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85-644: The Grand Canyon is a steep-sided canyon carved by the Colorado River in Arizona , United States. 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). The canyon and adjacent rim are contained within Grand Canyon National Park , the Kaibab National Forest , Grand Canyon–Parashant National Monument ,

170-524: A sipapu . In September 1540, under orders from the conquistador Francisco Vázquez de Coronado to search for the fabled Seven Cities of Cibola , Captain García López de Cárdenas , along with Hopi guides and a small group of Spanish soldiers, traveled to the south rim of the Grand Canyon between Desert View and Moran Point. Pablo de Melgrossa, Juan Galeras, and a third soldier descended some one third of

255-439: A Notice of Intent to suspend approvals for new uranium mining in the area. In 2012, Salazar established a 20-year moratorium (known as the "Northern Arizona Withdrawal") withdrawing 1 million acres (4,000 km) from the permitting process for uranium and hardrock mining, stating "People from all over the country and around the world come to visit the Grand Canyon. Numerous American Indian tribes regard this magnificent icon as

340-436: A band of Native Americans to Christianity. He described the canyon as "profound". James Ohio Pattie, along with a group of American trappers and mountain men, may have been the next European to reach the canyon, in 1826. Jacob Hamblin , a Mormon missionary, was sent by Brigham Young in the 1850s to locate suitable river crossing sites in the canyon. Building good relations with local Hualapai and white settlers, he reached

425-686: A dense barrier. Groundwater from the C-acquifer can flow laterally, appearing as seeps along the canyon walls at the base of the Coconino Sandstone but can also descend vertically through fault zones to recharge the underlying confined R-aquifer. The R-aquifer, also known as the Red Wall Muav aquifer, is a karst aquifer. It involves an area of substantial fracturing through the Redwall Limestone, Temple Butte Formation and Cambrian Muav Limestone of

510-533: A group of Spanish soldiers, explored southern Utah and traveled along the north rim of the canyon in Glen and Marble Canyons in search of a route from Santa Fe to California in 1776. They eventually found a crossing, formerly known as the "Crossing of the Fathers", that today lies under Lake Powell . Also in 1776, Fray Francisco Garces, a Franciscan missionary, spent a week near Havasupai unsuccessfully attempting to convert

595-812: A reduced fee. However, research articles published after 1997 are available for free (with online registration) one year after they are published i.e. delayed open access . Significant public-health related articles are also available for free, sometimes immediately after publication. AAAS members may also access the pre-1997 Science archives at the Science website, where it is called "Science Classic". Institutions can opt to add Science Classic to their subscriptions for an additional fee. Some older articles can also be accessed via JSTOR and ProQuest . The journal also participates in initiatives that provide free or low-cost access to readers in developing countries, including HINARI , OARE, AGORA , and Scidev.net . Other features of

680-551: A result the team eventually had to subsist on starvation rations. Passing through (or portaging around) a series of dangerous rapids, the group passed down the Green River , reaching its confluence with the Colorado River, near present-day Moab, Utah , on July 17. Continuing on down the Colorado River, the party encountered more rapids and falls. On August 28, 1869, faced with what some felt to be impassable rapids, three men left

765-813: A rift between two mountain peaks, such as those in ranges including the Rocky Mountains , the Alps , the Himalayas or the Andes . Usually, a river or stream carves out such splits between mountains. Examples of mountain-type canyons are Provo Canyon in Utah or Yosemite Valley in California's Sierra Nevada . Canyons within mountains, or gorges that have an opening on only one side, are called box canyons. Slot canyons are very narrow canyons that often have smooth walls. Steep-sided valleys in

850-501: A sacred place and millions of people in the Colorado River Basin depend on the river for drinking water, irrigation, industrial and environmental use." However, Salazar's 20-year moratorium on new mines still allows mines with previous authorization to operate. Multiple challenges have been brought into court both against the moratorium and against the operation of uranium mines in the area. The federal government's 2012 moratorium

