In other words, it is concerned with those geological factors that influence the location, design, construction and maintenance of engineering works. 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 depositional landforms of glacial are described in below: A) Moraines (Fig 1): Ridges or layers of till are called moraines, they are of four types: i) ground moraines, ii) lateral moraines, iii) medial moraines, and iv) terminal moraines. As noted in the Preface to the first edition, engineering geology can be defined as the application of Geology to engineering practice. The Merced continues to the northwest for 3 miles (4.8km) where collects into Merced Lake. There is also boating on Lake McClure. Over millions of years, the Merced cut a deep canyon through the softer sedimentary rock, eventually hitting the hard granite beneath. [33] Many place names in the valley have their origin from the Mariposa Battalion. Many of these birds are migratory and only pass the area a few times every year, while 109 species of birds are found only in the breeding season. There are no trails along some segments, including the lower Bridalveil Creek, upper South Fork, and specifically Tenaya Canyon, which is extremely dangerous.[6]. [40] Below this dam is Merced Falls Dam, an irrigation diversion dam. The Yosemite Valley Railroad, originally established with the discovery of mineral deposits in Yosemite Valley and Merced Canyon, continued functioning through the early 20th century carrying tourists to Yosemite Valley along the Merced River. The Sierra receives heavy snowfall in the winter, which melts in the spring and early summer causing annual flooding. Many Native Americans in the area revolted, leading to conflicts between miners and the Ahwahnechee. Campgrounds along the Merced River and its tributaries include ones at Railroad Flat, McCabe Flat, Willow Placer, Merced Lake, Vogelsang Lake, Sunrise Creek, May Lake, Bridalveil Creek, and a ski hut at Ostrander Lake, the source of Bridalveil Creek. The subglacial environment is the one most difficult to observe. [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. Up to 85% of the flow above Happy Isles comes from melting snow. The Merced River watershed encompasses 1,726 square miles (4,470km2) in the central Sierra Nevada. To the east, it is bordered by the Sierra crest which divides it from the endorheic Great Basin watershed of Mono Lake. [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. Moraines. [23] After the Tioga Glacier retreated this moraine formed a lake that flooded nearly the entire valley. 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. moraines and erratics. 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. Depending ond the location of the deposits, moraines can be divided into 4 types: ground moraines, lateral moraines, medial moraines and terminal 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. When lateral moraines adjacent to each other join, they create medial moraines, which are also carried down on the surface of the moving ice. To the north it is bordered by the watershed of the Tuolumne River, the other major river draining Yosemite National Park. [44], The name "Railroad Flat" originates from the Yosemite Valley Railroad, which once travelled up Merced River Canyon into Yosemite Valley. The most difficult rapids in this segment rate Class III and Class IV, mostly upstream of El Portal. We can also trace how the Great Aletsch Glacier has grown and receded in the landscape of the Aletsch Forest. Lake Constance was formed by the Rhine Glacier during the ice age and is a Zungenbecken or tongue lake. Birds that occur commonly in the middle and upper sections of the Merced River include mourning dove, Cassin's finch, California quail, dark-eyed junco, woodpecker, dipper, great blue heron, scrub jay, red-winged blackbird, red-tailed hawk, turkey vulture, cliff swallow, canyon wren, merganser, and bald eagles. Less apparent are ground moraines, also called glacial drift, which often blankets the surface underneath the glacier downslope from the equilibrium line. Moraines are made up of pieces of rock that are shattered by frost action, embedded in the glaciers & brought down the valley. 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. Common species of bird throughout the basin include ruby-crowned kinglet, cedar waxwing, American robin, yellow-rumped warbler, tree swallow and European starling, and several endangered species, including white-tailed kite and Swainson's hawk. Glaciology (from Latin glacies 'frost, ice', and Ancient Greek () 'subject matter'; lit. Since the 1970s, the annual chinook run has averaged about 5,300. Password requirements: 6 to 30 characters long; ASCII characters only (characters found on a standard US keyboard); must contain at least 4 different symbols; 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. In the mid-20th century, the flow in the Merced River diminished to such a degree that very few salmon returned to spawn in the lower section of the Merced River. It joins the San Joaquin River at Hills Ferry, a few miles south of Turlock.[4][5][6]. A true fjord is formed when a glacier cuts a U-shaped valley by ice segregation and abrasion of the surrounding bedrock. When the ice under the till melts, the till slumps in and forms depressions called kettles. The course of the Merced then turns to the north west and flows through a steep walled canyon for 2.5 miles (4.0km) where the river receives the Red Peak Fork and then collects into Washburn Lake, 7,612 feet (2,320m) above sea level. National Hydrography Dataset high-resolution flowline data. The California Gold Rush brought many people into California and some settled in towns along the lower Merced River. 