Question: When did the river that is found to the east start to form the Grand Canyon?

full_context: Document 1: Southern California: The state is most commonly divided and promoted by its regional tourism groups as consisting of northern, central, and southern California regions. The two AAA Auto Clubs of the state, the California State Automobile Association and the Automobile Club of Southern California, choose to simplify matters by dividing the state along the lines where their jurisdictions for membership apply, as either northern or southern California, in contrast to the three-region point of view. Another influence is the geographical phrase South of the Tehachapis, which would split the southern region off at the crest of that transverse range, but in that definition, the desert portions of north Los Angeles County and eastern Kern and San Bernardino Counties would be included in the southern California region due to their remoteness from the central valley and interior desert landscape.
Document 2: Southern California: "Southern California" is not a formal geographic designation, and definitions of what constitutes southern California vary. Geographically, California's north-south midway point lies at exactly 37° 9' 58.23" latitude, around 11 miles (18 km) south of San Jose; however, this does not coincide with popular use of the term. When the state is divided into two areas (northern and southern California), the term "southern California" usually refers to the ten southern-most counties of the state. This definition coincides neatly with the county lines at 35° 47′ 28″ north latitude, which form the northern borders of San Luis Obispo, Kern, and San Bernardino counties. Another definition for southern California uses Point Conception and the Tehachapi Mountains as the northern boundary.
Document 3: Geology: All of these processes do not necessarily occur in a single environment, and do not necessarily occur in a single order. The Hawaiian Islands, for example, consist almost entirely of layered basaltic lava flows. The sedimentary sequences of the mid-continental United States and the Grand Canyon in the southwestern United States contain almost-undeformed stacks of sedimentary rocks that have remained in place since Cambrian time. Other areas are much more geologically complex. In the southwestern United States, sedimentary, volcanic, and intrusive rocks have been metamorphosed, faulted, foliated, and folded. Even older rocks, such as the Acasta gneiss of the Slave craton in northwestern Canada, the oldest known rock in the world have been metamorphosed to the point where their origin is undiscernable without laboratory analysis. In addition, these processes can occur in stages. In many places, the Grand Canyon in the southwestern United States being a very visible example, the lower rock units were metamorphosed and deformed, and then deformation ended and the upper, undeformed units were deposited. Although any amount of rock emplacement and rock deformation can occur, and they can occur any number of times, these concepts provide a guide to understanding the geological history of an area.
Document 4: Grand Canyon: 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.
Document 5: Grand Canyon: 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.
Document 6: Geography of the United States: West of the Rocky Mountains lies the Intermontane Plateaus (also known as the Intermountain West), a large, arid desert lying between the Rockies and the Cascades and Sierra Nevada ranges. The large southern portion, known as the Great Basin, consists of salt flats, drainage basins, and many small north-south mountain ranges. The Southwest is predominantly a low-lying desert region. A portion known as the Colorado Plateau, centered around the Four Corners region, is considered to have some of the most spectacular scenery in the world. It is accentuated in such national parks as Grand Canyon, Arches, Mesa Verde National Park and Bryce Canyon, among others. Other smaller Intermontane areas include the Columbia Plateau covering eastern Washington, western Idaho and northeast Oregon and the Snake River Plain in Southern Idaho.
Document 7: Geological history of Earth: The geological history of Earth follows the major events in Earth's past based on the geologic time scale, a system of chronological measurement based on the study of the planet's rock layers (stratigraphy). Earth formed about 4.54 billion years ago by accretion from the solar nebula, a disk - shaped mass of dust and gas left over from the formation of the Sun, which also created the rest of the Solar System.
Document 8: Mexico–United States border: The total length of the continental border is 1,954 miles (3,145 km). From the Gulf of Mexico, it follows the course of the Rio Grande (Río Bravo del Norte) to the border crossing at Ciudad Juárez, Chihuahua, and El Paso, Texas. Westward from El Paso -- Juárez, it crosses vast tracts of the Chihuahuan and Sonoran deserts to the Colorado River Delta and San Diego -- Tijuana, before reaching the Pacific Ocean.
