Cave Dwelling
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Cave Dwellings (Yaodong)
Dwelling caves are very common in the Loess Plateau in north-west China, and are actually homes to millions of people. By creatively making full use of the plateaus, the intelligent people of the present Shaanxi, Gansu and Ningxia provinces have built dwelling caves since ancient times, and these dwelling caves are among the key features of north-west China. The basic desire of farmers in north-west China was to dig a dwelling cave, so that they could get married and raise a family, and the women were supposed to manage household affairs and bring up their children in the cave. History of the Dwelling Caves The dwelling caves are a famous name card of the north Shaanxi area (geographically referring to the area south of the Great Wall, west of Yellow River, east of the Ziwuling Peaks and north of the Qiaoshan Mountains), with a long history of over 4,000 years. Two ancient stone cities, built in the late Neolithic Age, were discovered successively by archaeologists in Wubao County of Shaanxi Province in 2004, where over 70 dwelling-cave-style remains have been found. According to archaeological findings, the dwelling caves of the north Shaanxi area were semi-subterranean caves in the Zhou Dynasty (1046 BC-221 BC), which evolved into subterranean caves in the Qin (221 BC-206 BC) and Han (206 BC-23 AD) dynasties. Stones were used to build the facades of dwelling caves in the middle period of the Ming Dynasty (1368-1644). Stone-structured dwelling caves were built, modeled on the earthen dwelling caves, in the late Qing Dynasty (1644-1911). The dwelling caves have become more and more comfortable to live in now owing to new modern facilities which have been added to them. Classification of the Dwelling Caves Dwelling caves are divided into three types: cliffside caves, sunken caves and detached caves. A cliffside cave is excavated out of the side of a cliff and more often than not faces south; a sunken cave is actually a large sunken courtyard that’s as large as 100 square meters; a detached cave is an earth sheltered building. Characteristics of the Dwelling Caves The dwelling caves are cool in summer and warm in winter. A traditional dwelling cave is square-shaped with an arch on the facade, which not only symbolizes the idea of a circular heaven and square earth, but its large arch-shaped window allows sunshine to pour in, making it very cozy to live in. Geographical Distribution of the Dwelling Caves Dwelling caves are widely distributed in China, ranging from Xinjiang Province (Turpan and Kashkar) to Gansu Province (Lanzhou, Dunhuang, Pingliang, Qingyang and Gannan) to Ningxia Province (Yinchuan and Guyuan) to Shaanxi Province (Qian County and Yan’an) to Shanxi Province (Linfen, Fushan, Pinglu and Taiyuan) to Henan Province (Zhengzhou and Luoyang) to Fujian Province (Longyan and Yongding) and to Guangdong Province (Mei County), with Shaanxi dwelling caves being the most famous in China. Shaanxi dwelling caves are built along the vast Loess Plateau, which is characterized by its beauty and energy-saving attributes. According to the preliminary statistics, the number of dwelling caves in China has reached over 110 million from 1949 to now, many of which collapse each year owing to exposure to floods and mudslides. Dwelling Cave Culture Qingyang is the cradle of the Chinese farming culture; it is located in the east of Gansu Province with a moderate climate, and it’s also where the dwelling caves originated. After thousands of years, the dwelling caves still stand silently in the vast land of China, witnessing the development of China’s farming culture. The primitive men used to live in the natural caves that were dark and humid, which were very bad for their health, and they were often attacked by wild beasts. The people of the Zhou Dynasty dug caves out of the mountains to live in, which provided shelter for them and protected them from wild beasts, and the ancient people began to settle down. As great progress was made in agriculture, the dwelling caves served as homes for the ancient people who later created a prosperous farming culture in the history of China.
