paragraph_text: Grand Canyon National Park, located in northwestern Arizona, is the 15th site in the United States to have been named a national park. The park's central feature is the Grand Canyon, a gorge of the Colorado River, which is often considered one of the Wonders of the World. The park, which covers 1,217,262 acres (1,901.972 sq mi; 4,926.08 km) of unincorporated area in Coconino and Mohave counties, received more than six million recreational visitors in 2017, which is the second highest count of all American national parks after Great Smoky Mountains National Park. The Grand Canyon was designated a World Heritage Site by UNESCO in 1979.

paragraph_text: The Marimbondo Dam is an embankment dam on the Grande River near Fronteira in Minas Gerais, Brazil. The dam serves an associated hydroelectric power plant with a installed capacity.

paragraph_text: Inniscarra Dam is a buttress dam located on the River Lee in County Cork, Ireland. Construction of the dam started in February 1953. It is owned and operated by the ESB Group. It has a generation capacity of 19 MW.

paragraph_text: The Grand Canyon is a river valley in the Colorado Plateau that exposes uplifted Proterozoic and Paleozoic strata, and is also one of the six distinct physiographic sections of the Colorado Plateau province. It is not the deepest canyon in the world (Kali Gandaki Gorge in Nepal is much deeper). However, the Grand Canyon 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.

paragraph_text: Since about 1900, the Black Canyon and nearby Boulder Canyon had been investigated for their potential to support a dam that would control floods, provide irrigation water and produce hydroelectric power. In 1928, Congress authorized the project. The winning bid to build the dam was submitted by a consortium called Six Companies, Inc., which began construction on the dam in early 1931. Such a large concrete structure had never been built before, and some of the techniques were unproven. The torrid summer weather and lack of facilities near the site also presented difficulties. Nevertheless, Six Companies turned over the dam to the federal government on March 1, 1936, more than two years ahead of schedule.

paragraph_text: Byers Canyon is a short gorge on the upper Colorado River in Grand County, Colorado in the United States. The canyon is approximately 8 miles (13 km) long and is located in the headwaters region of the Colorado between Hot Sulphur Springs and Kremmling. U.S. Highway 40 passes through the canyon between Hot Sulphur Springs and Kremmling. The Union Pacific Railroad's Moffat Route also travels through the short canyon.

paragraph_text: The Town of Cedaredge is a Home Rule Municipality in Delta County, Colorado, United States. The town population was 2253 at the 2010 United States Census. Cedaredge sits in the Surface Creek Valley beneath the southern slopes of the Grand Mesa, the largest mesa in the world. Its elevated vantage point affords southern views of the San Juan Mountains, the Black Canyon of the Gunnison National Park, and the communities of Delta, Olathe, and Montrose. Cedaredge is a small, agricultural community which produces beef cattle, apples, peaches, and wine from the region's few basic vineyards. Tourist attractions include Cedaredge Golf Club, Historic Pioneer Town, and an art gallery and craft store housed in a renovated apple packing shed. Regional sporting activities include camping, trophy hunting, hiking and Gold Medal fishing at more than 250 lakes on the Grand Mesa. During the winter locals partake in snowmobiling and Nordic skiing on the Mesa's trails. Powderhorn Resort is located north of Cedaredge and has ski terrain such as groomers, bumps, glades, and boulder fields, as well as two terrain parks.

paragraph_text: The Grand Canyon North Rim Headquarters is a historic district on the North Rim of the Grand Canyon in Grand Canyon National Park, Arizona. Established from 1926 through the 1930s, the district includes examples of National Park Service Rustic architecture as applied to employee residences, administrative facilities and service structures.

paragraph_text: Ohrigstad River is located in Mpumalanga, South Africa. The Ohrigstad River joins the Blyde River at the Blyderivierpoort Dam in the Blyde River Canyon Nature Reserve. Like the Blyde, it has its ultimate origin at around 2,000 m altitude to the south, on the verge of the Hartebeesvlakte conservation area, but follows a more westerly course.

