These various areas of the lake have their own names. The Merced River drops over Nevada Fall and Vernal Fall, together known as the "Giant Staircase", then receives Illilouette Creek and flows into Yosemite Valley, where it meanders between pine forests and meadows that fill the valley floor. The Merced River watershed encompasses 1,726 square miles (4,470km2) in the central Sierra Nevada. Diversion of water for irrigation often reduces the river to a small stream by the time it reaches its mouth. Quick facts, basic science, and information about snow, ice, and why the cryosphere matters The cryosphere includes all of the snow and ice-covered regions across the planet. A railroad was built along the Merced canyon, enabling mining and logging in the upper watershed, and later carrying tourists to Yosemite National Park. 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 a granite cliff into Little Yosemite Valley, named for its resemblance to Yosemite Valley downstream. The meltwater at the snout of the glacier deposits its load of sediment over the outwash plain, with larger boulders being Less apparent are ground moraines, also called glacial drift, which often blankets the surface underneath the glacier downslope from the equilibrium line. [18] Extensive layers of marine sedimentary rock that originally made up the ancient Pacific seabed were also pushed up by the rising granite, and the ancestral Merced River formed on this layer of rock. Classified as a "high hazard" structure, it was originally considered for inclusion on the National Register of Historic Places but was deemed too dangerous, and was subsequently removed. [14], Many species of plants are found throughout the middle and upper basin, including California poppy, white alder, Oregon ash, oak, poison oak, bigleaf maple, Indian rhubarb, buttonbush, willow, whiteleaf manzanita, and historically, sugar pine, before heavy logging in the late 19th century. Eventually, plans to establish a mission chain in the Valley were abandoned. [19], Over about 80 million years, erosion caused the transportation of massive amounts of alluvial sediment to the floor of the Central Valley, where it was trapped between the California Coast Range on the west and the Sierra Nevada on the east, forming an incredibly flat and fertile land surface. [30] Following the construction of the Central Pacific and Southern Pacific Railroads, many of the river towns on the Merced River were deserted. This glossary of geography terms is a list of definitions of terms and concepts used in geography and related fields, including Earth science, oceanography, cartography, and human geography, as well as those describing spatial dimension, topographical features, natural resources, and the collection, analysis, and visualization of geographic data.. Related terms may be found in Triple Peak Fork, Lyell Fork, Sunrise Creek, This page was last edited on 29 October 2022, at 22:52. In 1851 the Mariposa Battalion was formed to drive the remaining Ahwahnechee out of the valley into reservations. It joins the San Joaquin River at Hills Ferry, a few miles south of Turlock.[4][5][6]. Originally built to generate hydropower, the dam was decommissioned in 1985 but remained standing for a number of years afterward. Historically, there was an extensive riparian zone which provided habitat for millions of migrating birds, and the river had one of the southernmost runs of chinook salmon in North America. Since 1980 numerous small glacial lakes formed behind the new terminal moraines of several of these glaciers. 'study of ice') is the scientific study of glaciers, or more generally ice and natural phenomena that involve ice. Satellite imagery indicates that these lakes are continuing to expand. Glaciology is an interdisciplinary Earth science that integrates geophysics, geology, physical geography, geomorphology, climatology, meteorology, hydrology, biology, and ecology. Much of the Merced River basin is at high elevation, where an alpine climate prevails. As a whole, the system includes about 4,000 control gates and 793 miles (1,276km) of canals and laterals. Three stages followed during the Wisconsinian glaciation; these were the Tahoe, Tenaya and Tioga stages, of which the Tioga was the smallest. Many Plains Miwok settled in the lowlands along the lower Merced River. A V shaped valley is formed due to the erosional work of a river. Environmental measures enacted in the late 20th century have had some success in boosting chinook salmon populations, from a record low of 500 fish during several years in the 1950s, to a high of 30,000 in 1984. When the ice under the till melts, the till slumps in and forms depressions called kettles. Other types of moraine include ground moraines (till-covered areas forming sheets on flat or irregular topography) and medial moraines (moraines formed where two glaciers meet). [38][39], Downstream of New Exchequer Dam is McSwain Dam, which serves as a regulating forebay for New Exchequer Dam and also generates power. Later, when the glaciers retreated leaving behind their freight of crushed