China's Cave Dwellers
YANAN, China, June 22, 2005 - While environmentalists in the West are still scratching their heads for answers to energy-efficient, eco-friendly living, some Chinese have had the solution for thousands of years - cave dwelling. Whereas cave dwelling in the West conjures up images of prehistoric men, for many millions in parts of China it is just a matter of tradition, and sheer common sense. Besides, these days cave homes come equipped with all mod-cons such as cookers and refrigerators and are even wired for cable TV. "Yaodong", as cave homes are known here, can be found mostly on the vast loess plateau of northern China where the unique soft, yellow earth in the mountains is not only easy to dig but so tightly packed that it holds together without any built support. Throughout dry and mountaineous northern China, an estimated 40 million Chinese still live in caves or subterranean dwellings. For these people, there is nothing more natural and ordinary than to live in the dugouts: their homes are easy and cheap to construct, warm in winter and cool in summer, and shield them well away from the strong winds and harsh weather. In the new fast-living era, Chinese people love anything modern from flash cars and mobile phones to digital cameras. But cave-dwelling is one thing that the people of Shaanxi province swear they will never give up on their road to modernisation. Most people in this former communist revolutionary base of Yanan have lived in a cave at some time in their lives, and even for those who now live in modern flats, they still say they miss cave-dwelling. By a hillside not far from a 1930s communist guerilla army base lives Zhang Xiaoqun, a construction worker, and his family. Their humble cave house is simply dug into the side of a hill with a facade coated with bricks but is wired with an electrical supply and cable television. In the 70 square meter (753 square feet) space under arched ceilings, he and his wife sleep, watch television, cook and have family dinners with their grown-up children, who live in a cave home further up the hill. "The advantage of a cave is that it is cool in the summer and warm in the winter," he says. "There is no need for fans or air-conditioning in the summer, although it can get a little damp after it rains." One very practical advantage of cave-dwelling, Zhang says, is that rents are relatively cheap. Zhang, who earns just 500 yuan (60 dollars) a month when work is available, pays a monthly rent of 110 yuan (13 dollars) -- less than half that of conventional flats in central Yanan. Utility bills are also less, with no air conditioning and less heating costs. Although the temperature in Shaanxi can drop to as low as minus 20 degrees centigrade in the winter, the natural insulation of the earth can keep temperatures in the cave at a constant 10 degrees with the help of a "kang," a huge stone bed that is linked to an indoor stove warmed by the heat of cooking. For others, cave dwelling is a matter of emotional attachment. "Of course I prefer living in a cave. I don't know how to explain it, it just doesn't feel quite right in an ordinary flat," says taxi driver Tian Ping. Standing by a well dug by guerilla communist soldiers in the 1930s, Liu Chaoying, 46, a folk singer and dancer who lives in a modern flat in central Yanan, talks fondly of the peace and traquillity of cave-dwelling in the hills. "Caves are more primitive, but the air is nice and fresh by the hillside," Liu says. "People in town, when you close your front door then you don't talk to your neighbours. There, people sit outside and eat, you chat with your neighbours, your children play together, it's a much more friendly setting." Shaanxi people's pride in its heritage can be seen manifested in Yanan city's cave-inspired architectural style, from shops and garages to a recently-completed government-subsidised housing estate for low-income families where ordinary buildings they are shaped like caves. Lu Hai, 70, who lives in one of the 698 cave-shaped teracced houses on a hill slope at Dongsheng Gardens -- touted as the biggest group of caves in the world -- said the modern design is much more civilised than the traditional earthen dwellings, where he lived until recently. "These brick built caves are good, they are much harder wearing than the old ones. These caves have kitchen and toilets indoors, they have central heating, that's much better," he says. His neighbour a woman surnamed Guo, 54, however feels no romantic nostalgia looking back to her days of living in earthen caves. "People had no choice when they were poor, now people are well off, there is no need for people to huddle together on top of the brick stove with all their family," she says. "You needed to chop firewood and all that -- it wasn't all fun." But architecture professor Wang Jun at the Xian University of Architecture and Technology says that with suitable renovation and improvement, such as ventilation, even traditional earthen caves can be as comfortable as modern houses. He believes that the durability of caves combined with their energy efficient characteristics mean that caves will not only last into future decades, but will even spread in popularity in a new eco-conscious era. "Now it has become a trend, people want eco-living and they find that cave dwelling is actually very environmentally friendly," he says. Not only do caves save space by being cut into hill terraces, they also save arable land since they use non-fertile or hard-to-farm hillsides, and also reduce use of China's hard-pressed energy supplies. "Modern living is often not eco-friendly and sacrifices people's health with harmful building materials and paints," says Wang. Many Western environmentalists are also keen on cave-dwelling, saying that the natural insulation of the earth makes for high energy efficiency and provides a perfect method for the creation of eco-friendly accomodation. In one earth-sheltered housing project monitored by the University of Bath in Britain, it was found that the underground design used only 25 percent of the energy that would be required by a standard house on the same site. Wang is confident that even though more rural Chinese people are migrating to cities, cave dwelling will remain a much-loved tradition of habitation for many years. "In the past, local officials' political achievement was measured by how many people they manage to move out of the caves, but now many have got to know the value and attraction of caves," he says. "The caves won't disappear, there are simply too many advantages." Taxi driver Tian Ping can attest to that. "When I retire, of course I'll go back to my home village and live in a cave, there is no question about that," he says.
