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84-705: Salhusfjorden is a 4-kilometer (2.5 mi) long fjord and sound between Bergen Municipality and Alver Municipality in Vestland county, Norway . To the west, it starts between the villages of Salhus and Frekhaug , where the Byfjorden meets the Herdlefjorden . To the east, the fjord ends between the village of Knarvik and the Hordvikneset peninsula, where the Osterfjorden runs northeast,

168-602: A Germanic noun for a travel : North Germanic ferd or färd and of the verb to travel , Dutch varen , German fahren ; English to fare . As a loanword from Norwegian, it is one of the few words in the English language to start with the sequence fj . The word was for a long time normally spelled f i ord , a spelling preserved in place names such as Grise Fiord . The fiord spelling mostly remains only in New Zealand English , as in

252-424: A certain proportion of its mass below the surface of the water. If snow falls to the top of the iceberg, the iceberg will sink lower in the water. If a layer of ice melts off the top of the iceberg, the remaining iceberg will rise. Similarly, Earth's lithosphere "floats" in the asthenosphere. When continents collide, the continental crust may thicken at their edges in the collision. It is also very common for one of

336-425: A change in crust loading) provide information on the viscosity of the upper mantle. The basis of the model is Pascal's law , and particularly its consequence that, within a fluid in static equilibrium, the hydrostatic pressure is the same on every point at the same elevation (surface of hydrostatic compensation): h 1 ⋅ρ 1 = h 2 ⋅ρ 2 = h 3 ⋅ρ 3 = ... h n ⋅ρ n For the simplified picture shown,

420-535: A characteristic wave number As the rigid layer becomes weaker, κ {\displaystyle \kappa } approaches infinity, and the behavior approaches the pure hydrostatic balance of the Airy-Heiskanen hypothesis. The depth of compensation (also known as the compensation level , compensation depth , or level of compensation ) is the depth below which the pressure is identical across any horizontal surface. In stable regions, it lies in

504-628: A common Germanic origin of the word. The landscape consists mainly of moraine heaps. The Föhrden and some "fjords" on the east side of Jutland, Denmark are also of glacial origin. But while the glaciers digging "real" fjords moved from the mountains to the sea, in Denmark and Germany they were tongues of a huge glacier covering the basin of which is now the Baltic Sea. See Förden and East Jutland Fjorde . Whereas fjord names mostly describe bays (though not always geological fjords), straits in

588-451: A fjord as a kind of sea ( Māori : tai ) that runs by a bluff ( matapari , altogether tai matapari "bluff sea"). The term "fjord" is sometimes applied to steep-sided inlets which were not created by glaciers. Most such inlets are drowned river canyons or rias . Examples include: Some Norwegian freshwater lakes that have formed in long glacially carved valleys with sill thresholds, ice front deltas or terminal moraines blocking

672-456: A glacial river flows in. Velfjorden has little inflow of freshwater. In 2000, some coral reefs were discovered along the bottoms of the Norwegian fjords. These reefs were found in fjords from the north of Norway to the south. The marine life on the reefs is believed to be one of the most important reasons why the Norwegian coastline is such a generous fishing ground. Since this discovery

756-421: A highly productive group of phytoplankton that enable such fjords to be valuable feeding grounds for other species. It is possible that as climate change reduces long-term meltwater output, nutrient dynamics within such fjords will shift to favor less productive species, destabilizing the food web ecology of fjord systems. In addition to nutrient flux, sediment carried by flowing glaciers can become suspended in

840-533: A local hydrostatic balance. A third hypothesis, lithospheric flexure , takes into account the rigidity of the Earth's outer shell, the lithosphere . Lithospheric flexure was first invoked in the late 19th century to explain the shorelines uplifted in Scandinavia following the melting of continental glaciers at the end of the last glaciation . It was likewise used by American geologist G. K. Gilbert to explain

924-529: A long, narrow inlet. In eastern Norway, the term is also applied to long narrow freshwater lakes ( Randsfjorden and Tyrifjorden ) and sometimes even to rivers (for instance in Flå Municipality in Hallingdal , the Hallingdal river is referred to as fjorden ). In southeast Sweden, the name fjard fjärd is a subdivision of the term 'fjord' used for bays, bights and narrow inlets on

