Bay mud
Encyclopedia
Silt
Silt is granular material of a size somewhere between sand and clay whose mineral origin is quartz and feldspar. Silt may occur as a soil or as suspended sediment in a surface water body...
y clay
Clay
Clay is a general term including many combinations of one or more clay minerals with traces of metal oxides and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure.- Formation :Clay minerals...
, which is saturated with water
Water
Water is a chemical substance with the chemical formula H2O. A water molecule contains one oxygen and two hydrogen atoms connected by covalent bonds. Water is a liquid at ambient conditions, but it often co-exists on Earth with its solid state, ice, and gaseous state . Water also exists in a...
; these soil layers are situated at the bottom of certain estuaries
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
, which are normally in temperate regions that have experienced cyclical glacial cycles. Example locations are Cape Cod Bay
Cape Cod Bay
Cape Cod Bay is a large bay of the Atlantic Ocean adjacent to the U.S. state of Massachusetts. Measuring below a line drawn from Brant Rock in Marshfield to Race Point in Provincetown, Massachusetts, it is enclosed by Cape Cod to the south and east, and Plymouth County, Massachusetts, to the west....
, Chongming Dongtan Reserve in Shanghai
Shanghai
Shanghai is the largest city by population in China and the largest city proper in the world. It is one of the four province-level municipalities in the People's Republic of China, with a total population of over 23 million as of 2010...
, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
, Banc d'Arguinpreserve in Mauritania
Mauritania
Mauritania is a country in the Maghreb and West Africa. It is bordered by the Atlantic Ocean in the west, by Western Sahara in the north, by Algeria in the northeast, by Mali in the east and southeast, and by Senegal in the southwest...
, The Bristol Channel
Bristol Channel
The Bristol Channel is a major inlet in the island of Great Britain, separating South Wales from Devon and Somerset in South West England. It extends from the lower estuary of the River Severn to the North Atlantic Ocean...
in the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
, Mandø Island in the Wadden Sea
Wadden Sea
The Wadden Sea is an intertidal zone in the southeastern part of the North Sea. It lies between the coast of northwestern continental Europe and the range of Frisian Islands, forming a shallow body of water with tidal flats and wetlands. It is rich in biological diversity...
in Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
, Florida Bay
Florida Bay
Florida Bay is the bay located between the southern end of the Florida mainland and the Florida Keys. Its area is variously stated to be , or , or . Nearly all of Florida Bay is included in Everglades National Park. The southern edge, along the Florida Keys is in the Florida Keys National Marine...
, San Francisco Bay
San Francisco Bay
San Francisco Bay is a shallow, productive estuary through which water draining from approximately forty percent of California, flowing in the Sacramento and San Joaquin rivers from the Sierra Nevada mountains, enters the Pacific Ocean...
, Bay of Fundy
Bay of Fundy
The Bay of Fundy is a bay on the Atlantic coast of North America, on the northeast end of the Gulf of Maine between the Canadian provinces of New Brunswick and Nova Scotia, with a small portion touching the U.S. state of Maine...
, Casco Bay
Casco Bay
Casco Bay is an inlet of the Gulf of Maine on the southern coast of Maine, New England, United States. Its easternmost approach is Cape Small and its westernmost approach is Two Lights in Cape Elizabeth...
, Penobscot Bay
Penobscot Bay
Penobscot Bay originates from the mouth of Maine's Penobscot River. There are many islands in this bay, and on them, some of the country's most well-known summer colonies. The bay served as portal for the one time "lumber capital of the world," namely; the city of Bangor...
and Morro Bay. Bay mud manifests low shear strength
Shear strength (soil)
Shear strength is a term used in soil mechanics to describe the magnitude of the shear stress that a soil can sustain. The shear resistance of soil is a result of friction and interlocking of particles, and possibly cementation or bonding at particle contacts. Due to interlocking, particulate...
, high compressibility and low permeability
Permeability (fluid)
Permeability in fluid mechanics and the earth sciences is a measure of the ability of a porous material to allow fluids to pass through it.- Units :...
