Tuesday, June 19, 2018

Rainbow Mountain

          The Rainbow Mountains of China inside the Zhangye Danxia Landform Geological Park are a geographical wonder of the world. These well known Chinese mountains are known for their supernatural colours that copy a rainbow painted over the highest points of mountains. 

          This is only one illustration where geography attention our eye and makes one wonder: What makes the Rainbow Mountains be collared the way they are? Here I will talk about the digenetic and mineralogical forms that make up the reds, greens, yellows, and blues. 

         The Zhangye Danxia National Park is situated in the Gansu region in China's northwest covering 200 square miles. The site was named an UNESCO World Heritage Site in 2009 and is the goal for some Chinese and universal travelers. 

How Did The Rainbow Mountains Form?

          The Rainbow Mountains are cretaceous sandstones and siltstones that were stored in China before the Himalayan Mountains were shaped. The sand and silt was stored with iron and follow minerals that gave it the key fixing to frame the hues we see today. 

          What was previously a layered level and level stratigraphy was upset by the Indian Plate crashing into the Eurasian Plate around 55 million years prior. Much like when two autos get in a disaster area and the guards overlay and break, a comparable procedure collapsed what was once level sandstones into the Rainbow Mountains we see today. This procedure inspired mountains and uncovered sedimentary rocks that were generally concealed well underneath the surface of the earth. Weathering and disintegration expelled the overlying layers of mainland siliciclastic shakes and uncovered fundamental arrangements with various mineralogy and chemistry. This causes the striking variety in hues seen over the Rainbow Mountains. 

          Groundwater travels through the sandstone grains and stores follow minerals in the middle of the grains. This hasten can develop to a point where there is not any more a pore space between the individual grains, solidifying them set up. This procedure is the thing that grants the follow minerals specified underneath and takes into consideration the supernatural shading of sandstones around the world.

          The essential shading is dark red sandstone, similar to the Fountain Formation that outcrops in the Flatirons, Red Rocks Park, and the Garden of the Gods all in Colorado. The red shading is because of an iron oxide covering and cementation, between the sandstone grains. This is precisely the same that happens when a bit of metal is left out in the rain and structures a red layer of rust around the outside. 

          Weathering, blended with water and oxygen oxidizes natural iron into press oxide, which is outstanding for its dim red shading. The Rainbow Mountains are generally described by this iron oxide re-colouring of its sandstone Danxia formation. 

          Most of the time iron oxides impart a dark red pigment, however, there are instances where oxides form different colours. For example oxidized limonite or goethite will produce brown or yellow staining of sandstones; magnetite can form black staining of sandstones. If there is iron sulphide present, you will get a metallic yellow colour imparted by the sulphur. Meanwhile, green colouring is often due to chlorite or iron silicate clays. These are just some examples of how sandstones can be altered in colouring during digenesis. 

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