paragraph_text: The Ponte dell'Accademia is one of only four bridges to span the Grand Canal in Venice, Italy. It crosses near the southern end of the canal, and is named for the Accademia di Belle Arti di Venezia, which from 1807 to 2004 was housed in the Scuola della Carità together with the Gallerie dell'Accademia, which is still there. The bridge links the sestieri of Dorsoduro and San Marco.

paragraph_text: The Long Beach Bridge is a drawbridge crossing Reynolds Channel, connecting Long Beach and Island Park, New York. There is no toll. The bridge starts in Long Beach as Long Beach Boulevard. At Barnum Island, the main road continues northeast as Austin Boulevard, while Long Beach Road branches to the north.

paragraph_text: The William A. Jones Memorial Bridge is a bridge that spans the Pasig River in the Philippines connecting the Manila area of Binondo on Rosario Street ("Calle Rosario", now Quintin Paredes Street), with the center of city in Ermita. The previous bridge that connected the two areas was the Puente Grande (Great Bridge), later called the Puente de España (Bridge of Spain) located one block upriver on Nueva Street ("Calle Nueva", now E. T. Yuchengco Street). That span was considered as the oldest established in the Philippines.

paragraph_text: The North Grand Island Bridge is a pair of twin two-lane truss arch bridges spanning the Niagara River between Grand Island and Niagara Falls in New York, United States. Each bridge carries one direction of Interstate 190 (I-190). Both crossings are operated by the New York State Thruway Authority as part of the Niagara Thruway. The northbound span opened in 1935; the southbound span was finished in 1965.

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".

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: 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: The George Rogers Clark Memorial Bridge, known locally as the Second Street Bridge, is a four-lane cantilevered truss bridge crossing the Ohio River between Louisville, Kentucky and Jeffersonville, Indiana, that carries US 31.

paragraph_text: In Darkness and in Light is a 2011 short film distributed by Warner Bros., scripted by Ian Kintzle, from a story by Kintzle and John O'Callaghan, and directed by James Sullos and Mike Jones. The film is packaged with a boxset of music from the American rock band The Maine, and is sold exclusively on iTunes.

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: Olympic Bridge or Grand Olympic Bridge () is a bridge over the Han River in Seoul, South Korea. The bridge links the Gwangjin and Songpa districts. Its construction started in 1985, but was not completed until 1990, after the Seoul Olympic Games of 1988, because the bridge under construction had collapsed.

paragraph_text: This is a complete list of current bridges and other crossings of the Monongahela River starting from Pittsburgh, Pennsylvania, where the river helps to form the headwaters of the Ohio River, and ending in Fairmont, West Virginia, where the West Fork River and Tygart Valley River combine to form the Monongahela.

paragraph_text: Aldford Iron Bridge is a bridge crossing the River Dee north of the village of Aldford, Cheshire, England, linking the village with Eaton Hall, forming part of the Buerton Approach to the hall (). It is recorded in the National Heritage List for England as a designated Grade I listed building.

paragraph_text: Hagwilget Canyon Bridge is a suspension bridge over the Hagwilget Canyon on the Bulkley River, at the Wet'suwet'en village of Hagwilget, British Columbia. The current bridge was constructed in 1931, and later reinforced in 1990.

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 Hope Memorial Bridge (formerly the Lorain–Carnegie Bridge) is a art deco truss bridge crossing the Cuyahoga River in Cleveland, Ohio. The bridge connects Lorain Avenue on Cleveland's west side and Carnegie Avenue on the east side, terminating just short of Progressive Field. Pairs of statues designed by sculptor Henry Hering and architect Frank Walker – titled the "Guardians of Traffic" – stand on pylons at each end of the viaduct, symbolizing progress in transportation.

paragraph_text: The Burlington–Bristol Bridge is a truss bridge with a lift span crossing the Delaware River from Burlington, New Jersey to Bristol Township, Pennsylvania in the United States. Construction of the bridge started on April 1, 1930, and the bridge opened to traffic on May 2, 1931. The bridge carries NJ 413 and PA 413.

paragraph_text: The John Basilone Veterans Memorial Bridge is a bridge in New Jersey that crosses the Raritan River. The bridge was built in 2005 to replace the smaller Nevius Street Bridge built in 1886. The Nevius Street Bridge today functions as a pedestrian bridge. The bridge connects First Avenue and what used to be the short one way block of Lyman Street in Raritan with River Road in Hillsborough. After crossing into Hillsborough, the road curves to meet up with the old alignment with the Nevius Street Bridge. The bridge is named for local World War II hero, John Basilone. The bridge has a pedestrian tunnel underneath its northern approach, as part of the Raritan River Greenway.

paragraph_text: The Mike O'Callaghan–Pat Tillman Memorial Bridge is an arch bridge in the United States that spans the Colorado River between the states of Arizona and Nevada. The bridge is located within the Lake Mead National Recreation Area approximately southeast of Las Vegas, and carries Interstate 11 and U.S. Route 93 over the Colorado River. Opened in 2010, it was the key component of the Hoover Dam Bypass project, which rerouted US 93 from its previous routing along the top of Hoover Dam and removed several hairpin turns and blind curves from the route. It is jointly named for Mike O'Callaghan, Governor of Nevada from 1971–1979, and Pat Tillman, an American football player who left his career with the Arizona Cardinals to enlist in the United States Army and was later killed in Afghanistan by friendly fire.

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.

Question: When did the body of water crossed by Mike O'Callaghan–Pat Tillman Memorial Bridge start to form the grand canyon?
Answer: about 5 to 6 million years ago