, making it hazardous to build upon in seismically active regions like the San Francisco Bay Area
San Francisco Bay Area
The San Francisco Bay Area, commonly known as the Bay Area, is a populated region that surrounds the San Francisco and San Pablo estuaries in Northern California. The region encompasses metropolitan areas of San Francisco, Oakland, and San Jose, along with smaller urban and rural areas...
.
Typical bulk density of bay mud is approximately 1.3 grams per cubic centimeter. Bay muds often have a high organic
Organic matter
Organic matter is matter that has come from a once-living organism; is capable of decay, or the product of decay; or is composed of organic compounds...
content, consisting of decayed organisms at lower depths, but may also contain living creatures when they occur at the upper soil layer and become exposed by low tides; then, they are called mudflat
Mudflat
Mudflats or mud flats, also known as tidal flats, are coastal wetlands that form when mud is deposited by tides or rivers. They are found in sheltered areas such as bays, bayous, lagoons, and estuaries. Mudflats may be viewed geologically as exposed layers of bay mud, resulting from deposition of...
s, an important ecological zone for shorebirds and many types of marine organisms. Great attention was not given to the incidence of deeper bay muds until the 1960s and 1970s when development encroachment on certain North American bays intensified, requiring geotechnical design of foundations.
Bay mud has its own official geological abbreviation. The designation for Quaternary
Quaternary
The Quaternary Period is the most recent of the three periods of the Cenozoic Era in the geologic time scale of the ICS. It follows the Neogene Period, spanning 2.588 ± 0.005 million years ago to the present...
older bay mud is Qobm and the acronym for Quaternary younger bay mud is Qybm. An alluvial layer is often found overlying the older bay mud.
In relation to shipping channels, it is often necessary to dredge bay bottoms and barge the excavated material to an alternate location. In this case chemical analyses are usually performed on the bay mud to determine whether there are elevated levels of heavy metals, PCB
Polychlorinated biphenyl
Polychlorinated biphenyls are a class of organic compounds with 2 to 10 chlorine atoms attached to biphenyl, which is a molecule composed of two benzene rings. The chemical formula for PCBs is C12H10-xClx...
s or other toxic substances known to accumulate in a benthic environment. It is not uncommon to dredge the same channel
Channel (geography)
In physical geography, a channel is the physical confine of a river, slough or ocean strait consisting of a bed and banks.A channel is also the natural or human-made deeper course through a reef, sand bar, bay, or any shallow body of water...
repeatedly (over a span of ten to thirty years) since further settling sediments are prone to redeposit on an open estuarine valley floor.
Depositional scenarios
Detritus
Detritus is a biological term used to describe dead or waste organic material.Detritus may also refer to:* Detritus , a geological term used to describe the particles of rock produced by weathering...
(e.g. decomposition of estuarine diatom
Diatom
Diatoms are a major group of algae, and are one of the most common types of phytoplankton. Most diatoms are unicellular, although they can exist as colonies in the shape of filaments or ribbons , fans , zigzags , or stellate colonies . Diatoms are producers within the food chain...
s) may form a separate distinct layer. Thus bay muds are important time records of glacial activity and streamflow throughout the Quaternary
Quaternary
The Quaternary Period is the most recent of the three periods of the Cenozoic Era in the geologic time scale of the ICS. It follows the Neogene Period, spanning 2.588 ± 0.005 million years ago to the present...
period.
Some depositional formation is quite recent, such as in the case of Florida Bay, where much of the bay mud has accumulated since 2000 BC, and consists of primarily decayed organic material In the case of Florida Bay these bay muds can accrete as much as 0.5 to 2.0 centimeters per annum, although the dynamic equilibrium of erosion
Erosion
Erosion is when materials are removed from the surface and changed into something else. It only works by hydraulic actions and transport of solids in the natural environment, and leads to the deposition of these materials elsewhere...