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1008-544: A narrower sound is called sund . In the Finnish language , a word vuono is used although there is only one fjord in Finland. In old Norse genitive was fjarðar whereas dative was firði . The dative form has become common place names like Førde (for instance Førde ), Fyrde or Førre (for instance Førre ). The German use of the word Föhrde for long narrow bays on their Baltic Sea coastline, indicates

1092-500: A protected passage almost the entire 1,601 km (995 mi) route from Stavanger to North Cape , Norway. The Blindleia is a skerry-protected waterway that starts near Kristiansand in southern Norway and continues past Lillesand . The Swedish coast along Bohuslän is likewise skerry guarded. The Inside Passage provides a similar route from Seattle , Washington , and Vancouver , British Columbia , to Skagway , Alaska . Yet another such skerry-protected passage extends from

1176-490: A region, the land may rise to compensate. Therefore, as a mountain range is eroded, the (reduced) range rebounds upwards (to a certain extent) to be eroded further. Some of the rock strata now visible at the ground surface may have spent much of their history at great depths below the surface buried under other strata, to be eventually exposed as those other strata eroded away and the lower layers rebounded upwards. An analogy may be made with an iceberg , which always floats with

1260-675: A suffix in names of some Scandinavian fjords and has in same cases also been transferred to adjacent settlements or surrounding areas for instance Hardanger , Stavanger , and Geiranger . The differences in usage between the English and the Scandinavian languages have contributed to confusion in the use of the term fjord. Bodies of water that are clearly fjords in Scandinavian languages are not considered fjords in English; similarly bodies of water that would clearly not be fjords in

1344-653: Is 160 m (520 ft) deep with a threshold of only 1.5 m (4 ft 11 in), while the 1,300 m (4,300 ft) deep Sognefjorden has a threshold around 100 to 200 m (330 to 660 ft) deep. Hardangerfjord is made up of several basins separated by thresholds: The deepest basin Samlafjorden between Jonaneset ( Jondal ) and Ålvik with a distinct threshold at Vikingneset in Kvam Municipality . Hanging valleys are common along glaciated fjords and U-shaped valleys . A hanging valley

1428-582: Is 2,000 m (6,562 ft) below the surrounding regional topography. Fjord lakes are common on the inland lea of the Coast Mountains and Cascade Range ; notable ones include Lake Chelan , Seton Lake , Chilko Lake , and Atlin Lake . Kootenay Lake , Slocan Lake and others in the basin of the Columbia River are also fjord-like in nature, and created by glaciation in the same way. Along

1512-483: Is a tributary valley that is higher than the main valley and was created by tributary glacier flows into a glacier of larger volume. The shallower valley appears to be 'hanging' above the main valley or a fjord. Often, waterfalls form at or near the outlet of the upper valley. Small waterfalls within these fjords are also used as freshwater resources. Hanging valleys also occur underwater in fjord systems. The branches of Sognefjord are for instance much shallower than

1596-454: Is a long, narrow sea inlet with steep sides or cliffs, created by a glacier . Fjords exist on the coasts of Antarctica , the Arctic , and surrounding landmasses of the northern and southern hemispheres. Norway's coastline is estimated to be 29,000 km (18,000 mi) long with its nearly 1,200 fjords, but only 2,500 km (1,600 mi) long excluding the fjords . A true fjord

1680-414: Is accompanied by the rebounding of Earth's crust as the ice load and eroded sediment is removed (also called isostasy or glacial rebound). In some cases, this rebound is faster than sea level rise . Most fjords are deeper than the adjacent sea ; Sognefjord , Norway , reaches as much as 1,300 m (4,265 ft) below sea level . Fjords generally have a sill or shoal (bedrock) at their mouth caused by

