Colorado River in the context of Cataract Canyon

Southern California (commonly shortened to SoCal) is a geographic and cultural region that generally comprises the southern portion of the U.S. state of California. Its densely populated coastal region includes Greater Los Angeles (the second-most populous urban agglomeration in the United States) and San Diego County (the second-most populous county in California). The region generally contains ten of California's 58 counties: Los Angeles, San Diego, Orange, Riverside, San Bernardino, Kern, Ventura, Santa Barbara, San Luis Obispo, and Imperial counties.

Although geographically smaller than Northern California in land area, Southern California has a higher population, with 23.76 million residents as of the 2020 census. The sparsely populated desert region of California occupies a significant portion of the area: the Colorado Desert, along with the Colorado River, is located on Southern California's eastern border with Arizona, and the Mojave Desert shares a border with Nevada to the northeast. Southern California's southern border with Baja California is part of the Mexico–United States border.

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, the Hualapai Indian Reservation, the Havasupai Indian Reservation and the Navajo Nation. 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.

An aqueduct is a watercourse constructed to carry water from a source to a distribution point far away. In modern engineering, the term aqueduct is used for any system of pipes, ditches, canals, tunnels, and other structures used for this purpose. The term aqueduct also often refers specifically to a bridge carrying an artificial watercourse.

Aqueducts were used in ancient Greece, the ancient Near East, ancient Rome, ancient Aztec, and ancient Inca. The simplest aqueducts are small ditches cut into the earth. Much larger channels may be used in modern aqueducts. Aqueducts sometimes run for some or all of their path through tunnels constructed underground. Modern aqueducts may also use pipelines. Historically, agricultural societies have constructed aqueducts to irrigate crops and supply large cities with drinking water.

The Rio Grande (/ˌriːoʊ ˈɡrænd/ or /ˌriːoʊ ˈɡrɑːndeɪ/) in the United States or the Río Bravo (del Norte) in Mexico (Spanish pronunciation: [ˈri.o ˈβɾaβo ðel ˈnoɾte]), also known as Tó Ba'áadi in Navajo, is one of the principal rivers (along with the Colorado River) in the Southwestern United States and in northern Mexico. The length of the Rio Grande is 1,896 miles (3,051 km), making it the 4th longest river in the United States and in North America by main stem. It originates in south-central Colorado, in the United States, and flows to the Gulf of Mexico. The Rio Grande drainage basin (watershed) has an area of 182,200 square miles (472,000 km); however, the endorheic basins that are adjacent to and within the greater drainage basin of the Rio Grande increase the total drainage-basin area to 336,000 square miles (870,000 km).

The Rio Grande with its fertile valley, along with its tributaries, is a vital water source for seven U.S. and Mexican states, and flows primarily through arid and semi-arid lands. After traversing the length of New Mexico, the Rio Grande becomes the Mexico–United States border, between the U.S. state of Texas and the northern Mexican states of Chihuahua and Coahuila, Nuevo León and Tamaulipas; a short segment of the Rio Grande is a partial state-boundary between the U.S. states of New Mexico and Texas. Since the mid–twentieth century, only 20 percent of the Rio Grande's water reaches the Gulf of Mexico, because of the voluminous consumption of water required to irrigate farmland (e.g. the Mesilla and Lower Rio Grande Valleys) and to continually hydrate cities (e.g. Albuquerque); such water usages are additional to the reservoirs of water retained with diversion dams. 260 miles (418 km) of the river in New Mexico and Texas are designated as the Rio Grande Wild and Scenic River.

The Southern Rocky Mountains are a major subregion of the Rocky Mountains of North America located in the southeastern portion of the U.S. state of Wyoming, the central and western portions of Colorado, the northern portion of New Mexico, and extreme eastern portions of Utah. The Southern Rocky Mountains are also commonly known as the Southern Rockies, and since the highest peaks are located in the State of Colorado, they are sometimes known as the Colorado Rockies, although many important ranges and peaks rise in the other three states. The Southern Rockies include the highest mountain ranges of the Rocky Mountains and include all 30 of the highest major peaks of the Rockies.

The Southern Rocky Mountains are generally divided from the Western Rocky Mountains by the Green River and the Colorado River below the Green River. The Southern Rockies are divided from the Central Rocky Mountains by South Pass in Wyoming and the drainage running east from the pass down the Sweetwater River and the North Platte River; and the drainage running southwest from the pass down Pacific Creek and Sandy Creek to the Green River. This divide between the Southern Rockies and the Central Rockies provided the lowest elevation traverse of the Rocky Mountain region for the historic Oregon Trail, the Mormon Trail, and the California Trail. The southern end of the Rocky Mountains are considered to be the Jemez Mountains and the southern Sangre de Cristo Mountains of New Mexico. Mountains south of here in N.M. are classified as the Arizona/New Mexico Mountains ecoregion using the EPA Ecoregions System.