935-697: A similar source to the Havasu Spring upwelling from the Redwall-Muav aquifer. Sites with younger estimated mean ages tend to be associated with the unconfined Coconino aquifer. They may recharge quickly as a result of snowmelt, run-off and local precipitation. It is likely that the deeper confined R-aquifer relies primarily on snowmelt from the San Francisco Peaks to recharge. Other research has tried to relate groundwater flow paths to possible levels of risk for contamination and identify vulnerability regions for

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1020-509: A substantial departure from prior widely supported scientific consensus. In a 2008 study, Victor Polyak examined caves near the Grand Canyon and placed their origins about 17   million years ago. The study, which was published in the journal Science in 2008, used uranium-lead dating to analyze calcite deposits found on the walls of nine caves throughout the canyon. In another 2008 study, Rebecca Flowers reported on apatite (U-Th)/He thermochronometry results suggesting that parts of

1105-570: A time the only record concerning this rather mythical locality, was rather magnified than detracted from by the accounts of one or two trappers, who professed to have seen the cañon". According to the San Francisco Herald , in a series of articles run in 1853, Captain Joseph R. Walker in January 1851 with his nephew James T. Walker and six men, traveled up the Colorado River to a point where it joined

1190-670: A wide area stretching from the San Francisco Peaks eastwards towards the Four Corners. Archaeological and linguistic evidence suggests the Navajo descended from the Athabaskan people near Great Slave Lake , Canada, who migrated after the 11th   century. In the mythology of some Third Mesa Hopi communities, the Grand Canyon was the location humankind arose out of the Third World from

1275-514: Is actually 1 km wider than the Grand Canyon, making it the widest canyon in the world. Some canyons have notable cultural significance. Evidence of archaic humans has been discovered in Africa's Olduvai Gorge . In the southwestern United States, canyons are important archeologically because of the many cliff-dwellings built in such areas, largely by the ancient Pueblo people who were their first inhabitants. The following list contains only

1360-559: Is called a confined aquifer, while water below the surface and above an aquitard is called an unconfined aquifer. The different geologic levels of the Grand Canyon have created two major aquifers where groundwater collects. The higher C-aquifer is an unconfined aquifer. It collects groundwater that seeps through the Kaibab and Toroweap Formations into the Coconino Sandstone. Below it, the Permian Hermit Formation and Supai Group provide

1445-487: Is known for its visually overwhelming size and its intricate and colorful landscape. Geologically, it is significant because of the thick sequence of ancient rocks that are well preserved and exposed in the walls of the canyon. These rock layers record much of the early geologic history of the North American continent. Uplift associated with mountain formation later moved these sediments thousands of feet upward and created

1530-644: Is occasionally used in the United Kingdom . In South Africa, kloof (in Krantzkloof Nature Reserve ) is used along with canyon (as in Blyde River Canyon ) and gorge (in Oribi Gorge ). Most canyons were formed by a process of long-time erosion from a plateau or table-land level. The cliffs form because harder rock strata that are resistant to erosion and weathering remain exposed on

1615-447: Is publishing important original scientific research and research reviews, but Science also publishes science-related news, opinions on science policy and other matters of interest to scientists and others who are concerned with the wide implications of science and technology. Unlike most scientific journals , which focus on a specific field, Science and its rival Nature cover the full range of scientific disciplines . According to

1700-580: Is similarly imprecise, especially if one includes mountain canyons, as well as canyons cut through relatively flat plateaus (which have a somewhat well-defined rim elevation). The Yarlung Tsangpo Grand Canyon (or Tsangpo Canyon), along the Yarlung Tsangpo River in Tibet , is regarded by some as the deepest canyon on Earth at 5,500 metres (18,000 ft). It is slightly longer than the Grand Canyon in

1785-582: Is soluble to a certain extent, cave systems form in the rock. When a cave system collapses, a canyon is left, as in the Mendip Hills in Somerset and Yorkshire Dales in Yorkshire , England. A box canyon is a small canyon that is generally shorter and narrower than a river canyon, with steep walls on three sides, allowing access and egress only through the mouth of the canyon. Box canyons were frequently used in