1764-412: Is also often described as a fjord, but is actually a freshwater lake cut off from the sea, so is not a fjord in the English sense of the term. Locally they refer to it as a "landlocked fjord". Such lakes are sometimes called "fjord lakes". Okanagan Lake was the first North American lake to be so described, in 1962. The bedrock there has been eroded up to 650 m (2,133 ft) below sea level, which

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1848-430: Is at least 500 m (1,600 ft) deep and water takes an average of 16 years to flow through the lake. Such lakes created by glacial action are also called fjord lakes or moraine-dammed lakes . Some of these lakes were salt after the ice age but later cut off from the ocean during the post-glacial rebound . At the end of the ice age Eastern Norway was about 200 m (660 ft) lower (the marine limit). When

1932-456: Is borrowed from Norwegian , where it is pronounced [ˈfjuːr] , [ˈfjøːr] , [ˈfjuːɽ] or [ˈfjøːɽ] in various dialects and has a more general meaning, referring in many cases to any long, narrow body of water, inlet or channel (for example, see Oslofjord ). The Norwegian word is inherited from Old Norse fjǫrðr , a noun which refers to a 'lake-like' body of water used for passage and ferrying and

2016-620: Is closely related to the noun ferð "travelling, ferrying, journey". Both words go back to Indo-European *pértus "crossing", from the root *per- "cross". The words fare and ferry are of the same origin. The Scandinavian fjord , Proto-Scandinavian * ferþuz , is the origin for similar Germanic words: Icelandic fjörður , Faroese fjørður , Swedish fjärd (for Baltic waterbodies), Scots firth (for marine waterbodies, mainly in Scotland and northern England). The Norse noun fjǫrðr

2100-463: Is cut almost in two by the Svelvik "ridge", a sandy moraine that was below sea level when it was covered by ice, but after the post-glacial rebound reaches 60 m (200 ft) above the fjord. In the 19th century, Jens Esmark introduced the theory that fjords are or have been created by glaciers and that large parts of Northern Europe had been covered by thick ice in prehistory. Thresholds at

2184-528: Is defined as the Bouger anomaly minus the gravity anomaly due to the subsurface compensation, and is a measure of the local departure from isostatic equilibrium. At the center of a level plateau, it is approximately equal to the free air anomaly . Models such as deep dynamic isostasy (DDI) include such viscous forces and are applicable to a dynamic mantle and lithosphere. Measurements of the rate of isostatic rebound (the return to isostatic equilibrium following

2268-653: Is fairly new, little research has been done. The reefs are host to thousands of lifeforms such as plankton , coral , anemones , fish, several species of shark, and many more. Most are specially adapted to life under the greater pressure of the water column above it, and the total darkness of the deep sea. New Zealand's fjords are also host to deep-water corals , but a surface layer of dark fresh water allows these corals to grow in much shallower water than usual. An underwater observatory in Milford Sound allows tourists to view them without diving. In some places near

2352-458: Is formed when a glacier cuts a U-shaped valley by ice segregation and abrasion of the surrounding bedrock. According to the standard model, glaciers formed in pre-glacial valleys with a gently sloping valley floor. The work of the glacier then left an overdeepened U-shaped valley that ends abruptly at a valley or trough end. Such valleys are fjords when flooded by the ocean. Thresholds above sea level create freshwater lakes. Glacial melting

2436-505: Is located on the southern shore of Lake Superior in Michigan . The principal mountainous regions where fjords have formed are in the higher middle latitudes and the high latitudes reaching to 80°N (Svalbard, Greenland), where, during the glacial period, many valley glaciers descended to the then-lower sea level. The fjords develop best in mountain ranges against which the prevailing westerly marine winds are orographically lifted over

2520-445: Is the acceleration due to gravity, and P ( x ) {\displaystyle P(x)} is the load on the ocean crust. The parameter D is the flexural rigidity , defined as where E is Young's modulus , σ {\displaystyle \sigma } is Poisson's ratio , and T c {\displaystyle T_{c}} is the thickness of the lithosphere. Solutions to this equation have