rock and sand (glacial drift), they created characteristic depositional landforms.Examples include glacial moraines, eskers, and kames. Medial moraines are formed when two different glaciers merge and the lateral moraines of each coalesce to form a moraine in the middle of the combined glacier. Following the gold rush, the Ahwahnechee were allowed back into Yosemite Valley, but further incidents prompted a second battalion to drive them out, this time to the Mono Lake area. The meltwater at the snout of the glacier deposits its load of sediment over the outwash plain, with larger boulders being Glaciology is an interdisciplinary Earth science that integrates geophysics, geology, physical geography, geomorphology, climatology, meteorology, hydrology, biology, and ecology. Lake Constance was formed by the Rhine Glacier during the ice age and is a Zungenbecken or tongue lake. It is strongly characterised and divided into different areas by end moraines, various glacial snouts and medial moraines. The immense lateral moraine that was formed in the process is clearly visible from the moraine trail. Environmental movements led by John Muir and Robert Underwood Johnson convinced the U.S. Congress to establish Yosemite National Park in 1890. The Lake McClure gauge, located at the former mining town of Bagby, is probably the most accurate gauge for flows overall. It is strongly characterised and divided into different areas by end moraines, various glacial snouts and medial moraines. The Sierra receives heavy snowfall in the winter, which melts in the spring and early summer causing annual flooding. Conflicts between settlers and Native Americans resulted in wars, including the expulsion of the Ahwahnechee from Yosemite. Since 1980 numerous small glacial lakes formed behind the new terminal moraines of several of these glaciers. The old railroad grade still exists, and is now the site of a public trail. An outwash plain, also called a sandur (plural: sandurs), sandr or sandar, is a plain formed of glaciofluvial deposits due to meltwater outwash at the terminus of a glacier.As it flows, the glacier grinds the underlying rock surface and carries the debris along. When the ice under the till melts, the till slumps in and forms depressions called kettles. Around 11,000 years ago, the terminus of the glacier was in the Rhne Valley and the glacier's edge reached almost as far as Riederfurka. [27] Moraga's expedition was part of a series of exploratory ventures, funded by the Spanish government, to find suitable sites for missions in the Central Valley and the Sierra Nevada foothills. This modern structure was preceded by the old Exchequer Dam forming 281,000-acre-foot (347,000,000m3) Exchequer Reservoir. The work of the glacier then left an overdeepened U-shaped valley that ends abruptly at a valley or trough end. Those that fall on the sides of the glacier form lateral moraines. Several cities that did achieve prominence, however, include Merced and Turlock, both located on the railroad.[31]. The Sierra Miwok and Mono Lake Paiute eventually, through cultural interaction over time, formed a new culture, the Ahwahnechee, derived from Ahwahnee, meaning "the valley shaped like a big mouth" (referring to U-shaped Yosemite Valley). The California Gold Rush in the 1850s saw gradually increasing mining in Merced Canyon and Yosemite Valley. [17], When the North American Plate on its slow journey westwards encountered the Pacific Plate approximately 250 million years ago during the Paleozoic, the latter began to subduct under the North American continent. Irrigation return flows carry pesticides, fertilizer and other pollutants into the river. Efforts to mitigate environmental damage include habitat conservation work, re-establishment of historic streamflow patterns, and the construction of a salmon hatchery. The first roads were constructed into Yosemite Valley in the 1870s. The District proposed the Exchequer Dam, completed in the mid-1920s and raised in the 1960s, as a water storage facility on the Merced River. Drumlins and ribbed moraines are also landforms left behind by retreating glaciers. Beyond the glacial moraine at the western end of the valley the river flows through the steep Merced River Canyon, picks up Cascade Creek and turns south near El Portal. In 1991, a fish hatchery, the Merced River Hatchery, was built beside the Merced River just downstream of the Crocker-Huffman Diversion Dam, the lowermost Merced River dam. Glaciation during the ice ages carved the high elevation parts of the watershed, including Yosemite Valley, into their present shape. Before irrigation started in the Central Valley and dams were constructed, the river's natural flow at the mouth was much higher than the current average of 661 cubic feet per second (18.7m3/s), or about 479,000 acre-feet (591,000,000m3) per year. The subglacial environment is the one most difficult to observe. Another expedition to the Central Valley in 1805 also named the Kings River upon reaching it on January 6, 1805, which is the feast of the Magi or Epiphany. 