Helan Mountain

Helan Mountain is 220 km long from north to South and 20-40 km wide from east to west. The southern part of the mountain is gentle and flat, and the northern part of the mountain to the north of sanguankou is higher, with an altitude of 2000-3000 meters. The main peak, also known as Helan Mountain, is 3556 meters above sea level. The mountain is asymmetric from east to west, with gentle slope in the West and fault in the east near Yinchuan plain. Helan Mountain is a strong earthquake zone. In 1739, an earthquake with M 8 occurred near Yinchuan. In 1561, an earthquake with m 7.5 occurred in Zhongning and in 1709 in Zhongwei. The northern part of Helan Mountain is rich in coal, and a new coal industrial base is built. Baotou Lanzhou railway has a branch line extending from Pingluo to Rujigou in Helan Mountain.

Helan Mountain

Helan Mountains are located at the junction of Ningxia Hui Autonomous Region and Inner Mongolia Autonomous Region, starting from Bayan Oboo in the north, maotukeng Oboo and Qingtongxia in the south. The mountains are majestic, like horses galloping. The horse is called "Helan" in Mongolian, so it's called Helan Mountain (it's doubted that this saying is wrong. Wei Chan in Tang Dynasty has a poem that "the orchard under Helan Mountain is completed". The Mongols rose only in the 13th century. It's just a common saying that it originated from Mongolian).

Helan Mountain is 220 km long from north to South and 20-40 km wide from east to west. The southern part of the mountain is gentle and flat, and the northern part of the mountain to the north of sanguankou is higher, with an altitude of 2000-3000 meters. Aobaogeda, the main peak, is 3556 meters above sea level. The mountain is asymmetric from east to west, with gentle slope in the West and fault in the east near Yinchuan plain. Helan Mountain is a strong earthquake zone. In 1739, an earthquake with M 8 occurred near Yinchuan. In 1561, an earthquake with m 7.5 occurred in Zhongning and in 1709 in Zhongwei. The northern part of Helan Mountain is rich in coal, and a new coal industrial base is built. Baotou Lanzhou railway has a branch line extending from Pingluo to Rujigou in Helan Mountain.

Geology and geomorphology

The altitude of Helan mountain ranges from 2000 to 3000 meters. The main peak of aobaogeda is located in the northwest of Yinchuan, with an altitude of 3556 meters. It is the highest peak in Ningxia and Inner Mongolia. The Helan Mountains, with a nearly north-south trend, stretch for more than 200 kilometers and a width of about 30 kilometers, are an important geographical boundary in Northwest China. The east side of the mountain is magnificent, with overlapping peaks and steep valleys. East overlooking the Yellow River Hetao and Ordos Plateau. On the west side of the mountain, the terrain is gentle and deep into the Alxa Plateau.

There are several East-West valleys in Helan Mountain. The famous ones are HELANKOU, Suyukou, sanguankou and baisikou, which have been the main traffic routes between East and West since ancient times. The scenic spots and historic sites of Xixia in the piedmont area are rich and colorful, including Xixia mausoleum, gunzhongkou, baisikou twin towers and unique Shahu scenic area. The southern end of Helan Mountain is Qingtongxia, which is bronze against the blue sky and Yellow River. It is said that when Dayu controlled the flood, he split the Helan Mountain and diverted the Yellow River to the north. Now there is Qingtongxia water control project. On the west side of Helan is BAYANHOT, an important town in Inner Mongolia, which is called "rich city" in Mongolian.

Helan Mountain is a rocky mountain with barren land and bare rocks. The vegetation type is simple and the vegetation coverage is low. The food provided for wild animals is very limited, which can not meet the rapid growth of wild animal population. In Helan Mountain, red deer and blue sheep like to eat shrub branches and herbs, such as Mallotus parvifolia, Spiraea, hazelnut, honeysuckle and so on. Due to the long-term grazing of wild animals, plant degradation and grassland desertification are caused.

Helan Mountain and NIUSHOUSHAN fold fault zone, Qingshuihe Liupanshan fold fault zone and Luoshan Yunwushan uplift zone form a series of anticline faults. In terms of landform, the west side of Helan is gentle, while the east side is steep and steep, with a large number of faults exposed to the surface. According to the statistics in 2010, the vertical drop between the east side and Yinchuan plain can reach 2000 meters. The northern part of Helan Mountain is mainly composed of granite. Because it is close to Wulanbuhe desert, it is dry and rainless, so the physical weathering is strong. The main body of Helan Mountain is in the middle of Helan Mountain. The mountain is steep, the mountain is huge, and the altitude is high, generally between 2000 and 3000 meters. The main peak of aobaogeda is in the middle of Helan Mountain, the altitude is 3555 meters, and the East-West width of the middle of Helan mountain can reach 50 kilometers. The southern part of Helan Mountain is relatively gentle. There are more than 50 gullies, such as Ruqigou, Dashuigou, xiaoshuigou, helangou, chaqigou, Suyukou and sanguankou gullies. The gullies are V-shaped, the lower part is wider, the bottom of the gullies is covered with gravel, and the gullies are generally alluvial fans with gravel.

