through what process has the colorado river created the grand canyon in the usa
erosion
title: Grand Canyon text: the scenery. 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. For thousands of title: Grand Canyon text: The ancestral Colorado River responded by cutting its channel faster and deeper. The base level and course of the Colorado River (or its ancestral equivalent) changed 5.3 million years ago when the Gulf of California opened and lowered the river's base level (its lowest point). This increased the rate of erosion and cut nearly all of the Grand Canyon's current depth by 1.2 million years ago. The terraced walls of the canyon were created by differential erosion. Between 100,000 and 3 million years ago, volcanic activity deposited ash and lava over the area which at times completely obstructed the river. title: Grand Canyon text: The great depth of the Grand Canyon and especially the height of its strata (most of which formed below sea level) can be attributed to () of uplift of the Colorado Plateau, starting about 65 million years ago (during the Laramide Orogeny). This uplift has steepened the stream gradient of the Colorado River and its tributaries, which in turn has increased their speed and thus their ability to cut through rock (see the elevation summary of the Colorado River for present conditions). Weather conditions during the ice ages also increased the amount of water in the Colorado River drainage system. title: Colorado River text: the Grand Canyon. American explorers collected valuable information that was later used to develop the river for navigation and water supply. Large-scale settlement of the lower basin began in the mid- to late-19th century, with steamboats providing transportation from the Gulf of California to landings along the river that linked to wagon roads to the interior. Starting in the 1860s, gold and silver strikes drew prospectors to parts of the upper Colorado River basin. Large engineering works began around the start of the 20th century, with major guidelines established in a series of international and U.S. interstate treaties known as title: Grand Canyon National Park text: users." In 2010, Grand Canyon National Park was honored with its own coin under the America the Beautiful Quarters program. The Grand Canyon, including its extensive system of tributary canyons, is valued for its combination of size, depth, and exposed layers of colorful rocks dating back to Precambrian times. The canyon itself was created by the incision of the Colorado River and its tributaries after the Colorado Plateau was uplifted, causing the Colorado River system to develop along its present path. The primary public areas of the park are the South and North Rims, and adjacent areas of the canyon