'study of ice') is the scientific study of glaciers, or more generally ice and natural phenomena that involve ice. Other types of moraine include ground moraines (till-covered areas forming sheets on flat or irregular topography) and medial moraines (moraines formed where two glaciers meet). Yosemite Valley saw significant amounts of damage when the river flooded the valley in 1997. Glacier Bay Basin in southeastern Alaska, in the United States, encompasses the Glacier Bay and surrounding mountains and glaciers, which was first proclaimed a U.S. National Monument on February 25, 1925, and which was later, on December 2, 1980, enlarged and designated as the Glacier Bay National Park and Preserve under the Alaska National Interest Lands Conservation Large-scale irrigation was introduced to the San Joaquin Valley in the late 19th century, and led to the construction of numerous state, federal and privately owned dams, which blocked migrating salmon and caused a large decline in riparian habitat. gravity also carry sediments into the sea. The river then turns generally westward for another 3 miles (4.8km), where it snakes through a spectacular narrow gorge between massive, glacially resistant granite cliffs. This moraine was actually one of several moraines deposited by the four glaciations, which include Medial Moraine and Bridalveil Moraine. The river's character changes dramatically once it reaches the plains of the agricultural San Joaquin Valley, where it becomes a slow-moving meandering stream.[2]. This moraine was actually one of several moraines deposited by the four glaciations, which include Medial Moraine and Bridalveil Moraine. Glaciated landscapes are formed by a combination of erosion, transportation and deposition processes. Moraines are made up of pieces of rock that are shattered by frost action, embedded in the glaciers & brought down the valley. To the east, it is bordered by the Sierra crest which divides it from the endorheic Great Basin watershed of Mono Lake. It is most well known for its swift and steep course through the southern part of Yosemite National Park, where it is the primary watercourse flowing through Yosemite Valley. When lateral moraines adjacent to each other join, they create medial moraines, which are also carried down on the surface of the moving ice. Moraines are made up of pieces of rock that are shattered by frost action, embedded in the glaciers & brought down the valley. [44], The name "Railroad Flat" originates from the Yosemite Valley Railroad, which once travelled up Merced River Canyon into Yosemite Valley. [40] Below this dam is Merced Falls Dam, an irrigation diversion dam. The MID is federally required to allow at least 15,000 acre-feet (19,000,000m3) of water annually to flow continually down the river, not including floodwater releases. A true fjord is formed when a glacier cuts a U-shaped valley by ice segregation and abrasion of the surrounding bedrock. [6][7] The foothills experience a drier Mediterranean climate, while the San Joaquin Valley floor is dry enough to be considered semi-desert. We can also trace how the Great Aletsch Glacier has grown and receded in the landscape of the Aletsch Forest. Moraines. The average annual flow recorded there was 1,185 cubic feet per second (33.6m3/s) from 1923 to 1966. When two glaciers converge, their inside lateral moraines unite to form a medial moraine. Birds are more abundant along the slow-moving lower river, which has more suitable riparian habitat compared to the rocky, swift upper river. Upstream on the river, at Happy Isles, the average flow is 355 cubic feet per second (10.1m3/s). The California Gold Rush brought many people into California and some settled in towns along the lower Merced River. Many Native Americans in the area revolted, leading to conflicts between miners and the Ahwahnechee. Less apparent are ground moraines, also called glacial drift, which often blankets the surface underneath the glacier downslope from the equilibrium line. The lowermost, the Crocker-Huffman Diversion Dam, was built in 1906 and completely blocks the passage of anadromous fish up the Merced River. Password requirements: 6 to 30 characters long; ASCII characters only (characters found on a standard US keyboard); must contain at least 4 different symbols; Sediments formed in these different environments have different characteristics (particle size and sorting) because of their mode of deposition. By the late 1950s and early 1960s, irrigation in the San Joaquin Valley was to such an extent that many of the rivers ran dry in sections. When lateral moraines adjacent to each other join, they create medial moraines, which are also carried down on the surface of the moving ice. The Sugar Pine Lumber Company and Yosemite Lumber Company operated lumber mills at Merced Falls for over thirty years, relying on narrow-gauge railroads to ship lumber from the Sierra Nevada along the Merced River. Even before the establishment of Yosemite National Park, tourists began to travel into the Merced Canyon and Yosemite Valley as early as 1855. 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