A canyon (from Spanish cañón; archaic British English spelling: cañon), gorge or chasm, is a deep cleft between escarpments or cliffs resulting from weathering and the erosive activity of a river over geologic time scales. Rivers have a natural tendency to cut through underlying surfaces, eventually wearing away rock layers as sediments are removed downstream. A river bed will gradually reach a baseline elevation, which is the same elevation as the body of water into which the river drains. The processes of weathering and erosion will form canyons when the river's headwaters and estuary are at significantly different elevations, particularly through regions where softer rock layers are intermingled with harder layers more resistant to weathering.

A canyon may also refer to 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.

Arches National Park is a national park of the United States in eastern Utah. The park is adjacent to the Colorado River, 4 mi (6 km) north of Moab, Utah. The park contains more than 2,000 natural sandstone arches, including the well-known Delicate Arch, which constitute the highest density of natural arches in the world. It also contains a variety of other unique geological resources and formations. The national park lies above an underground evaporite layer or salt bed, which is the main cause of the formation of the arches, spires, balanced rocks, sandstone fins, and eroded monoliths in the area.

The park consists of 310.31 km (76,680 acres; 119.81 sq mi; 31,031 ha) of high desert located on the Colorado Plateau. The highest elevation in the park is 5,653 ft (1,723 m) at Elephant Butte, and the lowest elevation is 4,085 ft (1,245 m) at the visitor center. The park receives an average of less than 10 in (250 mm) of rain annually.

Fortification Rock, once a landmark hill on the Colorado River before it was inundated, now known as Rock Island, southernmost and tallest of the Boulder Islands in Lake Mead, Clark County, Nevada. It has an elevation of 1284 feet. Fortification Rock appears on the 1861 Geological Map No. 1; Rio Colorado of the West, explored by 1st Lieut. Joseph C. Ives, which shows Fortification Rock, Ives Camp #59 and the course of the Colorado River from its mouth on the Gulf of California to Las Vegas Wash and the location of its features and other expedition camps along the way.

The Gulf of California (Spanish: Golfo de California), also known as the Sea of Cortés (Mar de Cortés) or Sea of Cortez, or less commonly as the Vermilion Sea (Mar Vermejo), is a marginal sea of the Pacific Ocean that separates the Baja California peninsula from the Mexican mainland. It is bordered by the states of Baja California, Baja California Sur, Sonora, and Sinaloa with a coastline of approximately 4,000 km (2,500 mi). Rivers that flow into the Gulf of California include the Colorado, Fuerte, Mayo, Sinaloa, Sonora, and the Yaqui. The surface of the gulf is about 160,000 km (62,000 sq mi). Maximum depths exceed 3,000 meters (9,800 ft) because of the complex geology, linked to plate tectonics.

The gulf is thought to be one of the most diverse seas on Earth and is home to more than 5,000 species of micro-invertebrates. Parts of the Gulf of California are a UNESCO World Heritage Site.

Brachiosaurus (/ˌbrækiəˈsɔːrəs/) is a genus of sauropod dinosaur that lived in North America during the Late Jurassic, about 155.6 to 145.5 million years ago. It was first described by American paleontologist Elmer S. Riggs in 1903 from fossils found in the Colorado River valley in western Colorado, United States. Riggs named the dinosaur Brachiosaurus altithorax; the generic name is Greek for "arm lizard", in reference to its proportionately long arms, and the specific name means "deep chest". Brachiosaurus is estimated to have been between 18 and 22 meters (59 and 72 ft) long; body mass estimates of the subadult holotype specimen range from 28.3 to 46.9 metric tons (31.2 to 51.7 short tons). It had a disproportionately long neck, small skull, and large overall size, all of which are typical for sauropods. Atypically, Brachiosaurus had longer forelimbs than hindlimbs, which resulted in a steeply inclined trunk, and a proportionally shorter tail.

Brachiosaurus is the namesake genus of the family Brachiosauridae, which includes a handful of other similar sauropods. Most popular depictions of Brachiosaurus are in fact based on Giraffatitan, a genus of brachiosaurid dinosaur from the Tendaguru Formation of Tanzania. Giraffatitan was originally described by German paleontologist Werner Janensch in 1914 as a species of Brachiosaurus, B. brancai, but moved to its own genus in 2009. Three other species of Brachiosaurus have been named based on fossils found in Africa and Europe; two are no longer considered valid, and a third has become a separate genus, Lusotitan.