2604-470: Is the freshwater fjord Movatnet (Mo lake) that until 1743 was separated from Romarheimsfjorden by an isthmus and connected by a short river. During a flood in November 1743, the river bed eroded and sea water could flow into the lake at high tide. Eventually, Movatnet became a saltwater fjord and renamed Mofjorden ( Mofjorden ). Like fjords, freshwater lakes are often deep. For instance Hornindalsvatnet

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2688-409: Is the isthmus with a village between Hornindalsvatnet lake and Nordfjord . Such lakes are also denoted fjord valley lakes by geologists. One of Norway's largest is Tyrifjorden at 63 m (207 ft) above sea level and an average depth at 97 m (318 ft) most of the lake is under sea level. Norway's largest lake, Mjøsa , is also referred to as "the fjord" by locals. Another example

2772-410: Is usually a large inflow of river water in the inner areas. This freshwater gets mixed with saltwater creating a layer of brackish water with a slightly higher surface than the ocean which in turn sets up a current from the river mouths towards the ocean. This current is gradually more salty towards the coast and right under the surface current there is a reverse current of saltier water from the coast. In

2856-476: The Baltic Sea and Hudson Bay . As the ice retreats, the load on the lithosphere and asthenosphere is reduced and they rebound back towards their equilibrium levels. In this way, it is possible to find former sea cliffs and associated wave-cut platforms hundreds of metres above present-day sea level . The rebound movements are so slow that the uplift caused by the ending of the last glacial period

2940-636: The British Columbia Coast , a notable fjord-lake is Owikeno Lake , which is a freshwater extension of Rivers Inlet . Quesnel Lake , located in central British Columbia, is claimed to be the deepest fjord formed lake on Earth. A family of freshwater fjords are the embayments of the North American Great Lakes. Baie Fine is located on the northwestern coast of Georgian Bay of Lake Huron in Ontario , and Huron Bay

3024-459: The Scandinavian sense of the term, are not universally considered to be fjords by the scientific community, because although glacially formed, most Finnmark fjords lack the steep-sided valleys of the more southerly Norwegian fjords. The glacial pack was deep enough to cover even the high grounds when they were formed. The Oslofjord , on the other hand, is a rift valley , and not glacially formed. The indigenous Māori people of New Zealand see

3108-613: The Straits of Magellan north for 800 km (500 mi). Fjords provide unique environmental conditions for phytoplankton communities. In polar fjords, glacier and ice sheet outflow add cold, fresh meltwater along with transported sediment into the body of water. Nutrients provided by this outflow can significantly enhance phytoplankton growth. For example, in some fjords of the West Antarctic Peninsula (WAP), nutrient enrichment from meltwater drives diatom blooms,

3192-645: The Sørfjorden runs southeast, and the Radfjorden runs north. The fjord is up to 500 meters (1,600 ft) deep. It acts as one of the borders between the districts of Midhordland to the south and Nordhordland to the north. The islands of Holsnøy and Flatøy lie along the northern side of the fjord. Salhusfjorden is crossed by the Nordhordland Bridge , a 1,614-meter (5,295 ft) combined pontoon and cable stayed bridge . Because of

3276-543: The Viking settlers—though the inlet at that place in modern terms is an estuary , not a fjord. Similarly the name of Milford (now Milford Haven) in Wales is derived from Melrfjǫrðr ("sandbank fjord/inlet"), though the inlet on which it is located is actually a ria. Before or in the early phase of Old Norse angr was another common noun for fjords and other inlets of the ocean. This word has survived only as

3360-856: The Limfjord once was a fjord until the sea broke through from the west. Ringkøbing Fjord on the western coast of Jutland is a lagoon . The long narrow fjords of Denmark's Baltic Sea coast like the German Förden were dug by ice moving from the sea upon land, while fjords in the geological sense were dug by ice moving from the mountains down to the sea. However, some definitions of a fjord is: "A long narrow inlet consisting of only one inlet created by glacial activity". Examples of Danish fjords are: Kolding Fjord , Vejle Fjord and Mariager Fjord . The fjords in Finnmark in Norway, which are fjords in