paragraph_text: Cimarron Hydroelectric Power Project a hydroelectric power plant in El Salvador, that was to start construction in 2010. The plant would have been be located in the upper basin of the Lempa River, upstream of the Cerrón Grande Hydroelectric Dam. The proposed location of the dam was between the towns of Agua Caliente, Chalatenango on the left shore and Metapán, Santa Ana, on the right shore. A tunnel would divert water from the Lempa River to a powerhouse and substation to be built near Agua Caliente. With an estimated capacity of 261 megawatts, the project would have increased El Salvador's total generation capacity by almost 25%.

paragraph_text: Thistle is a ghost town in Spanish Fork Canyon in southeastern Utah County, Utah, United States. During the era of steam locomotives, the town's primary industry was servicing trains for the Denver and Rio Grande Western Railroad (often shortened to D&RG, D&RGW, or Rio Grande). The fortunes of the town were closely linked with those of the railroad until the changeover to diesel locomotives, when the town started to decline.

paragraph_text: The Messina Chasmata are the largest canyon or system of canyons on the surface of the Uranian moon Titania, named after a location in William Shakespeare's comedy Much Ado About Nothing. The 1492 km long feature includes two normal faults running NW–SE, which bound a down-dropped crustal block forming a structure called a graben. The graben cuts impact craters, which probably means that it was formed at a relatively late stage of the moon's evolution, when the interior of Titania expanded and its ice crust cracked as a result. The Messina Chasmata have only a few superimposed craters, which also implies being relatively young. The feature was first imaged by Voyager 2 in January 1986.

paragraph_text: Hopi House is located on the South Rim of the Grand Canyon, within Grand Canyon National Park in the U.S. state of Arizona. Built in 1904 as concessioner facilities at the South Rim were being developed, it is the first of eight projects at the Grand Canyon that were designed by architect Mary Colter, along with Bright Angel Lodge, Hermit's Rest, Lookout Studio, Phantom Ranch, Desert View Watchtower, Colter Hall and Victor Hall, (the latter two being employee dormitories). Hopi House was built by the Fred Harvey Company as a market for Native American crafts, made by artisans on the site. The Hopi, as the historic inhabitants of the area, were chosen as the featured artisans, and the building was designed to closely resemble a traditional Hopi pueblo. Hopi House opened on January 1, 1905, two weeks before the El Tovar Hotel, located just to the west, was opened.

paragraph_text: Canyon Creek is a hamlet in northern Alberta, Canada within the Municipal District of Lesser Slave River No. 124. It is located on Highway 2, approximately east of Grande Prairie.

paragraph_text: The Mill Creek Canyon Earthworks is a public park, storm water detention dam and Modernist "masterpiece" of environmental art located in Kent, Washington, Washington, United States. The earthworks was created by Bauhaus artist Herbert Bayer in 1982 and designated a landmark by King County Landmarks Commission in 2008. The earthworks site covers .

paragraph_text: The Grand Canyon (Hopi: Ongtupqa; Yavapai: Wi: kaʼi: la, Navajo: Tsékooh Hatsoh, Spanish: Gran Cañón) 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).

paragraph_text: 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 to 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.

paragraph_text: Choke Canyon Reservoir is a reservoir in South Texas, United States. The lake and the dam that creates it are owned by the United States Bureau of Reclamation and managed by the City of Corpus Christi.

paragraph_text: After a 1944 United States Mexico Treaty the Morelos Dam was built in 1950 across the Colorado River. It is located about below the junction of the California border and the Colorado River between the town of Los Algodones, Baja California, in northwestern Mexico and Yuma County, Arizona in the southwestern United States. The eastern half of the dam lies inside United States territory; but Mexico is responsible for all maintenance. The dam allows Mexico to divert its allotted water from the Colorado River to highly developed crop lands in the Mexicali, Mexico Valley. The Morelos Dam is the final dam on the Colorado River. It is run by the International Boundary and Water Commission (IBWC).

paragraph_text: SS "Grand Canyon State" (T-ACS-3) is a crane ship in ready reserve for the United States Navy. The ship was named for the state of Arizona, which is also known as the "Grand Canyon State".

Question: When did the river where Morelos Dam is located start to form the Grand Canyon?
Answer: about 5 to 6 million years ago