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1870-619: Is the Fish River Canyon in Namibia . In August 2013, the discovery of Greenland 's Grand Canyon was reported, based on the analysis of data from Operation IceBridge . It is located under an ice sheet. At 750 kilometres (470 mi) long, it is believed to be the longest canyon in the world. Despite not being quite as deep or long as the Grand Canyon, the Capertee Valley in Australia

1955-465: The Journal Citation Reports , Science ' s 2023 impact factor was 44.7. Studies of methodological quality and reliability have found that some high-prestige journals including Science "publish significantly substandard structures", and overall "reliability of published research works in several fields may be decreasing with increasing journal rank". Although it is the journal of

2040-606: The Boone and Crockett Club helped form the National Parks Association , which in turn lobbied for the Antiquities Act of 1906 which gave Roosevelt the power to create national monuments. Once the act was passed, Roosevelt immediately added adjacent national forest lands and redesignated the preserve a U.S. National Monument on January 11, 1908. Opponents such as land and mining claim holders blocked efforts to reclassify

2125-463: The Crossing of the Fathers , crossed the location that would become Lees Ferry on a raft in 1858 and Pearce Ferry (later operated by, and named for, Harrison Pearce ). He also acted as an advisor to John Wesley Powell , before his second expedition to the Grand Canyon, serving as a diplomat between Powell and the local native tribes to ensure the safety of his party. In 1857, Edward Fitzgerald Beale

2210-676: The EPA ' s Maximum Contaminant Level for drinking water, 30 μg/L. At 86% of sites, uranium concentrations were below the Canadian level for protection of freshwater aquatic life, 15 μg/L. On August 8, 2023, it was announced that U.S. President Joe Biden will designate Baaj Nwaavjo I’tah Kukveni – Ancestral Footprints of the Grand Canyon National Monument, a move aimed at conserving nearly 1 million acres of greater Grand Canyon landscape. Canyon A canyon may also refer to

2295-722: The Hualapai Indian Reservation , the Havasupai Indian Reservation and the Navajo Nation . The surrounding area is contained within the Baaj Nwaavjo I'tah Kukveni – Ancestral Footprints of the Grand Canyon National Monument . President Theodore Roosevelt was a major proponent of the preservation of the Grand Canyon area and visited it on numerous occasions to hunt and enjoy the scenery. Nearly two billion years of Earth's geological history have been exposed as

2380-591: The Pecos Classification , suggests their emergence was around 1200  BCE during the Basketmaker II Era . Beginning with the earliest explorations and excavations, researchers have believed that the Ancestral Puebloans are ancestors of the modern Pueblo peoples . In addition to the Ancestral Puebloans, a number of distinct cultures have inhabited the Grand Canyon area. The Cohonina lived to

2465-454: The United States , place names generally use canyon in the southwest (due to their proximity to Spanish-speaking Mexico ) and gorge in the northeast (which is closer to French Canada ), with the rest of the country graduating between these two according to geography. In Canada , a gorge is usually narrow while a ravine is more open and often wooded. The military-derived word defile

2550-481: The elevation summary of the Colorado River for present conditions). Weather conditions during the ice ages also increased the amount of water in the Colorado River drainage system. The ancestral Colorado River responded by cutting its channel faster and deeper. The base level and course of the Colorado River (or its ancestral equivalent) changed 5.3   million years ago when the Gulf of California opened and lowered

2635-561: The formations were deposited in warm shallow seas, near-shore environments (such as beaches), and swamps as the seashore repeatedly advanced and retreated over the edge of a proto-North America. Major exceptions include the Permian Coconino Sandstone , which contains abundant geological evidence of aeolian sand dune deposition. Several parts of the Supai Group also were deposited in non-marine environments. The great depth of

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2720-631: The seabed of the continental slope are referred to as submarine canyons . Unlike canyons on land, submarine canyons are thought to be formed by turbidity currents and landslides . The word canyon is Spanish in origin ( cañón , pronounced [kaˈɲon] ), with the same meaning. The word canyon is generally used in North America , while the words gorge and ravine (French in origin) are used in Europe and Oceania , though gorge and ravine are also used in some parts of North America. In

