The Grand Canyon is a steep-sided canyon carved by the Colorado River in the state of Arizona in the United States. It is contained within and managed by Grand Canyon National Park, the Kaibab National Forest, Grand Canyon-Parashant National Monument, the Hualapai Tribal Nation, the Havasupai people and the Navajo Nation. President Theodore Roosevelt was a major proponent of preservation of the Grand Canyon area, and visited it on numerous occasions to hunt and enjoy the scenery.
The Grand Canyon is 277 miles (446 km) long, up to 18 miles (29 km) wide and attains a depth of over a mile (6,093 feet or 1,857 meters). Nearly two billion years of Earth's geological history have been exposed as the Colorado River and its tributaries cut their channels through layer after layer of rock while the Colorado Plateau was uplifted. While some aspects about the history of incision of the canyon are debated by geologists, several recent studies support the hypothesis that the Colorado River established its course through the area about 5 or 6 million years ago. Since that time, the Colorado River has driven the down-cutting of the tributaries and retreat of the cliffs, simultaneously deepening and widening the canyon.
Grand Canyon tourism
Grand Canyon National Park is one of the world's premier natural attractions, attracting about five million visitors per year. Overall, 83% were from the United States: California (12.2%), Arizona (8.9%), Texas (4.8%), Florida (3.4%) and New York (3.2%) represented the top domestic visitors. Seventeen percent of visitors were from outside the United States; the most prominently represented nations were the United Kingdom (3.8%), Canada (3.5%), Japan (2.1%), Germany (1.9%) and The Netherlands (1.2%).[61] The South Rim is open all year round weather permitting. The North Rim is generally open mid-May to mid-October.
Great Barrier Reef
The Great Barrier Reef is the world's largest coral reef system composed of over 2,900 individual reefs and 900 islands stretching for over 2,300 kilometres (1,400 mi) over an area of approximately 344,400 square kilometres (133,000 sq mi). The reef is located in the Coral Sea, off the coast of Queensland, Australia.
The Great Barrier Reef can be seen from outer space and is the world's biggest single structure made by living organisms. This reef structure is composed of and built by billions of tiny organisms, known as coral polyps. It supports a wide diversity of life and was selected as a World Heritage Site in 1981. CNN labelled it one of the seven natural wonders of the world. The Queensland National Trust named it a state icon of Queensland.
A large part of the reef is protected by the Great Barrier Reef Marine Park, which helps to limit the impact of human use, such as fishing and tourism. Other environmental pressures on the reef and its ecosystem include runoff, climate change accompanied by mass coral bleaching, and cyclic population outbreaks of the crown-of-thorns starfish. According to a study published in October 2012 by the Proceedings of the National Academy of Sciences, the reef has lost more than half its coral cover since 1985.
The Great Barrier Reef has long been known to and used by the Aboriginal Australian and Torres Strait Islander peoples, and is an important part of local groups' cultures and spirituality. The reef is a very popular destination for tourists, especially in the Whitsunday Islands and Cairns regions. Tourism is an important economic activity for the region, generating over $3 billion per year.
Tourism
Due to its vast biodiversity, warm clear waters and accessibility from the tourist boats called "live aboards", the reef is a very popular destination, especially for scuba divers. Tourism on the Great Barrier Reef is concentrated in Cairns and also The Whitsundays due to their accessibility. These areas make up 7%–8% of the Park's area. The Whitsundays and Cairns have their own Plans of Management. Many cities along the Queensland coast offer daily boat trips. Several continental and coral cay islands are now resorts, including Green Island and Lady Elliot Island. As of 1996, 27 islands on the Great Barrier Reef supported resorts.
In 1996, most of the tourism in the region was domestically generated and the most popular visiting times were during the Australian winter. At this time, it was estimated that tourists to the Great Barrier Reef contributed A$776 million per annum. As the largest commercial activity in the region, it was estimated in 2003 that tourism generated over A$4 billion annually, and the 2005 estimate increased to A$5.1 billion. A Deloitte report published by the Great Barrier Reef Marine Park Authority in March 2013 states that the Reef's 2,000 kilometres of coastline attracts tourism worth A$6.4 billion annually and employs more than 64,000 people.
Approximately two million people visit the Great Barrier Reef each year. Although most of these visits are managed in partnership with the marine tourism industry, there is a concern among the general public that tourism is harmful to the Great Barrier Reef.
A variety of boat tours and cruises are offered, from single day trips, to longer voyages. Boat sizes range from dinghies to superyachts. Glass-bottomed boats and underwater observatories are also popular, as are helicopter flights. By far, the most popular tourist activities on the Great Barrier Reef are snorkelling and diving, for which pontoons are often used, and the area is often enclosed by nets. The outer part of the Great Barrier Reef is favoured for such activities, due to water quality.
