Limestone is a kind of carbonate rock mainly composed of calcite, Which is generally not very hard but can have a intense chemical reaction with dilute hydrochloric acid. Limstone is the major reason of forming karst landform in Donglan National Geopark, and it is also important raw materials for agriculture, industry, chemical industry and building trade.
Karst landform is a kind of landform developed in carbonate rocks, mainly composed of limestone and dolomite. Karst landform in China mainly distributed in Guangxi province, Guizhou province and east of Yunnan province, which is one of the largest karst areas in the world. The karst development of the Donglan region is characterized by multiple cycles and zonality, forming various features of karst landscape and wonderful cave scenes.
Water and Soluble rocks are necessary conditions in the formation of karst landform. When rainwater or underground water meet with carbonate rocks on the ground, few carbonate rocks will dissolve in the water. After a long time of dissolution and erosion, there formed karst landscape of various shapes in Donglan region. Besides, there also exist other landscapes, such as subterranean river and karst caves.
Sedimentary rocks have bedding characteristics. Climate changes changed the sedimentary environment, which in turn changes the size, shape, color and composition of the sediments. As a result, the bedding occurred. The common beddings are horizontal bedding, parallel bedding, inclined bedding etc. On the bedding plane, there are ripple marks, mud cracks, raindrop imprints and so on. Usually, there also exists biological fossils. Beddings, bedding features, and biological fossils are the main marks that differ sedimentary rocks from other rocks.
Bedding refers to the textures caused by the changes of composition, size, shape, color in vertical direction. Those textures usually can be seen in most sedimentary rocks and some magmatic rocks, which plays an essential role in studying geological structure deformation and its development. The stratification formed in sedimentary rocks could be due to the changes in sediment structure and composition or sedimentary intermittent and seasonal alternation. During the diagenetic process, influenced by gravity, particle size and wind, bedding of sorted behaviour was formed.
With the lamplight shining, the magic karst cave looks colorful and fantastic. Looking around, the exquisite stalactites are of various shapes, among which, some looks like chasing horses, others shaped like towering pagoda and fallen waterfall. What a vivid scenery with vitality! There are lots of karst caves in Donglan National Geopark, most of the representatives are Lenin rock, Lanmu underground palace, Xinyan cave, Banyi cave. etc.
Under the force of gravity, the rock and soil on the steep slope or on the roof suddenly drop, move and accumulate at the bottom of the valley or cave, forming a deposit of loose structure. The accumulation landform is formed after deposition.
Stalactite refers to carbonate deposits of various shapes, such as stalactite, stalagmite and stela, which is formed under the deposition of calcium carbonate and other mineral substance in the cave of carbonate area under specific geological conditions during the long geological history. The stalactites in the karst caves of Donglan National Geopark are vivid and of various shapes . Stalagmites shaped like a sharp sword, which standupright against the sky; Columns shaped like giant columns, which are magnificant. All of those are the uncanny workmanship of nature, which is really amazing and wonderful.
Joint refers to the crack caused by rock stress, with no obvious displacement on both sides of the parting plane. Joints can be seen everywhere on rock outcrops. According to the cause of formation, joints can be divided into two categories: primary joints and secondary joints, the former refers to the joint formed during diagenetic process, while the latter refers to that formed after diagenesis.
Rimstone dam is a landform shaped like terraced fields, which is formed after a rapid deposition of a large number of crystalline travertinein a sloping field or valley. In the bulge, the velocity of laminar flow quickens, as a result, the partial pressure of carbon dioxide decreases and overflows, resulting in calcium carbonate deposition near the bulge. Looking ahead, it looks like terraced fields.
Lenin rock is a natural karst cave shaped like a hall, which was formed by underground water erosion to the mountain in early stage and was later exposed to the surface by the crust uplift. It is a former site used for preaching place when the Guangxi Peasant Uprising took place. When approaching towards it, you can fell the thick breath of revolution. In Mar. 1922, WeiBaQun gathered the Revolutionary League and set up the 1st preaching place for Peasant Uprising in this cave together with Chen Bomin and others to promote Marxism-Leninism, which has laid a solid mass base in creating the Youjiang Revolutionary Base.
Karst cave is formed in the cave where dissolution develops and it is an open residual cave passage that has been separated from the underground water level and was hanged above the top of the mountain. On the cave wall, there exists notch, flow mark, flute and other shapes. The body of the cave shaped like a channel, which is a typical form of fluvial karst. There are a large number of karst caves in Donglan National Geopark,such as famous Tianbaoshan and Moon mountain karst cave.