2805-455: The western United States as convenient corrals, with their entrances fenced. The definition of "largest canyon" is imprecise, because a canyon can be large by its depth, its length, or the total area of the canyon system. Also, the inaccessibility of the major canyons in the Himalaya contributes to their not being regarded as candidates for the biggest canyon. The definition of "deepest canyon"

2890-563: The AAAS and executive publisher of Science , stated that the journal was becoming increasingly international: "[I]nternationally co-authored papers are now the norm—they represent almost 60 percent of the papers. In 1992, it was slightly less than 20 percent." The latest editions of the journal are available online, through the main journal website, only to subscribers, AAAS members, and for delivery to IP addresses at institutions that subscribe; students, K–12 teachers, and some others can subscribe at

2975-595: The AAAS, membership in the AAAS is not required to publish in Science . Papers are accepted from authors around the world. Competition to publish in Science is very intense, as an article published in such a highly cited journal can lead to attention and career advancement for the authors. Fewer than 7% of articles submitted are accepted for publication. Science was founded by New York journalist John Michels in 1880 with financial support from Thomas Edison and later from Alexander Graham Bell . (Edison received favorable editorial treatment in return, without disclosure of

3060-601: The C-aquifer. Much of the water that could potentially recharge the aquifers is likely released as springs rather than reaching the aquifers. Studies of the chemical composition of groundwater at sites across the Grand Canyon region indicate that groundwater contains a fraction of modern water (post-1950), and that many springs have a mix of modern water and older groundwater. Estimated mean ages for South Rim groundwater range from 6 years old (San Francisco Peaks) to nearly 20,000 years old (Bar Four well, Blue Spring). Groundwater age in

3145-620: The Colorado Plateau. The higher elevation has also resulted in greater precipitation in the Colorado River drainage area, but not enough to change the Grand Canyon area from being semi-arid. The uplift of the Colorado Plateau is uneven, and the Kaibab Plateau that the Grand Canyon bisects is over one thousand feet (300 m) higher at the North Rim than at the South Rim. Almost all runoff from

3230-475: 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 to 6 million years ago. Since that time, the Colorado River has driven

3315-475: The Colorado River and the Grand Canyon in the first expedition down the canyon. Powell ordered a shipwright to build four reinforced Whitewall rowboats from Chicago and had them shipped west on the newly completed Continental railroad. He hired nine men, including his brother Walter, and collected provisions for ten months. They set out from Green River, Wyoming , on May 24. On June 7, they lost one of their boats, 1/3 of their food, and other badly-needed supplies: as

3400-630: The Colorado all of the way to the Gulf of California . The Grand Canyon became an official national monument in 1908 and a national park in 1919. U.S. President Theodore Roosevelt visited the Grand Canyon in 1903. An avid outdoorsman and staunch conservationist, Roosevelt established the Grand Canyon Game Preserve on November 28, 1906. Livestock grazing was reduced, but predators such as mountain lions, eagles, and wolves were eradicated. Roosevelt along with other members of his conservation group,

3485-570: The Department of Interior started experimenting with “adaptive management” of the Glen Canyon Dam, using a High-Flow Experiment (HFE) water release to shift volumes of sand and monitoring effects such as the dispersal of invasive tamarisk seeds. However, as of 2022, extreme drought has caused water levels in Lake Powell to drop so much that a planned release of water has been delayed, to ensure that

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3570-509: The Forest Service had not acted arbitrarily in making its decision. A study examining samples of groundwater from 180 spring sites and 26 wells in the Grand Canyon region has assessed the presence of uranium in groundwater from September 1, 1981, to October 7, 2020. The goal of the study was to establish a baseline assessment of groundwater conditions in the Grand Canyon region. At 95% of sites, maximum observed uranium concentrations were below

3655-420: The Glen Canyon Dam can continue to generate hydropower . Between 2003 and 2011, 2,215 mining claims had been requested that are adjacent to the canyon, including claims for uranium mines. Critics of uranium mining are concerned that uranium will leach into the aquifers feeding the Colorado River and contaminate the water supply for up to 18 million people. In 2009, U.S. Interior Secretary Ken Salazar published