Fishing
The fishing industry in the Great Barrier Reef, controlled by the Queensland Government, is worth A$1 billion annually. It employs approximately 2000 people, and fishing in the Great Barrier Reef is pursued commercially, for recreation, and as a traditional means for feeding one's family.
Guanabara Bay
The name Guanabara comes from the Tupi language, goanã-pará, from gwa "bay", plus nã "similar to" and ba'ra "sea". Traditionally, it is also translated as "the bosom of sea."
Guanabara Bay was first encountered by Europeans on January 1, 1502, when one of the Portuguese explorers Gaspar de Lemos and Gonçalo Coelho arrived on its shores. According to some historians, the name given by the exploration team to the bay was originally Ria de Janeiro "January Sound", then a confusion took place between the word ria, which at the time was used to designate a bay or a sound, and rio "river". As a result, the name of the bay was soon fixed as Rio de Janeiro. Later, the city was named after the bay. Natives of the Tamoio and Tupiniquim tribes inhabited the shores of the bay.
The bay is crossed by the Rio-Niterói Bridge (13.29 kilometres (8.26 mi) long and with a central span 72 metres (236 ft) high) and there is heavy boat and ship traffic, including regular ferryboat lines. The Port of Rio de Janeiro, as well as the city's two airports, Galeão - Antônio Carlos Jobim International Airport (on Governador Island) and Santos Dumont Airport (on reclaimed land next to downtown Rio), are located on its shores. The Federal University of Rio de Janeiro main campus is located on the artificial Fundão Island. A maze of smaller bridges interconnect the two largest islands, Fundão and Governador, to the mainland.
One of the world's largest landfills is located at Jardim Gramacho adjacent to Guanabara Bay. It was closed in 2012 after 34 years of operation. The landfill attracted attention from environmentalists and it supported 1700 people scavenging for recyclable materials.
There are more than 130 islands dotting the bay, including:
- Lajes
- Ilha do Governador – site of Rio de Janeiro's Galeão - Antônio Carlos Jobim International Airport
- Ilha de Paquetá
- Ilha das Cobras
- Flores
- Ilha Fiscal
- Ilha da Boa Viagem
- Villegaignon
- Fundão
Mount Everest
Mount Everest, also known in Nepal as Sagarmāthā and in Tibet as Chomolungma, is Earth's highest mountain. It is located in the Mahalangur mountain range in Nepal and Tibet. Its peak is 8,848 metres (29,029 ft) above sea level. The international border between China (Tibet Autonomous Region) and Nepal runs across Everest's precise summit point. Its massif includes neighbouring peaks Lhotse, 8,516 m (27,940 ft); Nuptse, 7,855 m (25,771 ft) and Changtse, 7,580 m (24,870 ft).
In 1856, the Great Trigonometrical Survey of India established the first published height of Everest, then known as Peak XV, at 8,840 m (29,002 ft). The current official height of 8,848 m (29,029 ft) as recognised by China and Nepal was established by a 1955 Indian survey and subsequently confirmed by a Chinese survey in 1975. In 1865, Everest was given its official English name by the Royal Geographical Society upon a recommendation by Andrew Waugh, the British Surveyor General of India. As there appeared to be several different local names, Waugh chose to name the mountain after his predecessor in the post, Sir George Everest, despite George Everest's objections.
Mount Everest attracts many climbers, some of them highly experienced mountaineers. There are two main climbing routes, one approaching the summit from the southeast in Nepal (known as the standard route) and the other from the north in Tibet. While not posing substantial technical climbing challenges on the standard route, Everest presents dangers such as altitude sickness, weather, wind as well as significant objective hazards from avalanches and the Khumbu Icefall. As of 2016, there are well over 200 corpses still on the mountain, with some of them even serving as landmarks.
First successful ascent by Tenzing and Hillary
In 1953, a ninth British expedition, led by John Hunt, returned to Nepal. Hunt selected two climbing pairs to attempt to reach the summit. The first pair (Tom Bourdillon and Charles Evans) came within 100 m (330 ft) of the summit on 26 May 1953, but turned back after running into oxygen problems. As planned, their work in route finding and breaking trail and their caches of extra oxygen were of great aid to the following pair. Two days later, the expedition made its second and final assault on the summit with its second climbing pair, the New Zealander Edmund Hillary and Tenzing Norgay, a Nepali sherpa climber from Darjeeling, India. They reached the summit at 11:30 am local time on 29 May 1953 via the South Col Route. At the time, both acknowledged it as a team effort by the whole expedition, but Tenzing revealed a few years later that Hillary had put his foot on the summit first. They paused at the summit to take photographs and buried a few sweets and a small cross in the snow before descending.
