfeng and tan shan. The lithology of the mountain is granite and Proterozoic Shuangjiaoshan Group shallow metamorphic rock series. There are many peaks in this area, with high mountains and dense forests, with an altitude of 500- 1400 meters. Due to erosion, the peaks are all arc-shaped, with a slope of 40 -50 degrees and a cutting depth of 200-500 meters. Dendritic gullies are developed, most gullies are U-shaped, most argillaceous rocks are V-shaped, and the vertical slope drop is about 15 -20 degrees.

Erosion and denudation of low mountains and hills is located in the northeast of the county, with Huaqiao, Tongan, Tianbao and other towns. This mountain consists of granite at an altitude of 200-500 meters. The hillside is gentle and the top of the mountain is round. Gully development, mountain depressions, small alluvial cones or alluvial fans are more common.

The central part of the county is hilly, including some areas of Fangxi, Qiaoxi, Tianbao, Aoqiao, Tang Cheng, Tangpu and Xinzhuang Township to the north of the highway line from Fangxi to Cunqian, with low structural erosion. The mountain forest is composed of Proterozoic shallow metamorphic rocks of Shuangjiaoshan Group, with an altitude of 200-500m. The slope of the hillside is 35 -40 degrees. Most of the peaks are pointed and the ditches are U-shaped. The terrain rises from east to west, the hillside becomes steep and the top of the mountain is steep. Vegetation gradually flourishes from east to west.

Tectonic denudation hills and hills are distributed in the south of the county seat, that is, the area south of Fangxi-Cunqian Highway, which is a part of Yifeng Basin. It is mainly composed of Cretaceous red sandstone and Permian limestone, with an altitude of 70- 150m. At most, the hills are steamed bread-shaped and table-shaped, with a slope angle of about 10 -20 degrees, and short and shallow valleys are common. Gravel hill is bare. In areas where sandstone and sedimentary rocks are distributed, the vegetation coverage rate is 30-50%. Vegetation in this area has been destroyed, soil has been eroded, and in some places topsoil has been lost and rocks have been exposed.

Valley accumulation topography is distributed in Shishi section of Jinjiang and its tributaries Xiye, Changchenggang and Tangpu River, forming terraces and valley landforms. The first terrace consists of Quaternary Holocene alluvium, with a layer width of 0.5- 1.5 km, flat terrain, slightly inclined to the river bed, 2-5 meters higher than the water level; The second terrace is mainly distributed in the tributary valley of Jinjiang, with a small area; The third terrace is distributed on both sides of the tributary of Jinjiang River. The terrace fluctuates about 0.5-2.5 meters, and the front edge of the terrace is steep. This area is the main grain producing area with deep soil layer and good water and fertilizer conditions.