Document 9: Colorado River: Colorado River The Colorado River at Horseshoe Bend, Arizona, a few miles below Glen Canyon Dam Countries United States, Mexico States Colorado, Utah, Arizona, Nevada, California, Baja California, Sonora Tributaries - left Fraser River, Blue River, Eagle River, Roaring Fork River, Gunnison River, Dolores River, San Juan River, Little Colorado River, Bill Williams River, Gila River - right Green River, Dirty Devil River, Escalante River, Kanab River, Virgin River, Hardy River Cities Glenwood Springs, CO, Grand Junction, CO, Moab, UT, Page, AZ, Bullhead City, AZ, Lake Havasu City, AZ, Yuma, AZ, San Luis Rio Colorado, SON Source La Poudre Pass - location Rocky Mountains, Colorado, United States - elevation 10,184 ft (3,104 m) - coordinates 40 ° 28 ′ 20 ''N 105 ° 49 ′ 34'' W ﻿ / ﻿ 40.47222 ° N 105.82611 ° W ﻿ / 40.47222; - 105.82611 Mouth Gulf of California - location Colorado River Delta, Baja California -- Sonora, Mexico - elevation 0 ft (0 m) - coordinates 31 ° 54 ′ 00 ''N 114 ° 57 ′ 03'' W ﻿ / ﻿ 31.90000 ° N 114.95083 ° W ﻿ / 31.90000; - 114.95083 Coordinates: 31 ° 54 ′ 00 ''N 114 ° 57 ′ 03'' W ﻿ / ﻿ 31.90000 ° N 114.95083 ° W ﻿ / 31.90000; - 114.95083 Length 1,450 mi (2,334 km) Basin 246,000 sq mi (637,137 km) Discharge for mouth (average virgin flow), max and min at Topock, AZ, 300 mi (480 km) from the mouth - average 22,500 cu ft / s (637 m / s) - max 384,000 cu ft / s (10,900 m / s) - min 422 cu ft / s (12 m / s) Map of the Colorado River basin Wikimedia Commons: Colorado River
Document 10: Candor Chasma: Candor Chasma is one of the largest canyons in the Valles Marineris canyon system on Mars. The feature is geographically divided into two halves: East and West Candor Chasmas, respectively. It is unclear how the canyon originally formed; one theory is that it was expanded and deepened by tectonic processes similar to a graben, while another suggests that it was formed by subsurface water erosion similar to a karst. MRO discovered sulfates, hydrated sulfates, and iron oxides in Candor Chasma.
Document 11: Water in California: The Colorado River originates more than 1,000 miles (1,600 km) from California in the Rocky Mountains of Colorado and Wyoming and forms the state's southeastern border in the Mojave Desert. Unlike the other California watersheds, essentially all of the water flowing in the Colorado originates outside the state. The Colorado is a critical source of irrigation and urban water for southern California, providing between 55 and 65 percent of the total supply.
Document 12: Southern California: To the east is the Colorado Desert and the Colorado River at the border with Arizona, and the Mojave Desert at the border with the state of Nevada. To the south is the Mexico–United States border.
Document 13: Outflow channels: Outflow channels are extremely long, wide swathes of scoured ground on Mars, commonly containing the streamlined remnants of pre-existing topography and other linear erosive features indicating sculpting by fluids moving downslope. Channels extend many hundreds of kilometers in length and are typically greater than one kilometer in width; the largest valley (Kasei Vallis) is around long, greater than wide and exceeds in depth cut into the surrounding plains. These features tend to appear fully sized at fractures in the Martian surface, either from chaos terrains or from canyon systems or other tectonically controlled, deep graben, though there are exceptions. Besides their exceptional size, the channels are also characterized by low sinuosities and high width:depth ratios compared both to other Martian valley features and to terrestrial river channels. Crater counts indicate that most of the channels were cut since the early Hesperian, though the age of the features is variable between different regions of Mars. Some outflow channels in the Amazonis and Elysium Planitiae regions have yielded ages of only tens of million years, extremely young by the standards of Martian topographic features.
Document 14: Geography of California: California is a U.S. state on the western coast of North America. Covering an area of , California is geographically diverse. The Sierra Nevada, the fertile farmlands of the Central Valley, and the arid Mojave Desert of the south are some of the major geographic features of this U.S. state. It is home to some of the world's most exceptional trees: the tallest (coast redwood), most massive (Giant Sequoia), and oldest (bristlecone pine). It is also home to both the highest (Mount Whitney) and lowest (Death Valley) points in the 48 contiguous states.
Document 15: Grand Canyon: 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).
ground_truth: about 5 to 6 million years ago
sub_queries: What is the name of the water body that is found to the east? Answer: Colorado River
when did Colorado River start to form the grand canyon Answer: about 5 to 6 million years ago