News of the expedition's success reached London on the morning of Queen Elizabeth II's coronation, 2 June. Returning to Kathmandu a few days later, Hunt (a Briton) and Hillary (a New Zealander) discovered that they had been promptly knighted in the Order of the British Empire for the ascent. Tenzing, a Nepali sherpa who was a citizen of India, was granted the George Medal by the UK. Hunt was ultimately made a life peer in Britain, while Hillary became a founding member of the Order of New Zealand. Hillary and Tenzing are also nationally recognised in Nepal, where annual ceremonies in schools and offices celebrate their accomplishment.
The next successful ascent was on 23 May 1956 by Ernst Schmied and Juerg Marmet. This was followed by Dölf Reist and Hans-Rudolf von Gunten on 24 May 1957. Wang Fuzhou, Gonpo and Qu Yinhua of China made the first reported ascent of the peak from the North Ridge on 25 May 1960. The first American to climb Everest, Jim Whittaker, joined by Nawang Gombu, reached the summit on 1 May 1963.
Climbing
Permits
There were 334 climbing permits issued in 2014, these were extended for free because of the tragedy that struck. In 2015 there was 357 permits to climb Everest, but the mountain was closed again because of the avalanche and earthquake. Nepal then extended the unused 2014/15 permits until 2019 (Nepali permits cost about 10,000 USD for foreigners). So people who bought a permit in 2014 or 2015 can still use it for an expedition to Everest until 2019 (normally they are only valid for one year). This was an example of hospitality that Nepali's have become famous for; an extension was especially requested by expedition firms (which in turn bring resources into the country due for mountaineering). Nepal is essentially a "fourth world" country, one of the poorest non-African countries and the 19th poorest country in the world. Despite this, Nepal has been very welcoming to tourists and a significant tourism industry has been established.
Routes
Mt. Everest has two main climbing routes, the southeast ridge from Nepal and the north ridge from Tibet, as well as many other less frequently climbed routes. Of the two main routes, the southeast ridge is technically easier and is the more frequently used route. It was the route used by Edmund Hillary and Tenzing Norgay in 1953 and the first recognised of fifteen routes to the top by 1996. This was, however, a route decision dictated more by politics than by design as the Chinese border was closed to the western world in the 1950s after the People's Republic of China invaded Tibet.
Most attempts are made during May before the summer monsoon season. As the monsoon season approaches, a change in the jet stream at this time pushes it northward, thereby reducing the average wind speeds high on the mountain. While attempts are sometimes made after the monsoons in September and October, when the jet stream is again temporarily pushed northward, the additional snow deposited by the monsoons and the less stable weather patterns (tail end of the monsoon) makes climbing extremely difficult.
Summit
The routes usually share one spot in common, the summit itself. The summit of Everest has been described as "the size of a dining room table". The summit is capped with snow over ice over rock, and the layer of snow varies from year to year. The rock summit is made of Ordovician limestone and is a low-grade metamorphic rock according to Montana State University. (see survey section for more on its height and about the Everest rock summit)
Below the summit there is an area known as "rainbow valley", filled with dead bodies still wearing brightly coloured winter gear. Down to about 8000 meters is an area commonly called the "death zone", due to the high danger and low oxygen because of the low pressure. The summit penetrates the stratosphere, the next major layer in the atmosphere above the troposphere.
Death zone
At the higher regions of Mount Everest, climbers seeking the summit typically spend substantial time within the death zone (altitudes higher than 8,000 metres (26,000 ft)), and face significant challenges to survival. Temperatures can dip to very low levels, resulting in frostbite of any body part exposed to the air. Since temperatures are so low, snow is well-frozen in certain areas and death or injury by slipping and falling can occur. High winds at these altitudes on Everest are also a potential threat to climbers.
Another significant threat to climbers is low atmospheric pressure. The atmospheric pressure at the top of Everest is about a third of sea level pressure or 0.333 standard atmospheres (337 mbar), resulting in the availability of only about a third as much oxygen to breathe.
Debilitating effects of the death zone are so great that it takes most climbers up to 12 hours to walk the distance of 1.72 kilometres (1.07 mi) from South Col to the summit. Achieving even this level of performance requires prolonged altitude acclimatization, which takes 40–60 days for a typical expedition. A sea-level dweller exposed to the atmospheric conditions at the altitude above 8,500 m (27,900 ft) without acclimatization would likely lose consciousness within 2 to 3 minutes.