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 After the Tioga Glacier retreated this moraine formed a lake that flooded nearly the entire valley. This moraine was actually one of several moraines deposited by the four glaciations, which include Medial Moraine and Bridalveil Moraine. When two glaciers converge, their inside lateral moraines unite to form a medial moraine. [11] For the mouth gauge, the highest flow was only 13,600 cubic feet per second (390m3/s) in 1950. 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. [20][21], When the last glacial period or Ice Age arrived, a series of four tremendous valley glaciers filled the upper basin of the Merced River. The meltwater at the snout of the glacier deposits its load of sediment over the outwash plain, with larger boulders being It is strongly characterised and divided into different areas by end moraines, various glacial snouts and medial moraines. Glaciology (from Latin glacies 'frost, ice', and Ancient Greek () 'subject matter'; lit. Whitewater rafting is permitted throughout Merced River Canyon from the downstream half of Yosemite Valley to the entrance of Lake McClure. The first was Coulterville Road, followed by Big Oak Flat Road, a trading route from Stockton to Merced Canyon. One of these trips, headed by lieutenant Gabriel Moraga, arrived on the south bank of the Merced River on September 29, 1806. 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. Moraines. The California Gold Rush in the 1850s saw gradually increasing mining in Merced Canyon and Yosemite Valley. Glaciology is an interdisciplinary Earth science that integrates geophysics, geology, physical geography, geomorphology, climatology, meteorology, hydrology, biology, and ecology. The salamander depends on the limestone walls of the Merced Canyon to survive. "Air Temperature and Snowmelt Discharge Characteristics, Merced River at Happy Isles, Yosemite National Park, Central Sierra Nevada", "USGS Gage #11268500 on the Merced River at Bagby, CA (Monthly Statistics)", "USGS Gage #11268500 on the Merced River at Bagby, CA: Peak Streamflow", "Fish, Water Insects and Birds along the Merced River", "A Boating Trail Guide to the Wild and Scenic Merced River (Page 2)", "Limestone Salamander Area of Critical Environmental Concern", "A Brief Story of the Geology of Yosemite Valley", "Geologic guide to the Merced Canyon and Yosemite Valley, California: with road logs from Hayward through Yosemite Valley, via Tracy, Patterson, Turlock and Merced Falls", "Scientific Investigations Report 20075216", "Merced River has a vital role: Re-licensing of Merced Irrigation District's dams could have far-reaching consequences", San Joaquin Salmon in creek running north, https://en.wikipedia.org/w/index.php?title=Merced_River&oldid=1118952948, Rivers of the Sierra Nevada (United States), Wild and Scenic Rivers of the United States, Rivers of the Sierra Nevada in California, Short description is different from Wikidata, Creative Commons Attribution-ShareAlike License 3.0, Confluence of Merced Peak and Triple Peak Forks. 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. [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. New Exchequer Dam is the largest dam on the river and forms Lake McClure, which holds 1,032,000 acre-feet (1.273109m3) of water for irrigation, flood control and hydropower generation. 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. Lateral moraines are those formed at the side of the ice flow, and terminal moraines were formed at the foot, marking the maximum advance of the glacier. A railroad was built along the Merced canyon, enabling mining and logging in the upper watershed, and later carrying tourists to Yosemite National Park. These various areas of the lake have their own names. In the dry season, groundwater provides the only base flow to the river. [14] Historically, the range of anadromous fish extended to the waterfalls at the head of Yosemite Valley, but dams have blocked their migration since the early 1900s, and diversions frequently dewater their remaining spawning habitat in the lower part of the river. 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 These various areas of the lake have their own names. Yosemite Valley saw significant amounts of damage when the river flooded the valley in 1997. Those that fall on the sides of the glacier form lateral moraines. In 1855, Merced County was created, named after the Merced River. [42][43], The Merced River and its tributaries are a popular recreational area in part because of Yosemite National Park. Password requirements: 6 to 30 characters long; ASCII characters only (characters found on a standard US keyboard); must contain at least 4 different symbols; In the late 1880s a flour mill, woolen mill and a few lumber mills were constructed at Merced Falls. The Merced River (/mrsd/), in the central part of the U.S. state of California, is a 145-mile (233km)-long[1] tributary of the San Joaquin River flowing from the Sierra Nevada into the San Joaquin Valley. [28], Following the establishment of Merced County and the independence of California from Mexico, many settlers came to the Merced River area and established small towns on the Merced River. Since 1980 numerous small glacial lakes formed behind the new terminal moraines of several of these glaciers. The river arcs northwest to receive the North Fork, and a few miles after it enters Lake McClure, formed by New Exchequer Dam. The old railroad grade still exists, and is now the site of a public trail. Sediments formed in these different environments have different characteristics (particle size and sorting) because of their mode of deposition. Birds are more abundant along the slow-moving lower river, which has more suitable riparian habitat compared to the rocky, swift upper river. Irrigation has taken most of the water out of the lower river, which is often reduced to a small stream where it joins the San Joaquin.
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