The Colorado River Delta is the region where the Colorado River once flowed into the Gulf of California (also known as the Sea of Cortez) in eastern Mexicali Municipality in the north of the state of Baja California, in northwestern Mexico. The delta is part of a larger geologic region called the Salton Trough. Historically, the interaction of the river's flow and the ocean's tide created a dynamic environment, supporting freshwater, brackish, and saltwater species. Within the delta region, the river split into multiple braided channels and formed a complex estuary and terrestrial ecosystems. The use of water upstream and the accompanying reduction of freshwater flow has resulted in the loss of most of the wetlands of the area, as well as drastic changes to the aquatic ecosystems - an ecosystem collapse.

John Wesley Powell (March 24, 1834 – September 23, 1902) was an American geologist, U.S. Army soldier, explorer of the American West, professor at Illinois Wesleyan University, and director of major scientific and cultural institutions. He is famous for his 1869 geographic expedition, a three-month river trip down the Green and Colorado rivers, including the first official U.S. government-sponsored passage through the Grand Canyon.

Powell was appointed by US President James A. Garfield to serve as the second director of the U.S. Geological Survey (1881–1894) and proposed, for development of the arid West, policies that were prescient for his accurate evaluation of conditions. Two years prior to his service as director of the U.S. Geological Survey, Major Powell had become the first director of the Bureau of Ethnology at the Smithsonian Institution where he supported linguistic and sociological research and publications.

Grand Canyon National Park is a national park of the United States located in northwestern Arizona, the 15th site to have been named as 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 4.9 million recreational visitors in 2024. The Grand Canyon was designated a World Heritage Site by UNESCO in 1979. The park celebrated its 100th anniversary on February 26, 2019.

The Hualapai (/ˈwɑːlɑːpaɪ/ WAH-lah-py, Walapai: Hwalbáy) are a federally recognized Native American tribe in Arizona with about 2300 enrolled citizens. Approximately 1353 enrolled citizens reside on the Hualapai Reservation, which spans over three counties in Northern Arizona (Coconino, Yavapai, and Mohave).

The name, meaning "people of the tall pines", is derived from hwa:l, the Hualapai word for ponderosa pine and pai "people". Their traditional territory is a 108-mile (174 km) stretch along the pine-clad southern side of the Grand Canyon and the Colorado River with the tribal capital at Peach Springs. Other communities on the reservation include Valentine and Grand Canyon West.

Numic is the northernmost branch of the Uto-Aztecan language family. It includes seven languages spoken by Native American peoples traditionally living in the Great Basin, Colorado River basin, Snake River basin, and southern Great Plains. The word "Numic" comes from the cognate word in all Numic languages for "person", which reconstructs to Proto-Numic as /*nɨmɨ/. For example, in the three Central Numic languages and the two Western Numic languages, the word for "person" is /nɨmɨ/. In Kawaiisu it is /nɨwɨ/, and in Colorado River, it is /nɨwɨ/, /nɨŋwɨ/, and /nuu/.

The Colorado Plateau is a physiographic and desert region of the Intermontane Plateaus, roughly centered on the Four Corners region of the Southwestern United States. This plateau covers an area of 336,700 km (130,000 mi) within western Colorado, northwestern New Mexico, southern and eastern Utah, northern Arizona, and a tiny fraction in the extreme southeast of Nevada. About 90% of the area is drained by the Colorado River and its main tributaries: the Green, San Juan, and Little Colorado. Most of the remainder of the plateau is drained by the Rio Grande and its tributaries.

The Colorado Plateau is largely made up of high desert, with scattered areas of forests. In the south-west corner of the Colorado Plateau, nicknamed High Country, lies the Grand Canyon of the Colorado River. Much of the Plateau's landscape is related to the Grand Canyon in both appearance and geologic history. The nickname "Red Rock Country" suggests the brightly colored rock left bare to the view by dryness and erosion. Domes, hoodoos, fins, reefs, river narrows, natural bridges, and slot canyons are only some of the additional features typical of the Plateau.

Canyonlands National Park is a national park of the United States located in southeastern Utah near the town of Moab. The park preserves a colorful landscape eroded into numerous canyons, mesas, and buttes by the Colorado River, the Green River, and their respective tributaries. Legislation creating the park was signed into law by President Lyndon B. Johnson on September 12, 1964.

The park is divided into four districts: the Island in the Sky, the Needles, the Maze, and the combined rivers—the Green and Colorado—which carved two large canyons into the Colorado Plateau. While these areas share a primitive desert atmosphere, each retains its own character. Author Edward Abbey, a frequent visitor, described the Canyonlands as "the most weird, wonderful, magical place on earth—there is nothing else like it anywhere."