Aurora
An aurora, sometimes referred to as a polar light, is a natural light display in the sky, predominantly seen in the high latitude (Arctic and Antarctic) regions. Auroras are produced when the magnetosphere is sufficiently disturbed by the solar wind that the trajectories of charged particles in both solar wind and magnetospheric plasma, mainly in the form of electrons and protons, precipitate them into the upper atmosphere (thermosphere/exosphere), where their energy is lost. The resulting ionization and excitation of atmospheric constituents emits light of varying colour and complexity. The form of the aurora, occurring within bands around both polar regions, is also dependent on the amount of acceleration imparted to the precipitating particles. Precipitating protons generally produce optical emissions as incident hydrogen atoms after gaining electrons from the atmosphere. Proton auroras are usually observed at lower latitudes. Different aspects of an aurora are elaborated in various sections below.
Auroras are occasionally seen in latitudes below the auroral zone, when a geomagnetic storm temporarily enlarges the auroral oval. Large geomagnetic storms are most common during the peak of the eleven-year sunspot cycle or during the three years after the peak. An aurora may appear overhead as a "corona" of rays, radiating from a distant and apparent central location, which results from perspective. An electron spirals (gyrates) about a field line at an angle that is determined by its velocity vectors, parallel and perpendicular, respectively, to the local geomagnetic field vector B. This angle is known as the “pitch angle” of the particle. The distance, or radius, of the electron from the field line at any time is known as its Larmor radius. The pitch angle increases as the electron travels to a region of greater field strength nearer to the atmosphere. Thus it is possible for some particles to return, or mirror, if the angle becomes 90 degrees before entering the atmosphere to collide with the denser molecules there. Other particles that do not mirror enter the atmosphere and contribute to the auroral display over a range of altitudes. Other types of auroras have been observed from space, e.g."poleward arcs" stretching sunward across the polar cap, the related "theta aurora", and "dayside arcs" near noon. These are relatively infrequent and poorly understood. There are other interesting effects such as flickering aurora, "black aurora" and sub-visual red arcs. In addition to all these, a weak glow (often deep red) observed around the two polar cusps, the field lines separating the ones that close through the Earth from those that are swept into the tail and close remotely.
Historical theories, superstition and mythology
Magnetic control of the aurora was mentioned by Ancient Greek explorer/geographer Pytheas, Hiorter, and Celsius described in 1741 evidence that large magnetic fluctuations occurred whenever the aurora was observed overhead. It was also later realized that large electric currents were associated with the aurora, flowing in the region where auroral light originated. Multiple superstitions and obsolete theories explaining the aurora have emerged over the centuries.
- Seneca speaks diffusely on auroras in the first book of his Naturales Quaestiones, drawing mainly from Aristotle; he classifies them "putei" or wells when they are circular and "rim a large hole in the sky", "pithaei" when they look like casks, "chasmata" from the same root of the English chasm, "pogoniae" when they are bearded, "cyparissae" when they look like cypresses), describes their manifold colors and asks himself whether they are above or below the clouds. He recalls that under Tiberius, an aurora formed above Ostia, so intense and so red that a cohort of the army, stationed nearby for fireman duty, galloped to the city.
- Walter William Bryant wrote in his book Kepler (1920) that Tycho Brahe "seems to have been something of a homœopathist, for he recommends sulfur to cure infectious diseases “brought on by the sulphurous vapours of the Aurora Borealis."
- Benjamin Franklin theorized that the "mystery of the Northern Lights" was caused by a concentration of electrical charges in the polar regions intensified by the snow and other moisture.
The northern lights have had a number of names throughout history. The Cree called the phenomenon the "Dance of the Spirits". In Medieval Europe, the auroras were commonly believed to be a sign from God.
Paricutin volcano
The Parícutin Volcano is located in the Mexican municipality of Nuevo Parangaricutiro, Michoacán, 29km west of the city of Uruapan and about 322 km west of Mexico City. It lies on the northern flank of the Cerros de Tancítaro, on an old shield volcano and extends 3,170 meters above sea level and 424 meters above the Valley of Quitzocho-Cuiyusuru, wedged against old volcanic mountain chains and surrounded by small volcanic cones with the intervening valleys occupied by small fields and orchards or small settlements from groups of a few houses to those the size of towns.
