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The Merced River (pronounced ''mer-SED''), in the central part of the U.S. state of California, is a -long〔 tributary of the San Joaquin River flowing from the Sierra Nevada into the San Joaquin Valley. It is most well known for its swift and steep course through the southern part of Yosemite National Park, and the world-famous Yosemite Valley. The river's character changes dramatically once it reaches the foothills and the lowlands, becoming a slow-moving waterway meandering through irrigated fields. When tectonic activity first led to the uplift of the Sierra, the river formed as a steep stream eroding into the range's western flank, carrying sediments that would later help form the floor of the Central Valley. A rich riparian zone around the Merced once supported millions of migratory birds along the Pacific Flyway, and the river had one of the southernmost runs of salmon in North America. Indigenous people, including the Miwok and Paiute tribes, lived along the river for thousands of years, thriving on the bountiful flora and fauna supported by the river and its diverse lower course, aided by fertile soils eroded from the mountains. Military expeditions during the Mexican Era history of California passed through the Merced River region in the early 19th century. The California Gold Rush brought many people into California and some settled leading to the establishment of a railroad along the river, bringing minerals and lumber to towns that had been established on the lower Merced, and later provided tourism to the now-national park area. Conflicts between whites and indigenous peoples prompted wars, resulting in the expulsion of the Ahwahnechee from Yosemite Valley. In the 20th century, the river saw further development that would change its state forever. Large-scale irrigated agriculture was introduced to the Central Valley in the late 19th century, and led to the construction of numerous state, federal and privately owned dams. Water demand has often been higher than the river's environment can sustain. Salmon have been blocked from migrating and riverside habitat has declined dramatically. Recent years have seen habitat conservation work, mimicking of historic streamflow patterns, and the establishment of a salmon hatchery, in the hopes that the river's health can be protected from further damage. ==Course== The headwaters of the Merced River are at at the foot of the Clark Range, a subrange of the Sierra Nevada, rising at the confluence of the Triple Peak Fork and Merced Peak Fork after they cascade down glacially polished slopes from the high country in the southeastern corner of Yosemite National Park. the Merced River flows for westward through a series of canyons, gorges and finally the flat plains of the Central Valley. From its headwaters, the river flows north for a short distance and collects the Lyell Peak Fork. The course of the Merced then turns to the north west and flows through a steep walled canyon for where the river receives the Red Peak Fork and then collects into Washburn Lake at elevation. The Merced continues to the northwest for where collects into Merced Lake. Leaving Merced Lake, the river continues to the west northwest for where the canyons open up into Echo Valley. The river then turns generally westward for another , where it snakes through a spectacular narrow gorge between massive, glacially resistant granite cliffs. The gorge opens up after Bunnell Point and Sugarloaf Dome confine the river to form Bunnell Cascade, before turning southward through the Lost Valley of the Merced, and then spills over an unnamed granite cascade into Little Yosemite Valley, a glacial valley that sits feet above the more famous Yosemite Valley at approximately 2/3 scale. The Merced River then drops over Nevada Falls and Vernal Falls, receives Illilouette Creek, and passes into the main Yosemite Valley, where it meanders between pine forests that fill the valley floor. Tenaya, Yosemite, Bridalveil and Pigeon Creeks join the Merced before it breaches the glacial moraine at the valley's end. From there the river picks up Cascade Creek and turns south near El Portal, flowing through Merced River Canyon. State Route 140 follows the river out of the west entrance to the national park, a few miles before the South Fork Merced River, the largest tributary, joins from the left. The river arcs northwest to receive the North Fork, and a few miles after it enters Lake McClure, formed by New Exchequer Dam. Below New Exchequer, the river flows west through a heavily irrigated region of the Central Valley, passing through McSwain and Crocker-Huffman Dams and the cities of Hopeton, Delhi and Livingston. It joins the San Joaquin River at Hills Ferry, a few miles south of Turlock.〔〔〔 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Merced River」の詳細全文を読む スポンサード リンク
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