3444-560: The Pratt hypothesis as overlying regions of unusually low density in the upper mantle. This reflects thermal expansion from the higher temperatures present under the ridges. In the Basin and Range Province of western North America, the isostatic anomaly is small except near the Pacific coast, indicating that the region is generally near isostatic equilibrium. However, the depth to the base of

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3528-546: The Scandinavian sense have been named or suggested to be fjords. Examples of this confused usage follow. In the Danish language some inlets are called a fjord, but are, according to the English language definition, technically not a fjord, such as Roskilde Fjord . Limfjord in English terminology is a sound , since it separates the North Jutlandic Island (Vendsyssel-Thy) from the rest of Jutland . However,

3612-476: The Swedish Baltic Sea coast, and in most Swedish lakes. This latter term is also used for bodies of water off the coast of Finland where Finland Swedish is spoken. In Danish, the word may even apply to shallow lagoons . In modern Icelandic, fjörður is still used with the broader meaning of firth or inlet. In Faroese fjørður is used both about inlets and about broader sounds, whereas

3696-403: The balancing of lithospheric columns gives: where ρ m {\displaystyle \rho _{m}} is the density of the mantle (ca. 3,300 kg m ), ρ c {\displaystyle \rho _{c}} is the density of the crust (ca. 2,750 kg m ) and ρ w {\displaystyle \rho _{w}} is the density of

3780-520: The bedrock. This may in particular have been the case in Western Norway where the tertiary uplift of the landmass amplified eroding forces of rivers. Confluence of tributary fjords led to excavation of the deepest fjord basins. Near the very coast, the typical West Norwegian glacier spread out (presumably through sounds and low valleys) and lost their concentration and reduced the glaciers' power to erode leaving bedrock thresholds. Bolstadfjorden

3864-524: The case of Hardangerfjord the fractures of the Caledonian fold has guided the erosion by glaciers, while there is no clear relation between the direction of Sognefjord and the fold pattern. This relationship between fractures and direction of fjords is also observed in Lyngen . Preglacial, tertiary rivers presumably eroded the surface and created valleys that later guided the glacial flow and erosion of

3948-403: The country before the bridge opened in 1994. At first operated by Fergetrafikk , from 1967 it was run by Bergen Nordhordland Rutelag . Until 1984, there was also a ferry crossing between Salhus and Frekhaug, operated by the same company. Fjord In physical geography , a fjord (also spelled fiord in New Zealand English ; ( / ˈ f j ɔːr d , f iː ˈ ɔːr d / )

4032-418: The crust does not strongly correlate with the height of the terrain. This provides evidence (via the Pratt hypothesis) that the upper mantle in this region is inhomogeneous, with significant lateral variations in density. The formation of ice sheets can cause Earth's surface to sink. Conversely, isostatic post-glacial rebound is observed in areas once covered by ice sheets that have now melted, such as around

4116-448: The deep crust, but in active regions, it may lie below the base of the lithosphere. In the Pratt model, it is the depth below which all rock has the same density; above this depth, density is lower where topographic elevation is greater. When large amounts of sediment are deposited on a particular region, the immense weight of the new sediment may cause the crust below to sink. Similarly, when large amounts of material are eroded away from

4200-434: The deeper parts of the fjord the cold water remaining from winter is still and separated from the atmosphere by the brackish top layer. This deep water is ventilated by mixing with the upper layer causing it to warm and freshen over the summer. In fjords with a shallow threshold or low levels of mixing this deep water is not replaced every year and low oxygen concentration makes the deep water unsuitable for fish and animals. In

4284-406: The deformation of the rigid crust. These elastic forces can transmit buoyant forces across a large region of deformation to a more concentrated load. Perfect isostatic equilibrium is possible only if mantle material is in rest. However, thermal convection is present in the mantle. This introduces viscous forces that are not accounted for the static theory of isostacy. The isostatic anomaly or IA

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4368-411: The depth of the mountain belt roots (b 1 ) is calculated as follows: where ρ m {\displaystyle \rho _{m}} is the density of the mantle (ca. 3,300 kg m ) and ρ c {\displaystyle \rho _{c}} is the density of the crust (ca. 2,750 kg m ). Thus, generally: In the case of negative topography (a marine basin),

