Cuihuashan collapse-slide scenic area is a part of the Cuihuashan collapse-slide sub-geopark. It covers an area of 99.81 km2 and is featured in landform of mountain collapse-slide. It is peculiar for its complete types of mountain collapse-slide, typical structures, intact preservation and huge scale in home and abroad.     The major body of the Cuihuashan mountain collapse-slide occurred in multiple phases 2,787 years ago. The heritage sites of mountain collapse-slide in Cuihuashan are characterized by: (1) the quantity of the mountain collapse-slide is huge, which is the largest one in China and the third largest in the world, following the USOI mountain slide in Tajikistan and the Waikaremoana mountain slide in New Zealand; (2) the size of individual collapse-slide stone is the biggest in Mt. Chuihuashan, generally 103-104m3 and contrasting to other records about mountain slides in the world, individual sizes of slide stones are generally several meters, maximum 10-20m3; (3) the geomorphic patterns of mountain slide in Cuihuashan mountain include barrier lakes, barrier dams, stone sea, concentrated distribution of sliding and freeing surfaces; (4) it boasts a long history for its age over 2,787 years; (5) the convenient access to the heritage sites of mountain slides, easily to be administrated for protection and development.     Cuihuashan Scenic area is located in the medium-low mountainous area, 4 kilometers to the northern piedmont fault of Qinling Mountains. The fault has a long history of activities and is still in active up to date. The north side of the fault subsided and formed the Guanzhong plain (the Weihe basin) and the south side uplifted to form the lofty Qinling Mountains.     Geological evolution in the Cuihuashan scenic area took place in company with the development of the Qinling orogenics. Stratigraphy in this area includes the Early Paleozoic Erlangping Formation, about 480 million years old. During that time, the area of Cuihuashan was a marginal sea covered by a broad seawater, in the north side of which was the continental shelf of the North China Plate and the south side was the old island chain (island-arc) that trended to the west-east direction, in which volcanic deposits and sediments of back-arc basins occurred in the marginal sea. During the time between 400-250 million years, underthrusting and collision between the North China Plate and the Yangtze Plate had closed the sea basin in the Cuihuashan area, from which the sea water retreated, the accumulates inside experienced extensive deformation and metamorphism, various migmatites were formed by migmatitization and frequent granitic intrusions took place. From the time of 130 million years, when strong tectonic underthrusting, orogenics and magmatic activities occurred in the area of Cuihuashan, the buried rocks rose up and formed the rudiments of Cuihuashan Mountain. Since the Cenozoic era (about 65 million years), the faults occurring in this area took actives many times, having the rocks here broken and fractured and the Cuihuashan Peak upheaval. Then earthquakes took place here for years and resulted in mountain collapse-slide, leaving behind abundant geological heritage on mountain collapse-slide and miraculous landscapes. The selected geotourism itinerary in the Cuihuashan scenic area demonstrates the geological heritage sites of mountain collapse-slide to the visitors. It has a length of 8 kilometers, containing 102 geoheritage sites. This time we are going to visit 6 of those geoheritage sites.     The geological heritage sites in the Mt. Cuihuashan collapse-slide scenic area are mainly represented with collapse bluffs, barrier lakes, barrier dams and stone sea, occupying a total area of 5.2km2 and containing a total quantity of collapsed rocks about 300,000,000 m3. It is the largest one in China and ranks third in the world. The freeing surfaces resulted from rock collapse are present in residual peaks, scarps and precipices, generally 100-250m high. The sliding rock masses were kept well and featured in complete and huge sizes, forming the barrier dams and the barrier lakes; the collapsed rock masses with different sizes accumulated in valleys, thus forming a splendid stone sea, in which mutual superimposed huge stones, accumulation and mutual support constitute the narrow fissures and caves. In this place, the Weihe plain is visible to the visitors. Tectonic movement featured in northern overthrusting and southern underthrusting of the Qinling orogenic zone has resulted in the huge height difference of 2,000-3,000 meters between the Weihe plain and Qinling Mountains.     The river valley in front of us is the Taiyi River Valley. A V-shaped narrow valley was formed by mountain rising up and river incising downward, which is representative of valleys in the north side of Qinling Mountains. Both the sides of the Taiyi Valley are featured in escarpment.     