Lishan Sub-geopark of Rift and Horst Structures     The Lishan sub-geopark of rift and horst structures covers an area of 63.23 km2. Geological heritage sites in the sub-geopark include escarpment, shattered fault zone, fault breccia and cataclasite that were formed with the formation of the Lishan mountain, stratigraphic sections of the Neogene and the Quaternary system, the Proterozoic complex breccia, the Jurassic conglomerate of fluvial facies and plane of unconformity as well as hot springs.     The Lishan Mountain started upwarping in the late of the Yanshanian period, forming an isolated horst-block mountain in the Weihe graben zone. In the neotectonic period, the whole Lishan block uplifted and activated at northward upwarping and southward downwarping, forming a block with an appearance of higher in north and lower in south.     The area of Lishan Mountain is one of famous tourist resorts in China. In retrospect, Lishan Mountain was densely covered with towering pines and green cypresses. Mt. Lishan has been an amusement park for imperial families and a tourist attraction sine the West Zhou Dynasty (1046 B.C.) of ancient China. The “Remonstration Pavilion” on Mt. Lishan is also famous for telling us the story about the Xi’an Incident that took place in Dec. 12, 1936. Lishan Mountain is representative with splendid landscapes, a long history of imperial paradises, natural hot springs, abundant geoheritage sites, cultural relics and historical heritage sites. Therefore, it was officially nominated as one of the key famous attractions in China by the State Council of China in 1982.     Geological section of the Weihe graben     The Lishan Mountain started upwarping in the Late of the Yanshanian period, forming an isolated horst-block mountain in the Weihe graben zone. In the neotectonic period (65 million years), the whole Lishan block uplifted and tilted at northward upwarping and southward downwarping, forming a block with an appearance higher in the north and lower in the south.     Faults adjacent to Lishan Mountain are named the Mudangou Fault and the Lishan North Marginal Fault. The Lishan North Marginal Fault illustrated a clear evidence of tectonics in the Quaternary era. For instance, two times of earthquakes are recorded occurring at magnitudes of 6.5 and 5.5 along the fault in 1478 and 1568 respectively. Along the fault plane, landslides took place. Ground fissures are well developed along the fault and cut gullies in some places, which demonstrates a sinistral shearing of the fault. Fault movement caused the Lishan host uplifted continuously and corroded the bed of the Weihe River and moved it northward, averaging 1.98m a year. Spring spots occur along the fault and many thermal springs are in relation to the fault in the area of the Huaqing Pool. The geothermal anomalies have also indicated the current activities of the fault.     Hot spring means that ground water issuing from an artesian spring rises to a higher elevation than the top of the confined aquifer from which it issues. Springs are often classified by the chemical components, temperature, acidity and alkalinity of the water they discharge.     A thermal spring having water warmer than 98°F (37°C) is usually heated by emanation from or passage near hot or molten rock. Hot springs are formed when rain and other surface waters drain through faults or crack in the Earth's surface and reach hot rocks -- those found at the bottom of deep chambers, or volcanically heated material closer to the surface. When the water is heated to boiling, it rises, and if it can find a crack or fault to the surface, it will emerge as a hot spring. En route, the water often picks up a host of minerals, such as sulfur, silica, calcium, potassium, ammonia and phosphate. This may give the water flavor and even carbon dioxide bubbles, depending upon the nature of the geology through which it passes. This is why spring water is often bottled and sold as mineral water. Springs that contain significant amounts of minerals are sometimes called 'mineral springs'.     Geothermal resources are abundant along the fault zones in this area. The natural outcrops of hot springs mainly present along the piedmont fault of Qinling Mountains, in which the well-known hot spring is situated in the Huaqing pool at the foot of Mt. Lishan. The hot spring occurring in the Huaqing pool has a temperature up to 43?C and a circulation depth 982m. According to historic records, the geothermal water in this area has begun to be used since the Zhou Dynasty (1046 B.C. -256 B.C.), and from that time, the imperial palaces and gardens begun to be built at the foot of Mt. Lishan specially for royal families to take hot baths and entertain themselves.     This area displays exceptionally strong links between its landscape and social history. One of the most celebrated poets in the late of the Tang Dynasty of China, Bai Juyi (772-846 A.D.), was inspired by the landscape here and wrote his famous poem, “A Song of Eternal Sorrow”, narrating an emperor’s love story occurring in this area.     