Cave-Dwelling "Slime Curtains" Cycle Nitrogen and Iron
In 2009 geomicrobiologist Jennifer Macalady got a phone call from a cave diver in the Dominican Republic who told her about a cave there with amazing curtains of slime. Her first thought was, “Who is this crackpot?” but she sent him a sample kit. “The sample he sent back to us was so interesting we knew we had to mount an expedition,” Macalady told Eos Monday. Macalady discussed the findings about these slime curtains in a talk Sunday at the Geologic Society of America’s 2015 meeting in Baltimore. During the expedition 2 years later, Macalady, who is with Pennsylvania State University in University Park, and her colleagues enlisted the aid of divers, whose video of their underground explorations shows rust-colored fronds of slime. These fronds descend from the ceiling and walls of some saltwater-filled chambers of a flooded cave in the country’s southeast called Manantial del Toro. Although the cave contains both fresh water and salt water, the slime is found only in the salt water. To Macalady, who recognized the icky drapery as colonies of microbes living in an ooze of their own secretions, the cave coatings resemble “an inside out teddy bear.” Rusty Clue Whereas the challenge and exotic beauty of Manantial del Toro attracts explorer-divers, the metabolisms of the slime curtains’ microbes lured Macalady. The microbial communities that inhabit these fingers of slime are specialized not only for nitrogen cycling but also iron cycling. The researchers used DNA analyses to identify the microbes that process nitrogen by taking ammonium and transforming it into nitrite. However, that step is only part of the nitrogen cycle. Macalady and her colleagues have yet to identify the microbes involved in the iron cycling, but they know that this process occurs because the slime’s rust color indicates iron oxidation. Could a previously undiscovered microbe capable of both reducing nitrate and oxidizing iron hang from the walls of Manantial del Toro?From what the researchers can tell so far, the slime curtains aren’t taking two of the metabolic steps needed to completely use nitrogen and iron. The first is a pathway that would reduce nitrate and create ammonium, which the microbes then consume again to make nitrite. The second missing piece is a way to oxidize iron (II)—which is soluble and can enter the caves in water—into iron (III), which is insoluble and clings to the slime, giving it a rusty color. Macalady said that organisms can separately perform those processes, but they don’t know of one organism that can do both. Could a previously undiscovered microbe capable of both reducing nitrate and oxidizing iron hang from the walls of Manantial del Toro? Macalady is quick to point out that her team has yet to find an answer to that tantalizing question. Filter Hypothesis A diver swims through Manantial del Toro cave, where clear fresh water fills the upper part of the chamber above cloudy salt water below. The slime curtains live in The nitrogen cycling these slime curtains perform is important to understand, Macalady said, because “nitrogen pollution is famous for messing up coastal ecosystems,” with algal blooms being one consequence. She said that on her team’s next expedition, they aim to measure the flux of water leaving the cave, how much nitrogen escapes into the sea, and if there’s any impact on the surrounding ecosystem. “The ability of microorganisms to remove nitrate as a contaminant, or even ammonia as a contaminant in water, is real,” said Annette Engel, a geomicrobiologist at the University of Tennessee, Knoxville, who is not involved in the work at Manantial del Toro. A Growing Field Because of the dangers of cave exploration, the field of cave microbiology is relatively small. From the 1940s through 2014, researchers have published less than a thousand papers in this field, according to Engel. But with dive and caving technology improving the safety of such excursions, the study of cave microbes is growing. Microbes inhabit cave systems worldwide, both on land and submerged under water. Some come in golds that glitter when water droplets bead on the biofilm’s surfaces, others in azure blues that cling to cave walls. And then there are the rust-colored fronds of Manantial del Toro. “We think slimes will be there, and be conspicuous, wherever there is enough chemical energy to support them. If you feed them, they will come,” said Macalady.
Knowledge Graph
Examples
1 In the last decade, Cave Dwellings have been brought to the attention of scientists and researchers. These traditional dwellings have been regarded as an example of sustainable design.
2 Cave dwellings are common in certain areas of northern China where they serve as homes for more than 40 million people.
3 Cave Dwellings are generally carved out of a hillside or excavated horizontally from a central "sunken courtyard".