3740-604: The Grand Canyon Trust sought to block the reopening of the Pinyon Plain Mine (formerly Canyon Uranium Mine). Activity at the mine had ceased in 1992, ten years prior to the moratorium on new development in 2012. Appellants challenged the U.S. Forest Service's consultation process for approving reopening of the mine. As of February 22, 2022, the 9th U.S. Circuit Court of Appeals rejected the arguments in No. 20-16401, concluding that

3825-495: The Grand Canyon and especially the height of its strata (most of which formed below sea level) can be attributed to 5,000–10,000 feet (1,500–3,000 m) of uplift of the Colorado Plateau, starting about 65   million years ago (during the Laramide orogeny ). This uplift has steepened the stream gradient of the Colorado River and its tributaries, which in turn has increased their speed and thus their ability to cut through rock (see

3910-574: The Grand Canyon and tributary canyons. Springs discharge to the Grand Canyon in areas of lower Paleozoic carbonates, and are associated with geologic faults and fractures. Fractures are believed to provide dominant pathways both for vertical circulation in the Paleozoic section, and for lateral collection and transport of water to springs deep in the canyons. The largest springs discharge from the R-aquifer. A smaller number of springs discharge at lower rates from

3995-419: The Grand Canyon had reached a depth near to the modern depth around 20   million years ago. In a subsequent study published in the journal Science in 2012, she suggested that the western part of the Grand Canyon could be as old as 70   million years. The emerging scientific consensus is that the canyon is made up of multiple segments which formed at different times and eventually connected to become

4080-400: The North Rim (which also gets more rain and snow) flows toward the Grand Canyon, while much of the runoff on the plateau behind the South Rim flows away from the canyon (following the general tilt). The result is deeper and longer tributary washes and canyons on the north side and shorter and steeper side canyons on the south side. Temperatures on the North Rim are generally lower than those on

4165-549: The South Rim because of the greater elevation (averaging 8,000 feet or 2,400 meters above sea level). Heavy rains are common on both rims during the summer months. Access to the North Rim via the primary route leading to the canyon ( State Route 67 ) is limited during the winter season due to road closures. The Grand Canyon is part of the Colorado River basin, which has developed over the past 70   million years. For more than 150 years, scientists have gathered data, proposed new ideas, and debated sometimes contentious theories about

4250-560: The South Rim groundwater system also correlates to longitude, with age increasing from east to west from Red Canyon to Boucher springs. Surprisingly, the Canyon Mine Observation well is more similar to Redwall-Muav aquifer wells (R-aquifer) than to the Coconino C-aquifer. This suggests the possibility of a hydrologic connection or similar recharge sources for that hydrologic position. Old groundwater from Havasupai well may have

4335-520: The Tonto Group. Five individual systems flow through the R-aquifer and compose the regional groundwater-flow system which drains into the Grand Canyon: Kaibab, Uinkaret-Kanab, Marble-Shinumo, Cataract, and Blue Spring. The flow of groundwater in the Grand Canyon region is influenced in multiple ways by geologic faults and folds . Discharge from the R-aquifer appears as springs and seeps in both

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4420-582: The United States, with an average depth of 1,600 metres (5,200 ft) and a volume of 4.17 trillion cubic metres (147 trillion cubic feet), is one of the world's largest canyons. It was among the 28 finalists of the New 7 Wonders of Nature worldwide poll. (Some referred to it as one of the seven natural wonders of the world .) The largest canyon in Europe is Tara River Canyon . The largest canyon in Africa

4505-606: The United States. Others consider the Kali Gandaki Gorge in midwest Nepal to be the deepest canyon, with a 6,400-metre (21,000 ft) difference between the level of the river and the peaks surrounding it. Vying for the deepest canyon in the Americas is the Cotahuasi Canyon and Colca Canyon , in southern Peru. Both have been measured at over 3,500 metres (11,500 ft) deep. The Grand Canyon of northern Arizona in

4590-427: The United States. They were the first people known to live in the Grand Canyon area. The cultural group has often been referred to in archaeology as the Anasazi, although the term is not preferred by the modern Puebloan peoples . The word "Anasazi" is Navajo for "enemy ancestors" or "alien ancestors". Archaeologists still debate when this distinct culture emerged. The current consensus, based on terminology defined by