A normal fault presents in the north side of the Lishan fault block, which strikes to approximately east-west and dips to north. The heritage of deformation by tectonics, the indicators of landform and the Cenozoic sediments in the fault zone indicates that the tilt and extensional movements have been in active under regional extensional stress since the late of the Quaternary period. In the long-term tectonic movement, creeping and stick-slip are dominant. At present, the fault is still in active.     The foot wall of the fault consists of plagioclase schist of the Archeozoic Taihua Group and the hanging wall is the red-colored mudstone of the Neogene and the Quaternary loess. Along this fault zone, the Lishan fault block rose up and left behind the big escarpment at the place of “the Remonstration Pavilion”, which was cut by another fault striking in approximate south-north direction.     At the west side of the valley, many normal faults are present in the hanging wall, forming bench-like patterns.      At the east side of the valley, three sets of strata occur in the hanging wall. In the lower portion, the Neogene red mudstone occurs with sandstone at almost parallel beddings, in which bench-like normal faults are developed. In the middle portion, the Lower-middle Pleistocene conglomerate consists of nonstratified slope deposits, covering on the strata below at unconformity contact. In the upper portion, strata are the Middle Pleistoncene-Holocene loess, covering on the strata below.     In the east side of the valley, the neotectonic massif is visible. The calcareous layers in the Neogene red-colored mudstone is representative with displacement blocks formed by shearing at different directions and fracturing. The shearing surfaces are clearly visible, which is the heritage of tectonics in the Quaternary period.     The remonstration pavilion was built for remembering the Xi’an incident where Chiang Kai-shek, the president of China in 1936, was arrested when the Japanese imperialists were intensifying their invasion of China. Instead of fighting the invaders, Chiang Kai-shek flew to Xi’an to plan his military campaign against Yan’an then center of China’s revolution in December 1936. From his resort suite at the Huaqing Pool he ordered the suppression of a 10,000 strong patriotic student demonstration. Two of his generals, Zhang Xueliang and Yan Hucheng, were reluctant to carry out his orders and tried to persuade Chiang to accept the proposal of forming a national united front for resistance. When that failed, they decided to arrest him.     At dawn on December 12, 1936, troops commanded by Zhang and Yang arrived at Huaqing Pool to capture Chiang Kai-shek. Hearing gunshots, Chiang fled without taking time to dress and scrambled up Lishan Mountain, only to be caught cowering in a rock crevice halfway up the slope.     Aoon after, a delegation headed by Zhou Enlai, one of the important leaders of Communist Party of China at that time, was set to Xi’an at the invitation by Mr. Zhang and Mr. Yang. Zhou Enlai and his delegate did a lot of work there and took everything possible into consideration. Ultimately Chiang was forced to accept the proposal made by his two generals. On December 25, Chinag was released, and flew to Nanjing City, the capital city of China at that time. Consequently the Xi’an Incident was settled peacefully and marked a turning point in the history of China.     In March 1946, based on an initiative of Mr. Hu Zongnan, a famous general at that time, all noncommissioned officers of the seventh branch campus affiliated with the Huangpu Military Academy raised contribution for building a pavilion near the crevice where Chiang Kai-shek had hidden himself during the incident and named it the “Justice Pavilion”. It was built by stone with a height of 4 meters and a width of 2.5 meters. In 1949, the local people started to call it the “Catching Chiang Pavilion”. Since December 1986, the pavilion has been renamed as “the Armed Remonstration Pavilion”. Iron chains and rings are available all the way up to the crevice cast of the pavilion, by which visitors can climb up to take a look at Chiang Kai-shek’s shelter.     In ancient times, a signal fire beacon was usually built on a high hill, which gave a signal fire that can be seen from a distance for warning of an enemy’s approach.     Located on the Xixiu Ridge of Lishan Hill, the remains of a signal fire beacon built in the Western Zhou Dynasty (1066-771 B.C.) is easily identified. The King named You of the Western Zhou Dynasty had a palace built in the area near the Huaging Pool. He built a signal fire beacon on the top of Lishan Hill for making fun of his feudal lord in other ducal states to make Bao Si, his beloved lady, smile. As a result, when his opponent attack was true, the fire signal for help from the beacon couldn’t call up his troops from his feudal lord. Then the Western Zhou Dynasty was over thrown and the King was killed. Hence, there is a Chinese allusion saying the story by “Baiting feudal lord with signal fire costs a whole country for a smile”.     Mudangou Fault, with a strike to approximately north-south and a dip to west, is the west margin of the Lishan horst