, wave action redistribution and deposition complicate the net rate of layer growth. In the case of the Bristol Channel
Bristol Channel
The Bristol Channel is a major inlet in the island of Great Britain, separating South Wales from Devon and Somerset in South West England. It extends from the lower estuary of the River Severn to the North Atlantic Ocean...
in the United Kingdom bay mud formation has been occurring at least since the Eemian Stage (known as the Sangamonian Stage
Sangamonian Stage
The Sangamonian Stage, also known as the Sangamon interglacial, is the name used by Quaternary geologists to designate the last interglacial period in North America from 125,000—75,000 years ago, a period of...
in North America
North America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, or about 130,000 years ago. In other cases such as with San Francisco Bay
San Francisco Bay
San Francisco Bay is a shallow, productive estuary through which water draining from approximately forty percent of California, flowing in the Sacramento and San Joaquin rivers from the Sierra Nevada mountains, enters the Pacific Ocean...
, deposition has been interrupted by sea-level changes, and strata of vastly different vintages are found. In the San Francisco Bay Area, these are called Young bay mud and Older bay mud by geologist
Geologist
A geologist is a scientist who studies the solid and liquid matter that constitutes the Earth as well as the processes and history that has shaped it. Geologists usually engage in studying geology. Geologists, studying more of an applied science than a theoretical one, must approach Geology using...
s. Human activities can also affect deposition; close to half of the Young Bay Mud in San Francisco Bay was placed in the period 1855-1865, as a result of placer mining
Placer mining
Placer mining is the mining of alluvial deposits for minerals. This may be done by open-pit or by various surface excavating equipment or tunneling equipment....
in the Sierra Nevada foothills.
Geotechnical factors
A number of notable buildings have been constructed over bay muds, typically employing special mitigation designs to withstand seismic risks and settlement issues. Complicating design issues, fill (beginning about 1850 AD) is sometimes found deposited on the surface level. For example, the Dakin Building
Dakin Building
The Dakin Building is an architectural award-winning class A office building on the San Francisco Bay in Brisbane, California. Serving as a corporate headquarters building for several companies of national prominence, it was built from the profits of the Garfield character whose licensed products...
in Brisbane, California
Brisbane, California
Brisbane is a small city located in the northern part of San Mateo County, California on the lower slopes of San Bruno Mountain. It is on the northeastern edge of South San Francisco, next to the San Francisco Bay and near the San Francisco International Airport.The population was 4,282 as of...
was designed in 1985 to sit on piles 150 feet deep, anchoring to the Franciscan formation, below the bay muds and through an upper fill layer. Furthermore the structure’s entrance ramp has been set on a giant hinge to allow the surrounding land to settle, while the building absolute height remains constant. The Crowne Plaza high-rise hotel
Hotel
A hotel is an establishment that provides paid lodging on a short-term basis. The provision of basic accommodation, in times past, consisting only of a room with a bed, a cupboard, a small table and a washstand has largely been replaced by rooms with modern facilities, including en-suite bathrooms...
in Burlingame, California
Burlingame, California
Burlingame is a city in San Mateo County, California. It is located on the San Francisco Peninsula and has a significant shoreline on San Francisco Bay. The city is named after diplomat Anson Burlingame. It is renowned for its many surviving examples of Victorian architecture, its affluence, and...
was also designed to sit over bay muds, as was the Westin Hotel in Millbrae, California
Millbrae, California
Millbrae is a city in San Mateo County, California, United States, just west of San Francisco Bay, with San Bruno on the north and Burlingame on the south. The population was 21,532 at the 2010 census.-History:...
and Trinity Church in Boston's Copley Square. Indeed, Boston's entire Back Bay district is named for the tidal bay that it now covers. Logan International Airport
Logan International Airport
General Edward Lawrence Logan International Airport is located in the East Boston neighborhood of Boston, Massachusetts . It covers , has six runways, and employs an estimated 16,000 people. It is the 19th busiest airport in the United States.Boston serves as a focus city for JetBlue Airways...
and the San Francisco International Airport
San Francisco International Airport
San Francisco International Airport is a major international airport located south of downtown San Francisco, California, United States, near the cities of Millbrae and San Bruno in unincorporated San Mateo County. It is often referred to as SFO...
are also constructed over bay mud.