4675-437: The Virgin River and continued east into Arizona, traveling along the Grand Canyon and making short exploratory side trips along the way. Walker is reported to have said he wanted to visit the "Moqui" (Hopi) Indians. who he had met briefly before and found exceptionally interesting. In 1858, John Strong Newberry became probably the first geologist to visit the Grand Canyon. In 1869, Major John Wesley Powell set out to explore

4760-512: The canyon walls, in a process known as frost wedging. Canyon walls are often formed of resistant sandstones or granite . Sometimes large rivers run through canyons as the result of gradual geological uplift. These are called entrenched rivers , because they are unable to easily alter their course. In the United States, the Colorado River in the Southwest and the Snake River in the Northwest are two examples of tectonic uplift . Canyons often form in areas of limestone rock. As limestone

4845-408: The down-cutting of the tributaries and retreat of the cliffs, simultaneously deepening and widening the canyon. For thousands of years, the area has been continuously inhabited by Native Americans, who built settlements within the canyon and its many caves. The Pueblo people considered the Grand Canyon a holy site, and made pilgrimages to it. The first European known to have viewed the Grand Canyon

4930-546: The early part of the 20th century, important articles published in Science included papers on fruit fly genetics by Thomas Hunt Morgan , gravitational lensing by Albert Einstein , and spiral nebulae by Edwin Hubble . After Cattell died in 1944, the ownership of the journal was transferred to the AAAS. After Cattell's death in 1944, the journal lacked a consistent editorial presence until Graham DuShane became editor in 1956. In 1958, under DuShane's leadership, Science absorbed The Scientific Monthly , thus increasing

5015-445: The editor of Science in 2000. Biochemist Bruce Alberts took his place in March 2008. Geophysicist Marcia McNutt became editor-in-chief in June 2013. During her tenure the family of journals expanded to include Science Robotics and Science Immunology , and open access publishing with Science Advances . Jeremy M. Berg became editor-in-chief on July 1, 2016. Former Washington University in St. Louis Provost Holden Thorp

5100-425: The expedition on foot in an attempt to reach a settlement 75 miles (121 km) away. Ironically, the remaining members went safely through the rapids on August 29, 1869, while Seneca Howland, Oramel Howland, and William H. Dunn were murdered. The area through which the three men traveled was marked by tensions between farming and hunting Shivwits and incoming Mormon settlers. Which group was responsible for killing

5185-447: The financial relationship, at a time when his reputation was suffering due to delays producing the promised commercially viable light bulb.) However, the journal never gained enough subscribers to succeed and ended publication in March 1882. Alexander Graham Bell and Gardiner Greene Hubbard bought the magazine rights and hired young entomologist Samuel H. Scudder to resurrect the journal one year later. They had some success while covering

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5270-498: The geologic origins of the Grand Canyon and the Colorado River. Formation of the Grand Canyon and the Colorado River may involve a complex history in which multiple factors and geologic processes have interacted over time and in different locations. In the most recent round of "old river" vs. "young river" controversy, researchers have challenged estimates that had placed the age of the canyon at 5–6   million years. The research has aroused considerable controversy because it suggests

5355-590: The journal's circulation by over 62% from 38,000 to more than 61,000. Physicist Philip Abelson , a co-discoverer of neptunium , served as editor from 1962 to 1984. Under Abelson the efficiency of the review process was improved and the publication practices were brought up to date. During this time, papers on the Apollo program missions and some of the earliest reports on AIDS were published. Biochemist Daniel E. Koshland Jr. served as editor from 1985 until 1995. From 1995 until 2000, neuroscientist Floyd E. Bloom held that position. Biologist Donald Kennedy became

5440-427: The lower end of Black Canyon on March 8, 1858, then continued on by rowboat past the mouth of the Virgin River after the Explorer struck a rock. Ives led his party east into the canyon – they may have been the first Europeans to travel the Diamond Creek drainage. In his "Report Upon the Colorado River of the West" to the Senate in 1861 Ives states that "The marvellous story of Cardinas , that had formed for so long