4452-487: The depth, the bridge lacks lateral anchorage. The bridge, which carries European Route E39 , was opened on 22 September 1994. It is the second-longest bridge in Norway. The fjord takes its name from the village area of Salhus , which during the Viking Age in the early 12th century there was an inn (known at the time as a sáluhus ), which would give name to the place. It acted as a transport hub for Nordhordland, and

4536-413: The fjord. Bolstadfjorden has a threshold of only 1.5 m (4 ft 11 in) and strong inflow of freshwater from Vosso river creates a brackish surface that blocks circulation of the deep fjord. The deeper, salt layers of Bolstadfjorden are deprived of oxygen and the seabed is covered with organic material. The shallow threshold also creates a strong tidal current. During the summer season, there

4620-403: The flexural rigidity of the lithosphere approaches zero. For example, the vertical displacement z of a region of ocean crust would be described by the differential equation where ρ m {\displaystyle \rho _{m}} and ρ w {\displaystyle \rho _{w}} are the densities of the aesthenosphere and ocean water, g

4704-489: The formation of sea ice. The study of phytoplankton communities within fjords is an active area of research, supported by groups such as FjordPhyto, a citizen science initiative to study phytoplankton samples collected by local residents, tourists, and boaters of all backgrounds. An epishelf lake forms when meltwater is trapped behind a floating ice shelf and the freshwater floats on the denser saltwater below. Its surface may freeze forming an isolated ecosystem. The word fjord

4788-500: The gravitational attraction of the nearby Andes Mountains . However, the deflection was less than expected, which was attributed to the mountains having low-density roots that compensated for the mass of the mountains. In other words, the low-density mountain roots provided the buoyancy to support the weight of the mountains above the surrounding terrain. Similar observations in the 19th century by British surveyors in India showed that this

4872-477: The ice cap receded and allowed the ocean to fill valleys and lowlands, and lakes like Mjøsa and Tyrifjorden were part of the ocean while Drammen valley was a narrow fjord. At the time of the Vikings Drammensfjord was still four or five m (13 or 16 ft) higher than today and reached the town of Hokksund , while parts of what is now the city of Drammen was under water. After the ice age

4956-446: The level of the original sea level. In Eidfjord, Eio has dug through the original delta and left a 110 m (360 ft) terrace while lake is only 19 m (62 ft) above sea level. Such deposits are valuable sources of high-quality building materials (sand and gravel) for houses and infrastructure. Eidfjord village sits on the eid or isthmus between Eidfjordvatnet lake and Eidfjorden branch of Hardangerfjord. Nordfjordeid

5040-471: The main fjord. The mouth of Fjærlandsfjord is about 400 m (1,300 ft) deep while the main fjord is 1,200 m (3,900 ft) nearby. The mouth of Ikjefjord is only 50 m (160 ft) deep while the main fjord is around 1,300 m (4,300 ft) at the same point. During the winter season, there is usually little inflow of freshwater. Surface water and deeper water (down to 100 m or 330 ft or more) are mixed during winter because of

5124-497: The marine limit. Like freshwater fjords, the continuation of fjords on land are in the same way denoted as fjord-valleys . For instance Flåmsdal ( Flåm valley) and Måbødalen . Outside of Norway, the three western arms of New Zealand 's Lake Te Anau are named North Fiord, Middle Fiord and South Fiord. Another freshwater "fjord" in a larger lake is Western Brook Pond , in Newfoundland's Gros Morne National Park ; it

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5208-405: The most extreme cases, there is a constant barrier of freshwater on the surface and the fjord freezes over such that there is no oxygen below the surface. Drammensfjorden is one example. The mixing in fjords predominantly results from the propagation of an internal tide from the entrance sill or internal seiching. The Gaupnefjorden branch of Sognefjorden is strongly affected by freshwater as