Mudflats
When the mud layer is exposed at the tidal fringe, mudflats result affording a unique ecotoneEcotone
An ecotone is a transition area between two biomes but different patches of the landscape, such as forest and grassland. It may be narrow or wide, and it may be local or regional...
that affords numerous shorebird species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...
a safe feeding and resting habitat. Because the muds function much like quicksand
Quicksand
Quicksand is a colloid hydrogel consisting of fine granular matter , clay, and water.Water circulation underground can focus in an area with the optimal mixture of fine sands and other materials such as clay. The water moves up and then down slowly in a convection-like manner throughout a column...
, heavier mammal
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
ian predators not only cannot gain traction for pursuit, but would actually become trapped in the sinking muds. The muds are also an important substrate for primary marsh
Marsh
In geography, a marsh, or morass, is a type of wetland that is subject to frequent or continuous flood. Typically the water is shallow and features grasses, rushes, reeds, typhas, sedges, other herbaceous plants, and moss....
productivity including eelgrass
Zostera
Zostera is a small genus of widely distributed seagrass, commonly called marine eelgrass or simply eelgrass . The genus Zostera contains sixteen species.-Ecology:Zostera is found on sandy substrates or in estuaries submerged or partially floating...
, cordgrass
Cordgrass
Spartina, commonly known as cordgrass or cord-grass, is a genus of 14 species of grasses in the family Poaceae. They are native to the coasts of the Atlantic Ocean in western and southern Europe, northwest and southern Africa, the Americas and the southern Atlantic Ocean islands; one or two species...
and pickleweed
Pickleweed
Pickleweed is a common name used for two unrelated genera of flowering plants:*Batis, family Bataceae*Salicornia, family Amaranthaceae...
. Furthermore they are home to a large variety of molluscs and estuarine arthropod
Arthropod
An arthropod is an invertebrate animal having an exoskeleton , a segmented body, and jointed appendages. Arthropods are members of the phylum Arthropoda , and include the insects, arachnids, crustaceans, and others...
s. Richardson Bay, for example, exposes one third of its areal extent as mudflat at low tide, which hosts a productive eelgrass expanse and also a large shorebird community.
Mammals such as the Harbor seal
Harbor Seal
The harbor seal , also known as the common seal, is a true seal found along temperate and Arctic marine coastlines of the Northern Hemisphere...
may use mudflats to haul out of estuary waters; however, larger mammals such as humpback whale
Humpback Whale
The humpback whale is a species of baleen whale. One of the larger rorqual species, adults range in length from and weigh approximately . The humpback has a distinctive body shape, with unusually long pectoral fins and a knobbly head. It is an acrobatic animal, often breaching and slapping the...
s may become accidentally stranded at low tides. Note that normally humpback whales do not frequent estuaries containing mudflats, but at least one errant whale, publicized by the media as Humphrey the humpback whale
Humphrey the Whale
Humphrey the Whale is arguably the most widely publicized humpback whale in history, having errantly entered San Francisco Bay twice, departing from his Mexico to Alaska migration. This behavior is not normal for any Humpback whale, and Humphrey became well known on national television and press...
, became stuck on a mudflat in San Francisco Bay at Sierra Point in Brisbane, California.
Worldwide occurrences
Bay muds occur in bays and estuaries throughout the temperate regions of the world. In North AmericaNorth America
North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...
, prominent instances are: (a) the Stellwagen Bank formed 16,000 to 9000 BC by glaciation of Cape Cod Bay
Cape Cod Bay
Cape Cod Bay is a large bay of the Atlantic Ocean adjacent to the U.S. state of Massachusetts. Measuring below a line drawn from Brant Rock in Marshfield to Race Point in Provincetown, Massachusetts, it is enclosed by Cape Cod to the south and east, and Plymouth County, Massachusetts, to the west....
in Massachusetts
Massachusetts
The Commonwealth of Massachusetts is a state in the New England region of the northeastern United States of America. It is bordered by Rhode Island and Connecticut to the south, New York to the west, and Vermont and New Hampshire to the north; at its east lies the Atlantic Ocean. As of the 2010...