The Helan Mountains are well developed with abundant fossils. From the Paleozoic to the Quaternary, most of the strata are complete, and only the deposits from late Yuetao to Early Carboniferous are missing. Precambrian Archean and Upper Proterozoic and gneissic schist quartzite are exposed in liutiaogou and dawukougou. The lower Paleozoic Cambrian limestone, sandstone and shale are well developed and commonly distributed. The upper Paleozoic is characterized by the same development of Carboniferous and Permian strata, which can be seen in Carboniferous wells, Suyukou, Shizuishan and other places, mainly composed of shale, sandstone and coal seams. Mesozoic Triassic strata are widely distributed, followed by Jurassic. The former is mainly composed of sandstone, conglomerate and shale, and the latter is mainly found in Rujigou, Gulaben and other places, mainly composed of various sandstones, and is one of the main coal producing strata in the mountain area. The Cretaceous and Tertiary strata are not developed. Quaternary alluvial proluvial deposits, aeolian deposits and piedmont deposits are widely distributed in the piedmont zone and Intermountain lowlands.

According to the terrain, it can be roughly divided into three sections: the north section is in the prime of life. High mountains and deep valleys, steep slopes and narrow watershed. North of the three pass. The middle section from Sanguan to yemaozi mountain is flat, with isolated mountains far away. It is the terrain of old age. To the south of yemaozi mountain, in the broad Pingdingshan, there are often narrow and deep valleys, which is another juvenile topography of erosion cycle. Most of the strata in Helan Mountain are of North China type, that is, the rock properties and fossils of the strata in different geological ages are completely the same as those in North China.

According to the statistics in 2010, the widest part of Dongpo mountain in the north section is 21km, with an altitude of no more than 2000m. It is mainly composed of granite, with a small amount of sedimentary rocks at the edge. The physical weathering is strong, forming a spherical weathering landform. The north part is close to Ulanbuh Desert.

The middle part is the main part of Helan Mountain, about 3000m above sea level, and the highest peak, shaguozhou, is located in the south of the middle part of this section. There are huge mountains, steep terrain, undulating peaks, steep rocks and deep valleys. There is a relatively gentle hillside above and below 2000m above sea level, with small gully depressions or Intermountain platforms, thick weathered materials on the hillside, and even small Intermountain ponding depressions. The east slope of the middle section is narrow in the South and wide in the north. According to the statistics in 2010, the widest part is 21km, with Suyukou as the boundary. The width to the south is less than 14km, and the mountain is gentle. To the north, the mountain is wider, generally more than 14km, and it can reach more than 20km to Rujigou. This is the Mesozoic stratigraphic development after the end of Paleozoic, with high-quality coal resources.

There are 21 gullies from sanguankou to kushuigou, which belong to the outflow area of the Yellow River system, the largest of which is Dawukou gully, with a catchment area of 574 square kilometers. Generally, the gully is deeply incised in the middle and upper parts, with a "V" shape. The lower part of the gully is relatively wide, with gravel all over the valley bottom.

The western slope of Helan Mountain is gentle, and gradually transits to the Inner Mongolia Plateau; the eastern slope is steep, the mountain is magnificent, and the height difference is large, forming a natural barrier, which weakens the Siberian high-pressure cold air, blocks the eastward invasion of the Tengger Desert, and also prevents the humid Southeast monsoon from moving westward. As a result, there are significant differences in climate, water source and vegetation between the East and west sides of Helan Mountain, and it becomes the outflow area of China The dividing line between temperate desert steppe and desert, monsoon climate and non monsoon climate, and also the dividing line between semi agricultural and semi pastoral areas and pastoral areas.

The geological history of Helan Mountain is as long as 2 billion years. The geological evolution of 2 billion years has not only made Helan Mountain from a vast ocean to a strange mountain, but also left many mineral resources.

In the Mesoproterozoic, about 1.55 billion years ago, the fault in Helanshan area was the sea, and the clastic rocks with a thickness of more than 10000 meters were deposited on the sea floor, forming the dominant mineral limestone in Helanshan. This kind of rock is dense and hard, and has the reputation of "Helan ridge". In addition, Helan stone, silica, and the oldest lower plant in Ningxia, micropaleozoite, are also products of that period.

In the Sinian period 700 million years ago, the oldest animal in Ningxia appeared in Helan Mountain area. It is not difficult to find such a worm fossil on the mountain road from Suyukou to Cherry Valley. Before the Sinian, Helan Mountain experienced the first ice age. At this time, the sea floor topography was rugged, the height difference was great, and the climate was cold. Therefore, glaciers developed at the foot of the mountain and formed a series of Sinian system related to glaciation.

After the end of the Sinian ice age, the climate began to warm and life began to flourish. Trilobites once dominated the whole ocean lived in that period. Transgression brought some dead marine organisms to the shallow sea. Phosphorus, an important organic substance in animal carcasses, combined with other substances to form phosphorus compounds. At that time, Suyukou area was a shallow sea, but the sea was turbulent, and the bodies of marine organisms were not firmly deposited in the stratum. This is the reason why the phosphate rock bed in Suyukou area is very thin and the reserves are limited.

Climatic characteristics

Helan Mountain is China

Chinese PinYin : He Lan Shan