Topographic features of Hainan Island.
2. The mountains (mountains and hills) are wide and the plains are narrow, and the annular layered terrain consists of mountains, hills, terraces and plains.
Hainan Island is located at the southernmost tip of China, facing Guangdong across Qiongzhou Strait in the north and the vast South China Sea in the south. This is a typical tropical island.
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The islands in Hainan Province are divided into mainland islands and islands. Hainan Island was originally connected with Leizhou Peninsula in Guangdong Province. Later, due to crustal movement and seawater flooding, Qiongzhou Strait was formed, which separated it from the mainland and became a mainland island. Due to the comprehensive effects of submarine volcanic eruption and accumulation, coral reproduction and submarine sediment accumulation, the islands in the South China Sea belong to islands.
Hainan Island is a dome-shaped mountain with high middle and low sides. It consists of mountains (25.4%), hills (13.3%), terraced fields (32.6%) and plains (including terraced fields, 28.7%). The whole terrain descends step by step from the central mountain to the outside, from mountains, hills, platforms and plains, forming a layered vertical distribution zone and an annular horizontal distribution zone. Due to the influence of geological structure and tropical climate, landform development is characterized by obvious multi-layered landform, volcanic landform is developed, coastal accumulation plains are extensive, and coral reefs and mangrove coasts are the most typical in China. Tropical forestry belt with hills as the center, rubber hot zone with low hills as the center and tropical grain and oil crop belt with terrace plain as the center have been formed in production, which embodies the spatial combination of agricultural production and is deeply influenced by landform characteristics.
The mountainous area is represented by Wuzhishan, which is the symbol of Hainan Island. Due to long-term erosion and cutting, the five peaks are uneven and arranged in an east-west direction. The second highest elevation in the west is 1867. 1 m, which is the highest peak in Hainan Island. Next is the first peak, followed by the third, fourth and fifth peaks. Looking from a distance, it is magnificent and looks like five fingers, hence the name "Wuzhishan". The elevation of Ying Ge is 18 1 1.6 meters, which is the second highest peak in Hainan Island and the watershed of the three major water systems on the island. There are also the famous Bawangling, Jianfengling and Diaoluoshan. These mountainous areas are natural treasures of tropical virgin forests in our province and have high economic value.
In mountainous areas, there are also scattered hilly basins. The famous basins are Tongshi Basin, Yinggen Basin, Dongfang Basin and Ledong Basin, all of which are important bases for industrial and agricultural production in mountainous areas.
The hills are mainly distributed around the inland, northwest and southwest mountainous areas, with a relative height of 50 to 400 meters. The lower part of the hill has loose soil, deep soil layer, good drainage and quiet rheumatism, which is suitable for developing tropical crops.
Platforms and terraces are distributed around mountains and hills, with an elevation generally lower than 100m and a relative height lower than 80m, including lava platforms, granite platforms, red rock platforms, piedmont diluvial platforms, metamorphic rock platforms, river terraces and ocean terraces. The common landform of lava platform is volcanic cone, which is mostly distributed in the northern part of Hainan Island, Ma 'anling, Leihuling and Jiuzhou Ridge in Haifu area. Gaoshanling and Duowenling in Lingao County; Qingshan, Wenchang City; Nabiling and Bijialing in Danzhou City; Longmenling in Ding 'an County is a volcanic cone. Their earliest eruption history was about 6.5438+0 million years ago, and the latest eruption history was 30,000-50,000 years ago. The volcanic landforms in Hainan Island are well developed, with Ma 'anling crater as the most typical one, and the volcanic caves are extremely spectacular, which have been developed into famous tourist attractions.
Plains are mostly distributed in coastal areas around islands. Except in the south, some mountainous areas are close to the coast, including alluvial plain, marine plain, alluvial-marine plain, lagoon and sandy land, which are the main agricultural areas of the island. In terms of regional distribution, there are Wenchang marine plain in the north, Wangwu-Calais marine terrace plain in the northwest, Qionghai-Wanning coastal plain and Lingshui-Linlin coastal plain in the south, and Nanluo-Jiusuo coastal plain in the southwest.
The topography of the South China Sea Islands is characterized by small area and low terrain. Yongxing Island in Xisha Islands has a large area, accounting for 1.8 square kilometers, and the rest are below 1 square kilometers. The highest Shidao in Xisha Islands is only 12- 15 meters above sea level, and the rest are generally only 4-5 meters above sea level. In addition, there is a group of shoals-Shuibiao Island.