There are three faults visible in the escarpment on the left, where a leveling mark has been set up for periodic leveling surveying.     The major body formed by collapsed rocks (barrier dam) is on the right side of us, which contains collapsed rocks with a large size in diameter ranging between 3-5 meters. Opposite to the traffic road is the major scenic spot of the collapsed rocks (avalanche debris cone and stone sea).     The barrier dam of Cuihuashan Mountain has a height 150 m, a length 600 m and a width 300m, which blocked the Taiyi River and formed a barrier lake at the top. The accumulation of collapsed rocks in front of us is the major part of the dam. It has a slope angle of 40 degrees, in which a path for climbing on foot runs zigzag up to the top of the dam. Another new trail for climbing is under planning, where plantation is thick and environment is quite peace.     On the left side of the place where we are standing is the residual collapsed surfaces formed by mountain collapse-slide in different periods. The smooth escarpment above the channel was formed in the first phase and along the strike, it is cut through by another escarpment that is opposite to us and formed in the second phase.     The stone sea (accumulation of collapsed rocks) is the major scenic spot, which was formed in the second phase of mountain collapse-slide. It is the major attraction of the landscapes of the Cunihuashan mountain collapse-slide. Since 2000, a program of protection and development of the area has begun for its abundant collapsed-slide rocks in various sizes, in which individual collapsed rocks are huge in size, ranging between 10 and 100 meters in diameter with a volume generally over 1,000 cubic meters. The landscapes formed by collapse-slide rocks is claimed to be a museum of mountain collapse-slide with miraculous postures of collapsed stones.     The windy cave was formed by two huge stones mutually propping up as an inverted V-shaped pattern with a long and narrow air passage. It is 40 meters long, 15 meters high and 2-2.5 meters wide.     In the windy cave, funneling of air makes air ventilation inside and especially in summer, it would make you feel windy inside the windy cave because of a great difference of temperatures inside and outside the windy cave.     The icy cave is about 120 meters long, which is tortuous and goes down to underground. It consists of irregularly massive rocks that propped up and superimposed each other. Since the floor of the icy cave is lower and there is no sunshine inside in the whole year, the temperature inside the icy cave keeps cold all the time. According to historic records, the imperial family often fetched ice in summer season during ancient times in China.     On the top of Cuihua Peak, landscapes of collapsed faces, residual peaks and accumulation of stones formed by mountain collapse-slide are clearly visible to visitors.     The dominant collapsed faces are formed by two phases, the first of which strikes to 60°and the second 150°, showing the movement directions of two events of mountain collapse-slide are approximately perpendicular each other.     The accumulation of collapsed stones formed in the second phase of mountain collapse-slide is the largest in size, forming a stone sea in this scenic area. The accumulation of collapsed stones adjacent to the collapsed surfaces is smaller in size, which formed later and has a clear boundary with the earlier accumulation of collapsed stones in the east.     The heritage of mountain collapse-slide in the scenic area is the largest and most extensive in the Ganqiuchi area. In the early phase of mountain collapse-slide, sliding of basement rocks was dominant and collapsing was secondary. The total quantity of collapsed rocks is about 180 million cubic meters, in which the landscapes of collapse-slide are preserved completely, including barrier dams, barrier lakes, freeing surfaces of basement rock, avalanche debris cone, zones of creeping rubbles and sliding bodies.      To southwest, the barrier dam burst and collapsed with flooding and had been almost leveled, leaving behind some sparsely distributed residual rocks of mountain collapse-slide.     The barrier lake on Cuihuashan Mountain is named the Tianchi Lake (the Sky Lake) and also called the Shuiqiuchi Lake, which is shaped like a fusiform with a length about 600 m, a width ranging between 90 and 300m, and a depth ranging between 7m and 11m, occupying an area of 135,000 m2. A Barrier dam that was formed by collapsed rocks blocked the natural drainage (the Taiyi River) and created the large lake (the Tianchi Lake) behind the dam.