, (b) Florida Bay,(c) in California Morro Bay and San Francisco Bay and (d) Knik & Turnagain Arms in Anchorage, Alaska. In the United Kingdom
United Kingdom
The United Kingdom of Great Britain and Northern IrelandIn the United Kingdom and Dependencies, other languages have been officially recognised as legitimate autochthonous languages under the European Charter for Regional or Minority Languages...
large bay mud occurrences are found at Morecambe Bay
Morecambe Bay
Morecambe Bay is a large bay in northwest England, nearly due east of the Isle of Man and just to the south of the Lake District National Park. It is the largest expanse of intertidal mudflats and sand in the United Kingdom, covering a total area of 310 km².-Natural features:The rivers Leven,...
, Bridgwater Bay
Bridgwater Bay
Bridgwater Bay is on the Bristol Channel, north of Bridgwater in Somerset, England at the mouth of the River Parrett and the end of the River Parrett Trail. It consists of large areas of mud flats, saltmarsh, sandflats and shingle ridges, some of which are vegetated...
and Bristol Bay. Straddling Denmark
Denmark
Denmark is a Scandinavian country in Northern Europe. The countries of Denmark and Greenland, as well as the Faroe Islands, constitute the Kingdom of Denmark . It is the southernmost of the Nordic countries, southwest of Sweden and south of Norway, and bordered to the south by Germany. Denmark...
, the Netherlands
Netherlands
The Netherlands is a constituent country of the Kingdom of the Netherlands, located mainly in North-West Europe and with several islands in the Caribbean. Mainland Netherlands borders the North Sea to the north and west, Belgium to the south, and Germany to the east, and shares maritime borders...
and Germany
Germany
Germany , officially the Federal Republic of Germany , is a federal parliamentary republic in Europe. The country consists of 16 states while the capital and largest city is Berlin. Germany covers an area of 357,021 km2 and has a largely temperate seasonal climate...
is the Wadden Sea
Wadden Sea
The Wadden Sea is an intertidal zone in the southeastern part of the North Sea. It lies between the coast of northwestern continental Europe and the range of Frisian Islands, forming a shallow body of water with tidal flats and wetlands. It is rich in biological diversity...
, a major formation underlain by bay muds.
In Asia the Chongming Dongtan Nature Reserve in Shanghai
Shanghai
Shanghai is the largest city by population in China and the largest city proper in the world. It is one of the four province-level municipalities in the People's Republic of China, with a total population of over 23 million as of 2010...
, China
China
Chinese civilization may refer to:* China for more general discussion of the country.* Chinese culture* Greater China, the transnational community of ethnic Chinese.* History of China* Sinosphere, the area historically affected by Chinese culture...
is an example of a large scale bay mud formation. The Atlantic coast
Atlantic Ocean
The Atlantic Ocean is the second-largest of the world's oceanic divisions. With a total area of about , it covers approximately 20% of the Earth's surface and about 26% of its water surface area...
of Africa
Africa
Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...
holds the Banc d'Arguin, a World Heritage nature preserve in the country of Mauritania
Mauritania
Mauritania is a country in the Maghreb and West Africa. It is bordered by the Atlantic Ocean in the west, by Western Sahara in the north, by Algeria in the northeast, by Mali in the east and southeast, and by Senegal in the southwest...
. Banc d'Arguin is a vast area underlain by bay mud.
Regulatory issues
When building on top of bay mud layers or when dredging estuary bottoms, a variety of regulatory frameworks may arise. Normally in the United States, an Environmental Impact Report as well as a geotechnical investigation are conducted precedent to any major construction over bay mud. Combined, these reports have developed much of the data base extant on bay mud characteristics, frequently yielding original field data from soil borings. These data have demonstrated that in many locations the shallower bay muds contain concentrations of mercuryMercury (element)
Mercury is a chemical element with the symbol Hg and atomic number 80. It is also known as quicksilver or hydrargyrum...