The volcano lies on, and is a product of, the Trans-Mexican Volcanic Belt, which runs 900km west to east across central Mexico. It includes the Sierra Nevada mountain range, (a set of extinct volcanoes) as well as thousands of cinder cones and volcanic events. Volcanic activity here has created the Central Mexican Plateau, and rock deposits up to 1.8km deep. It has also created fertile soils and some of Mexico’s most productive farmland. The volcanic activity here is a result of the subduction of the Rivera and Cocos plates along the Middle America Trench. More specifically, the volcano is the youngest of the approximately 1,400 volcanic vents of the Michoacán-Guanajuato volcanic field, a 40,000km2 basalt plateau, filled with scoria cones, like Parícutin, along with small shield volcanoes, maars, tuff rings and lava domes. Scoria cones are the most common type of volcano in Mexico, appearing suddenly, and building a cone-shaped mountain with steep slopes before going extinct, with Parícutin's immediate predecessor being Jorullo, also in Michoacán, which arose in 1759.
Currently the crater of the volcano is about 200 meters across and it is possible to both climb the volcano and walk around the entire perimeter. Although classified as extinct by scientists, it is still hot, and seeping rainwater reacts with this heat so that the cone still emits steam in various streams. However, the forces that created the volcano are still active. In 1997 there was a vigorous swarm of 230 earthquakes with five above 3.9 in the Paricutin area due to tectonic movement. There were some reports of rumbling in 1995 and of black steam and rumbling in 1998. In the summer of 2006, there was another major volcanic earthquake swarm, with over 300 located near the volcano, indicating magma movement, but with no eruption at Paricutin or anywhere else.
Victoria Falls
Victoria Falls, or Mosi-oa-Tunya (Tokaleya Tonga: the Smoke that Thunders), is a waterfall in southern Africa on the Zambezi River at the border of Zambia and Zimbabwe.
David Livingstone, the Scottish missionary and explorer, is believed to have been the first European to view Victoria Falls on 16 November 1855 from what is now known as Livingstone Island, one of two land masses in the middle of the river, immediately upstream from the falls on the Zambian side. Livingstone named his discovery in honour of Queen Victoria of Britain, but the indigenous name, Mosi-oa-Tunya—"the smoke that thunders"—continues in common usage as well. The nearby national park in Zambia is named Mosi-oa-Tunya, whereas the national park and town on the Zimbabwean shore are both named Victoria Falls. The World Heritage List officially recognizes both names.
While it is neither the highest nor the widest waterfall in the world, it is classified as the largest, based on its combined width of 1,708 metres (5,604 ft) and height of 108 metres (354 ft), resulting in the world's largest sheet of falling water. Victoria Falls is roughly twice the height of North America's Niagara Falls and well over twice the width of its Horseshoe Falls. In height and width Victoria Falls is rivalled only by Argentina and Brazil's Iguazu Falls.
There are two islands on the crest of the falls that are large enough to divide the curtain of water even at full flood: Boaruka Island (or Cataract Island) near the western bank, and Livingstone Island near the middle—the point from which Livingstone first viewed the falls. At less than full flood, additional islets divide the curtain of water into separate parallel streams. The main streams are named, in order from Zimbabwe (west) to Zambia (east): Devil's Cataract (called Leaping Water by some), Main Falls, Rainbow Falls (the highest) and the Eastern Cataract.
The Zambezi river, upstream from the falls, experiences a rainy season from late November to early April, and a dry season the rest of the year. The river's annual flood season is February to May with a peak in April, The spray from the falls typically rises to a height of over 400 metres (1,300 ft), and sometimes even twice as high, and is visible from up to 48 km (30 mi) away. At full moon, a "moonbow" can be seen in the spray instead of the usual daylight rainbow. During the flood season, however, it is impossible to see the foot of the falls and most of its face, and the walks along the cliff opposite it are in a constant shower and shrouded in mist. Close to the edge of the cliff, spray shoots upward like inverted rain, especially at Zambia's Knife-Edge Bridge.
As the dry season takes effect, the islets on the crest become wider and more numerous, and in September to January up to half of the rocky face of the falls may become dry and the bottom of the First Gorge can be seen along most of its length. At this time it becomes possible (though not necessarily safe) to walk across some stretches of the river at the crest. It is also possible to walk to the bottom of the First Gorge at the Zimbabwean side. The minimum flow, which occurs in November, is around a tenth of the April figure; this variation in flow is greater than that of other major falls, and causes Victoria Falls' annual average flow rate to be lower than might be expected based on the maximum flow.
See also
- Seven Wonders of Canada
- Seven Wonders of Colombia
- Seven Wonders of India
- Seven Wonders of Poland
- Seven Wonders of Portugal
- Seven Natural Wonders of Romania
- Seven Wonders of Russia
- Seven Wonders of Serbia
- Seven Wonders of Ukraine
- Seven Wonders of Wales
- 12 Treasures of Spain
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