搜尋結果
其他人也問了
Where is Grand Canyon national park located?
Where is Grand Park located?
Where can I find information about Grand Canyon National Park?
When did the Grand Canyon become a National Park?
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.
Gloria Molina Grand Park, commonly known as Grand Park, is a 12-acre (4.9 ha) park located in the civic center of Los Angeles, California.
- Overview
- Geologic history
Grand Canyon, immense canyon cut by the Colorado River in the high plateau region of northwestern Arizona, U.S., noted for its fantastic shapes and coloration.
The Grand Canyon lies in the southwestern portion of the Colorado Plateau, which occupies a large area of the southwestern United States and consists essentially of horizontal layered rocks and lava flows. The broad, intricately sculptured chasm of the canyon contains between its outer walls a multitude of imposing peaks, buttes, gorges, and ravines. It ranges in width from about 175 yards (160 metres) to 18 miles (29 km) and extends in a winding course from the mouth of the Paria River, near Lees Ferry and the northern boundary of Arizona with Utah, to Grand Wash Cliffs, near the Nevada state line, a distance of about 277 miles (446 km); the first portion of the canyon—from Lees Ferry to the confluence with the Little Colorado River—is called Marble Canyon. The Grand Canyon also includes many tributary side canyons and surrounding plateaus.
Although its awesome grandeur and beauty are the major attractions of the Grand Canyon, perhaps its most vital and valuable aspect lies in the time scale of Earth history that is revealed in the exposed rocks of the canyon walls. No other place on Earth compares to the Grand Canyon for its extensive and profound record of geologic events. The canyon’s record, however, is far from continuous and complete. There are immense time gaps; many millions of years are unaccounted for, owing to gaps in the strata that resulted either from vast quantities of materials being removed by erosion or because there was little or no deposition of materials. Thus, rock formations of considerably different ages are separated by only a thin distinct surface that reveals the vast unconformity in time.
Britannica Quiz
Which Is Taller? Quiz
Briefly summarized, the geologic history of the canyon strata is as follows. The crystallized, twisted, and contorted unstratified rocks of the inner gorge at the bottom of the canyon are Archean granite and schist more than 2.5 billion years old. Overlying those very ancient rocks is a layer of Proterozoic limestones, sandstones, and shales that are more than 540 million years old. On top of them are Paleozoic rock strata composed of more limestones, freshwater shales, and cemented sandstones that form much of the canyon’s walls and represent a depositional period stretching over 300 million years. Overlying those rocks in the ordinary geologic record should be a thick sequence of Mesozoic rocks (about 250 to 65 million years old), but rocks dating from the Mesozoic Era in the Grand Canyon have been entirely eroded away. Mesozoic rocks are found nonetheless in nearby southern Utah, where they form precipitous butte remnants and vermilion, white, and pink cliff terraces. Of relatively recent origin are overlying sheets of black lava and volcanic cones that occur a few miles southeast of the canyon and in the western Grand Canyon proper, some estimated to have been active within the past 1,000 years. (See also Grand Canyon Series.)
The cutting of the mile-deep Grand Canyon by the Colorado River is an event of relatively recent geologic history that began not more than six million years ago, when the river began following its present course. The Colorado River’s rapid velocity and large volume and the great amounts of mud, sand, and gravel it carries swiftly downstream account for the incredible cutting capacity of the river. Before Glen Canyon Dam was built, the sediments carried by the Colorado River were measured at an average of 500,000 tons per day. Conditions favourable to vigorous erosion were brought about by the uplift of the region, which steepened the river’s path and allowed deep entrenchment. The depth of the Grand Canyon is the result of the cutting action of the river, but its great width is explained by rain, wind, temperature, and chemical erosion, helped by the rapid wear of soft rocks, all of which steadily widened the canyon. An experiment was conducted in March 2008, in which water equivalent to about 40 percent of the river’s original flow was released from Glen Canyon Dam for a period of 60 hours to measure the erosion and deposition of sediments along the river. Researchers monitoring the experiment noted additional sand deposition at numerous locations along the river following the release.
Students save 67%! Learn more about our special academic rate today.
- The Editors of Encyclopaedia Britannica
2024年7月14日 · Entirely within the state of Arizona, the park encompasses 278 miles (447 km) of the Colorado River and adjacent uplands. Located on the ancestral homelands of 11 present day Tribal Communities, Grand Canyon is one of the most spectacular examples of erosion anywhere in the world—a mile deep canyon unmatched in the incomparable ...
- PO Box 129, Grand Canyon, 86023, AZ
2019年3月15日 · Fast Facts. Established: 1919. Size: 1.2 million acres (4,856.23 sq km) Annual Visitors: 6.2 million. Visitor Centers: South Rim, North Rim. Entrance Fees: $30 per vehicle; $15 per individual....
The Grand Canyon[a] 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). [6]: 902.
4 天前 · Grand Canyon National Park, in northern Arizona, encompasses 278 miles (447 km) of the Colorado River and adjacent uplands. Located on the ancestral homeland of 11 Associated Tribes, Grand Canyon is one of the most spectacular examples of erosion anywhere in the world—unmatched in the incomparable vistas it offers visitors on the rim.