5292-569: The mountainous regions, resulting in abundant snowfall to feed the glaciers. Hence coasts having the most pronounced fjords include the west coast of Norway, the west coast of North America from Puget Sound to Alaska, the southwest coast of New Zealand, and the west and to south-western coasts of South America , chiefly in Chile . Other regions have fjords, but many of these are less pronounced due to more limited exposure to westerly winds and less pronounced relief. Areas include: The longest fjords in

5376-462: The mouths and overdeepening of fjords compared to the ocean are the strongest evidence of glacial origin, and these thresholds are mostly rocky. Thresholds are related to sounds and low land where the ice could spread out and therefore have less erosive force. John Walter Gregory argued that fjords are of tectonic origin and that glaciers had a negligible role in their formation. Gregory's views were rejected by subsequent research and publications. In

5460-448: The ocean was about 150 m (490 ft) at Notodden . The ocean stretched like a fjord through Heddalsvatnet all the way to Hjartdal . Post-glacial rebound eventually separated Heddalsvatnet from the ocean and turned it into a freshwater lake. In neolithic times Heddalsvatnet was still a saltwater fjord connected to the ocean, and was cut off from the ocean around 1500 BC. Some freshwater fjords such as Slidrefjord are above

5544-423: The outlet follow the Norwegian naming convention; they are frequently named fjords. Ice front deltas developed when the ice front was relatively stable for long time during the melting of the ice shield. The resulting landform is an isthmus between the lake and the saltwater fjord, in Norwegian called "eid" as in placename Eidfjord or Nordfjordeid . The post-glacial rebound changed these deltas into terraces up to

5628-439: The outlet of fjords where submerged glacially formed valleys perpendicular to the coast join with other cross valleys in a complex array. The island fringe of Norway is such a group of skerries (called a skjærgård ); many of the cross fjords are so arranged that they parallel the coast and provide a protected channel behind an almost unbroken succession of mountainous islands and skerries. By this channel, one can travel through

5712-465: The place name Fiordland . The use of the word fjord in Norwegian, Danish and Swedish is more general than in English and in international scientific terminology. In Scandinavia, fjord is used for a narrow inlet of the sea in Norway, Denmark and western Sweden, but this is not its only application. In Norway and Iceland, the usage is closest to the Old Norse, with fjord used for both a firth and for

5796-478: The plates to be underthrust beneath the other plate. The result is that the crust in the collision zone becomes as much as 80 kilometers (50 mi) thick, versus 40 kilometers (25 mi) for average continental crust. As noted above , the Airy hypothesis predicts that the resulting mountain roots will be about five times deeper than the height of the mountains, or 32 km versus 8 km. In other words, most of

5880-452: The previous glacier's reduced erosion rate and terminal moraine . In many cases this sill causes extreme currents and large saltwater rapids (see skookumchuck ). Saltstraumen in Norway is often described as the world's strongest tidal current . These characteristics distinguish fjords from rias (such as the Bay of Kotor ), which are drowned valleys flooded by the rising sea. Drammensfjorden

5964-641: The same regions typically are named Sund , in Scandinavian languages as well as in German. The word is related to "to sunder" in the meaning of "to separate". So the use of Sound to name fjords in North America and New Zealand differs from the European meaning of that word. The name of Wexford in Ireland is originally derived from Veisafjǫrðr ("inlet of the mud flats") in Old Norse, as used by

6048-487: The seaward margins of areas with fjords, the ice-scoured channels are so numerous and varied in direction that the rocky coast is divided into thousands of island blocks, some large and mountainous while others are merely rocky points or rock reefs , menacing navigation. These are called skerries . The term skerry is derived from the Old Norse sker , which means a rock in the sea. Skerries most commonly formed at

6132-419: The steady cooling of the surface and wind. In the deep fjords, there is still fresh water from the summer with less density than the saltier water along the coast. Offshore wind, common in the fjord areas during winter, sets up a current on the surface from the inner to the outer parts. This current on the surface in turn pulls dense salt water from the coast across the fjord threshold and into the deepest parts of