, lead
Lead
Lead is a main-group element in the carbon group with the symbol Pb and atomic number 82. Lead is a soft, malleable poor metal. It is also counted as one of the heavy metals. Metallic lead has a bluish-white color after being freshly cut, but it soon tarnishes to a dull grayish color when exposed...
, chromium
Chromium
Chromium is a chemical element which has the symbol Cr and atomic number 24. It is the first element in Group 6. It is a steely-gray, lustrous, hard metal that takes a high polish and has a high melting point. It is also odorless, tasteless, and malleable...
, petroleum hydrocarbon
Hydrocarbon
In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons from which one hydrogen atom has been removed are functional groups, called hydrocarbyls....
s, PCBs, pesticide
Pesticide
Pesticides are substances or mixture of substances intended for preventing, destroying, repelling or mitigating any pest.A pesticide may be a chemical unicycle, biological agent , antimicrobial, disinfectant or device used against any pest...
s and other chemicals which exceed toxic limits: a geological record of human activities of the last century. These data are particularly important to consider when dredging of bay muds is contemplated as part of a development project. Such dredging can have impacts to receiving lands as soil contamination
Soil contamination
Soil contamination or soil pollution is caused by the presence of xenobiotic chemicals or other alteration in the natural soil environment....
, but also water column impacts from sediment disturbance.
In the case of dredging within the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, a permit is almost always required from the United States Army Corps of Engineers
United States Army Corps of Engineers
The United States Army Corps of Engineers is a federal agency and a major Army command made up of some 38,000 civilian and military personnel, making it the world's largest public engineering, design and construction management agency...
, after submittal of extensive data on the project limits, chemical properties of the bay muds to be disturbed, a dredge disposal plan and often a complete Environmental Impact Statement
Environmental impact statement
An environmental impact statement , under United States environmental law, is a document required by the National Environmental Policy Act for certain actions "significantly affecting the quality of the human environment". An EIS is a tool for decision making...
pursuant to the National Environmental Policy Act
National Environmental Policy Act
The National Environmental Policy Act is a United States environmental law that established a U.S. national policy promoting the enhancement of the environment and also established the President's Council on Environmental Quality ....
. Further review by the United States Coast Guard
United States Coast Guard
The United States Coast Guard is a branch of the United States Armed Forces and one of the seven U.S. uniformed services. The Coast Guard is a maritime, military, multi-mission service unique among the military branches for having a maritime law enforcement mission and a federal regulatory agency...
would normally be required. Within individual state jurisdictions, such as California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
, an Environmental Impact Report must be filed for dredging of any significance; furthermore, agency reviews by the California Coastal Commission
California Coastal Commission
The California Coastal Commission is a state agency in the U.S. state of California with quasi-judicial regulatory oversight over land use and public access in the California coastal zone....
and the Regional Water Quality Control Board would normally be mandated. .
For buildings proposed over bay mud layers, typically the municipality involved will, in addition to the usual engineering and design review issues common to all building projects (which are more complicated because of the site conditions), require an Environmental Impact Report http://ceres.ca.gov/topic/env_law/ceqa/guidelines/. This process would include reviews by that city’s building department, as well as applicable regional and state agencies such as those cited above for dredging projects, except that Coast Guard agencies would not typically be concerned.
See also
- EstuaryEstuaryAn estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....
- GlacierGlacierA glacier is a large persistent body of ice that forms where the accumulation of snow exceeds its ablation over many years, often centuries. At least 0.1 km² in area and 50 m thick, but often much larger, a glacier slowly deforms and flows due to stresses induced by its weight...
- LiquefactionLiquefactionLiquefaction may refer to:* Liquefaction, the general process of becoming liquid* Soil liquefaction, the process by which sediments become suspended* Liquefaction of gases in physics, chemistry, and thermal engineering* Liquefactive necrosis in pathology...
- United States Army Corps of EngineersUnited States Army Corps of EngineersThe United States Army Corps of Engineers is a federal agency and a major Army command made up of some 38,000 civilian and military personnel, making it the world's largest public engineering, design and construction management agency...