How did Jiuzhaigou landscape come into being?

Jiuzhaigou is formed by karst dissolution.

Karst, originally a place name of Balkan Peninsula in Europe, is a limestone distribution area, and various peculiar landforms are formed due to the dissolution and erosion of limestone. Later, scientists used the word "karst" to refer to a series of address functions and geomorphological phenomena caused by chemical dissolution of limestone. In the subtropical region of South China, people mainly see the peak forest and peak cluster landscape eroded by limestone on the surface, and the redeposited stalactites can only be seen in underground caves with low temperature. However, in Jiuzhaigou, the annual surface temperature is much lower than that in the subtropical region of South China, and the erosion landscape of the surface is not very prominent. Except that there are many gullies and stone buds on the upstream surface, the erosion is mainly carried out underground. On the contrary, the most striking thing is the accumulation of travertine on the surface, forming travertine dikes, travertine pools, travertine beaches and travertine waterfalls. In the geographical environment of Jiuzhaigou, strong evaporation, the decrease of pressure after groundwater overflow, the increase of steep terrain velocity, especially the absorption of CO2 by aquatic plants during photosynthesis, are all conducive to the accumulation of travertine. The inverted karst landscape of this clock has become a masterpiece of nature.

Jiuzhaigou has all the favorable conditions for the development of karst dissolution: almost all the rocks in Jiuzhaigou are made of limestone, which is thousands of meters thick; Strong neotectonic activity has produced a large number of cracks and fissures in rocks, which has increased the water permeability of rocks; There is abundant precipitation in the basin, and the differential uplift of the plateau edge forms a huge topographic contrast, which is beneficial to the circular movement of karst water and the continuation of karst. Vegetation is developed in the basin, the soil is rich in CO2 and humic acid, and the rocks also contain organic matter and sulfur-containing minerals that can produce acidic substances, which provides a rich source of CO2 for groundwater and makes it have strong erosion ability.

The main manifestation of karst dissolution in Jiuzhaigou is the development of underground karst channels with objective scale. For example, there is no surface outlet in the long sea, and the lower section of Rizegou and Danzugou appears in the valley, all of which prove the existence of underground rivers.

Through water balance observation and isotope tracing research, it is confirmed that a considerable part of water in Changhai is replenished to Rizegou through underground rivers from Changhai to virgin forest and from Changhai to Yingzhaodong, making Rizegou a scenic spot with abundant water and the most concentrated Haizi in Jiuzhaigou.

In the world, the only karst scenic spot similar to Jiuzhaigou is Prithvi. The landscape scale and the complexity and diversity of ecological environment in Jiuzhaigou far exceed that in Prithvi. Prithvi Mining is located in the surrounding area of the Mediterranean Sea, with an altitude of 483m-637m；; Jiuzhaigou is located in the inland alpine valley area with an altitude of 2000 m-4700 m, and its karst function and landscape characteristics also have unique scientific value.