5525-424: The meetings of prominent American scientific societies, including the AAAS. However, by 1894, Science was again in financial difficulty and was sold to psychologist James McKeen Cattell for $ 500 (equivalent to $ 17,610 in 2023). In an agreement worked out by Cattell and AAAS secretary Leland O. Howard , Science became the journal of the American Association for the Advancement of Science in 1900. During

5610-555: The monument as a U.S. National Park for 11 years. Grand Canyon National Park was finally established as the 17th U.S. National Park by an Act of Congress signed into law by President Woodrow Wilson on February 26, 1919. The federal government administrators who manage park resources face many challenges. These include issues related to the recent reintroduction into the wild of the highly endangered California condor , air tour overflight noise levels, water rights and management disputes, and forest fire management. The canyon's ecosystem

5695-420: The most notable canyons of the world, grouped by region. Venus has many craters and canyons on its surface. The troughs on the planet are part of a system of canyons that is more than 6,400 km long. [REDACTED] Environment portal Science (journal) Science is the peer-reviewed academic journal of the American Association for the Advancement of Science (AAAS) and one of

5780-413: The party admitted that he never before saw anything to match or equal this astonishing natural curiosity." Also in 1857, the U.S. War Department asked Lieutenant Joseph Ives to lead an expedition to assess the feasibility of an up-river navigation from the Gulf of California. On December 31, 1857, Ives embarked from the mouth of the Colorado in the stern wheeler steamboat Explorer . His party reached

5865-422: The river's base level (its lowest point). This increased the rate of erosion and cut nearly all of the Grand Canyon's current depth by 1.2   million years ago. The terraced walls of the canyon were created by differential erosion . Between 100,000 and 3   million years ago, volcanic activity deposited ash and lava over the area, which at times completely obstructed the river. These volcanic rocks are

5950-520: The second Director of the US Geological Survey (1881–1894). He was the first to use the term "Grand Canyon", in 1871; previously it had been called the "Big Canyon". In 1889, Frank M. Brown wanted to build a railroad along the Colorado River to carry coal. He, his chief engineer Robert Brewster Stanton , and 14 others started to explore the Grand Canyon in poorly designed cedar wood boats, with no life preservers. Brown drowned in an accident near Marble Canyon : Stanton made new boats and proceeded to explore

6035-414: The three men has been hotly debated. Powell himself visited the area the following year, and was told (through a Mormon interpreter) that the Shivwits had mistakenly killed the men, believing them to be prospectors who had murdered an Indian woman. He chose to smoke a peace pipe with them. Powell went on to become the first Director of the U.S. Bureau of Ethnology of the Smithsonian Institution (1879–1902) and

6120-467: The time of the arrival of Europeans in the 16th   century, newer cultures had evolved. The Hualapai inhabit a 100-mile (160 km) stretch along the pine-clad southern side of the Grand Canyon. The Havasupai have been living in the area near Cataract Canyon since the beginning of the 13th   century, occupying an area the size of Delaware . The Southern Paiutes live in what is now southern Utah and northern Arizona. The Navajo , or Diné, live in

6205-654: The two-billion-year-old Vishnu Schist at the bottom of the Inner Gorge to the 270-million-year-old Kaibab Limestone on the Rim. Within that there is a gap, the Great Unconformity , between 1.75   billion and 1.25   billion years ago for which no deposits are present. Then, between 1.25   billion and 730   million years ago, intermittent sediments began to form the Grand Canyon Supergroup . Many of

6290-469: The underlying aquifers. Almost half of the Kaibab plateau's surface was associated with high to very high vulnerability of the unconfined Coconino aquifer (C-aquifer), while about a fifth of the Kaibab Plateau was estimated to be an area of high vulnerability for the Redwall-Muav aquifer (R-aquifer). The Ancestral Puebloans were a Native American culture centered on the present-day Four Corners area of

6375-456: The valley walls. Canyons are much more common in arid areas than in wet areas because physical weathering has a more localized effect in arid zones. The wind and water from the river combine to erode and cut away less resistant materials such as shales . The freezing and expansion of water also serves to help form canyons. Water seeps into cracks between the rocks and freezes, pushing the rocks apart and eventually causing large chunks to break off