6216-434: The thickened crust moves downwards rather than up, just as most of an iceberg is below the surface of the water. However, convergent plate margins are tectonically highly active, and their surface features are partially supported by dynamic horizontal stresses, so that they are not in complete isostatic equilibrium. These regions show the highest isostatic anomalies on the Earth's surface. Mid-ocean ridges are explained by

6300-408: The thickness of the crust. This hypothesis was suggested to explain how large topographic loads such as seamounts (e.g. Hawaiian Islands ) could be compensated by regional rather than local displacement of the lithosphere. This is the more general solution for lithospheric flexure , as it approaches the locally compensated models above as the load becomes much larger than a flexural wavelength or

6384-560: The uplifted shorelines of Lake Bonneville . The concept was further developed in the 1950s by the Dutch geodesist Vening Meinesz . Three principal models of isostasy are used: Airy and Pratt isostasy are statements of buoyancy, but flexural isostasy is a statement of buoyancy when deflecting a sheet of finite elastic strength. In other words, the Airy and Pratt models are purely hydrostatic, taking no account of material strength, while flexural isostacy takes into account elastic forces from

6468-401: The water (ca. 1,000 kg m ). Thus, generally: For the simplified model shown the new density is given by: ρ 1 = ρ c c h 1 + c {\displaystyle \rho _{1}=\rho _{c}{\frac {c}{h_{1}+c}}} , where h 1 {\displaystyle h_{1}} is the height of the mountain and c

6552-455: The water column, increasing turbidity and reducing light penetration into greater depths of the fjord. This effect can limit the available light for photosynthesis in deeper areas of the water mass, reducing phytoplankton abundance beneath the surface. Overall, phytoplankton abundance and species composition within fjords is highly seasonal, varying as a result of seasonal light availability and water properties that depend on glacial melt and

6636-587: The word 'isostasy' in 1889 to describe this general phenomenon. However, two hypotheses to explain the phenomenon had by then already been proposed, in 1855, one by George Airy and the other by John Henry Pratt . The Airy hypothesis was later refined by the Finnish geodesist Veikko Aleksanteri Heiskanen and the Pratt hypothesis by the American geodesist John Fillmore Hayford . Both the Airy-Heiskanen and Pratt-Hayford hypotheses assume that isostacy reflects

6720-477: The world are: Deep fjords include: Isostasy Although Earth is a dynamic system that responds to loads in many different ways, isostasy describes the important limiting case in which crust and mantle are in static equilibrium . Certain areas (such as the Himalayas and other convergent margins) are not in isostatic equilibrium and are not well described by isostatic models. The general term isostasy

6804-529: Was a small market town. It was one of the first industrialized places when a hosiery manufacturer was established here in 1859. Previously, there were two ferry crossings of the Salhusfjorden. Starting on 7 July 1936, a ferry service ran between the villages of Isdalstø and Steinestø . In 1956, the ferry on the Nordhordland side moved to Knarvik , and it was the most trafficked ferry service in

6888-503: Was a widespread phenomenon in mountainous areas. It was later found that the difference between the measured local gravitational field and what was expected for the altitude and local terrain (the Bouguer anomaly ) is positive over ocean basins and negative over high continental areas. This shows that the low elevation of ocean basins and high elevation of continents is also compensated at depth. The American geologist Clarence Dutton use

6972-589: Was adopted in German as Förde , used for the narrow long bays of Schleswig-Holstein , and in English as firth "fjord, river mouth". The English word ford (compare German Furt , Low German Ford or Vörde , in Dutch names voorde such as Vilvoorde, Ancient Greek πόρος , poros , and Latin portus ) is assumed to originate from Germanic * ferþu- and Indo-European root * pertu- meaning "crossing point". Fjord/firth/Förde as well as ford/Furt/Vörde/voorde refer to

7056-486: Was coined in 1882 by the American geologist Clarence Dutton . In the 17th and 18th centuries, French geodesists (for example, Jean Picard ) attempted to determine the shape of the Earth (the geoid ) by measuring the length of a degree of latitude at different latitudes ( arc measurement ). A party working in Ecuador was aware that its plumb lines , used to determine the vertical direction, would be deflected by

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