6460-429: The waterway now traversed by the Colorado River. Of the three central segments, the "Hurricane" was formed 50–70   million years ago, and the "Eastern Grand Canyon" was cut 15–25   million years ago. In contrast, the "Marble Canyon" and "Westernmost Grand Canyon" segments at the ends of the canyon were carved in the last five to six million years. The major geologic exposures in the Grand Canyon range in age from

6545-579: The way into the canyon until they were forced to return because of lack of water. In their report, they noted that some of the rocks in the canyon were "bigger than the great tower of Seville, Giralda ". It is speculated that their Hopi guides likely knew routes to the canyon floor, but may have been reluctant to lead the Spanish to the river. No Europeans visited the canyon again for more than two hundred years. Fathers Francisco Atanasio Domínguez and Silvestre Vélez de Escalante were two Spanish priests who, with

6630-590: The west of the Grand Canyon, between 500 and 1200  CE . The Cohonina were ancestors of the Yuman , Havasupai , and Hualapai peoples who inhabit the area today. The Sinagua were a cultural group occupying an area to the southeast of the Grand Canyon, between the Little Colorado River and the Salt River , between approximately 500 and 1425 CE . The Sinagua may have been ancestors of several Hopi clans. By

6715-507: The world's top academic journals. It was first published in 1880, is currently circulated weekly and has a subscriber base of around 130,000. Because institutional subscriptions and online access serve a larger audience, its estimated readership is over 400,000 people. Science is based in Washington, D.C., United States, with a second office in Cambridge , UK. The major focus of the journal

6800-591: The youngest in the canyon. Groundwater flow in the Grand Canyon region is an active area of study. Groundwater forms when rain soaks down into the earth and reaches the water table . The composition of the earth in a given area determines its permeability , the ease with which water flows through it. Sand is more permeable than clay. Less permeable rock layers composed of clay can block the passage of water and are known as aquitards . More permeable areas of rock that hold and transport groundwater underground are known as aquifers . An area of water bounded by two aquitards

6885-449: Was García López de Cárdenas from Spain, who arrived in 1540. The Grand Canyon is a river valley in the Colorado Plateau that exposes uplifted Proterozoic and Paleozoic strata, and it is also one of the six distinct physiographic sections of the Colorado Plateau province. Even though it is not the deepest canyon in the world ( Kali Gandaki Gorge in Nepal is much deeper), the Grand Canyon

6970-570: Was named editor-in-chief on Monday, August 19, 2019. In February 2001, draft results of the human genome were simultaneously published by Nature and Science with Science publishing the Celera Genomics paper and Nature publishing the publicly funded Human Genome Project . In 2007, Science (together with Nature ) received the Prince of Asturias Award for Communications and Humanity. In 2015, Rush D. Holt Jr. , chief executive officer of

7055-467: Was permanently changed after the construction of the Glen Canyon Dam in 1963. Average flood levels dropped from 85,000 to 8,000 cubic ft/sec. In the absence of natural flooding, sandbars and beaches eroded and invasive species began to displace native species. Federal officials started releasing floods in the Grand Canyon in hopes of restoring its ecosystem beginning with 1996, 2004, and 2008. In 2018,

7140-474: Was superintendent of an expedition to survey a wagon road along the 35th parallel from Fort Defiance, Arizona to the Colorado River. He led a small party of men in search of water on the Coconino Plateau near the canyon's south rim. On September 19, near present-day National Canyon, they came upon what May Humphreys Stacey described in his journal as "a wonderful canyon; four thousand feet deep. Everybody in

7225-575: Was upheld by the U.S. District Court for Arizona in 2014, but appealed in November 2014 as National Mining Association v. Jewell (No. 14-17350). The 9th Circuit Court of Appeals again upheld the moratorium in 2017, stating that the Secretary of the Interior held valid withdrawal authority. Havasupai Tribe v. Provencio was also argued at multiple court levels based on multiple grounds. The Havasupai people and

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