An ice dune, also called an ice ridge or an ice foot, is a formation of ice that accumulates on the shores of many arctic beaches and is also common along the shores of the Great Lakes during the winter. [1] Ice dunes are not to be confused with ice shoves, which accumulate on bodies of water then push their way on shore, carrying sediment with them and deforming the shoreline.
An ice dune is produced by ice washing ashore, snowfall, and the gradual freezing of wave spray that accumulates on to the shore. [2] They form when the air temperature is below freezing and the water temperature is near freezing. [2] Ice dunes are commonly at least six feet (1.8 m) tall, but the dune's size depends on the beach and the weather. [2] The tidal range, the storminess of the water and the topography of the beach all can affect the size of the dunes. [3] The dunes will also stop forming if the body of the water they border freezes over, which often happens on Lake Erie. [2] Ice dunes will usually break up in the early stages of spring thaw.
Ice dunes are important in formations, such as sandspits and sand isthmuses, that could be eroded by wave action. An example of a Great Lakes sandspit is Presque Isle State Park in Erie, Pennsylvania. [2] When the dunes form, they form a barrier between the waves and the shore and prevent the waves from reaching the shore, keeping the sand in place.
Because of the way ice dunes form, they are inherently weak and filled with cracks and air pockets. People who venture out onto the dunes sometimes will fall through. If the dune extends out over the water, persons who do this can fall through the dune and into the freezing water underneath; if this happens, hypothermia and death by drowning are urgent, immediate dangers. [2]
A dune is a landform composed of wind- or water-driven sand. It typically takes the form of a mound, ridge, or hill. An area with dunes is called a dune system or a dune complex. A large dune complex is called a dune field, while broad, flat regions covered with wind-swept sand or dunes with little or no vegetation are called ergs or sand seas. Dunes occur in different shapes and sizes, but most kinds of dunes are longer on the stoss (upflow) side, where the sand is pushed up the dune, and have a shorter slip face in the lee side. The valley or trough between dunes is called a dune slack.
Ice is water frozen into a solid state, typically forming at or below temperatures of 0 degrees Celsius or 32 degrees Fahrenheit. Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaque bluish-white color.
Lake Erie is the fourth largest lake of the five Great Lakes in North America and the eleventh-largest globally. It is the southernmost, shallowest, and smallest by volume of the Great Lakes and therefore also has the shortest average water residence time. At its deepest point Lake Erie is 210 feet (64 m) deep.
Lake Michigan is one of the five Great Lakes of North America. It is the second-largest of the Great Lakes by volume and the third-largest by surface area, after Lake Superior and Lake Huron. To the east, its basin is conjoined with that of Lake Huron through the narrow Straits of Mackinac, giving it the same surface elevation as its easterly counterpart; the two are technically a single lake.
Point Pelee National Park is a national park in Essex County in southwestern Ontario, Canada where it extends into Lake Erie. The word pelée is French for 'bald'. Point Pelee consists of a peninsula of land, mainly of marsh and woodland habitats, that tapers to a sharp point as it extends into Lake Erie. Middle Island, also part of Point Pelee National Park, was acquired in 2000 and is just north of the Canada–United States border in Lake Erie. Point Pelee is the southernmost point of mainland Canada, and is located on a foundation of glacial sand, silt and gravel that bites into Lake Erie. This spit of land is slightly more than seven kilometres long by 4.5 kilometres (2.8 mi) wide at its northern base. Established in 1918, Point Pelee was the first national park in Canada to be established for conservation. It was designated as a Ramsar site on 27 May 1987.
Long Point is a sand spit and medium-sized hamlet on the north shore of Lake Erie, part of Norfolk County in the province of Ontario, Canada.
In oceanography, geomorphology, and geoscience, a shoal is a natural submerged ridge, bank, or bar that consists of, or is covered by, sand or other unconsolidated material and rises from the bed of a body of water to near the surface. It often refers to those submerged ridges, banks, or bars that rise near enough to the surface of a body of water as to constitute a danger to navigation. Shoals are also known as sandbanks, sandbars, or gravelbars. Two or more shoals that are either separated by shared troughs or interconnected by past or present sedimentary and hydrographic processes are referred to as a shoal complex.
A spit or sandspit is a deposition bar or beach landform off coasts or lake shores. It develops in places where re-entrance occurs, such as at a cove's headlands, by the process of longshore drift by longshore currents. The drift occurs due to waves meeting the beach at an oblique angle, moving sediment down the beach in a zigzag pattern. This is complemented by longshore currents, which further transport sediment through the water alongside the beach. These currents are caused by the same waves that cause the drift.
Frazil ice is a collection of loose, randomly oriented ice crystals millimeter and sub-millimeter in size, with various shapes, e.g. elliptical disks, dendrites, needles and of an irregular nature. Frazil ice forms during the winter in open-water reaches of rivers as well as in lakes and reservoirs, where and when the water is in a turbulent state, which is, in turn, induced by the action of waves and currents. Turbulence causes the water column to become supercooled, as the heat exchange between the air and the water is such that the water temperature drops below its freezing point. The vertical mixing associated with that turbulence provides enough energy to overcome the crystals' buoyancy, thus keeping them from floating at the surface. Frazil ice also forms in oceans, where windy conditions, wave regimes and cold air also favor the establishment of a supercooled layer. Frazil ice can be found on the downwind side of leads, and in polynyas. In these environments, that ice can eventually accumulate at the water surface into what is referred to as grease ice.
An ice volcano is a conical mound of ice formed over a terrestrial lake via the eruption of water and slush through an ice shelf. The process is wave-driven, with wind providing the energy for the waves to cut through the ice and create formations that loosely mimic the shape and activity of volcanoes. After being ejected into the atmosphere, the liquid water and slush freeze and fall back to the surface, growing the formation. Ice may also be erupted. The phenomenon is most often observed along the southern coast of Lake Erie and Lake Ontario, when the temperature is below freezing and the wind blows onshore with a velocity of at least 25 mph (40 km/h). They are known to reduce coastal erosion there. The formations are temporary: they are frequently destroyed by storms and warm weather, and once the lake wholly freezes over, eruptions are no longer possible.
Coastal geography is the study of the constantly changing region between the ocean and the land, incorporating both the physical geography and the human geography of the coast. It includes understanding coastal weathering processes, particularly wave action, sediment movement and weather, and the ways in which humans interact with the coast
Presque Isle State Park is a 3,112-acre (1,259 ha) Pennsylvania State Park on an arching, sandy peninsula that juts into Lake Erie, 4 miles (6 km) west of the city of Erie, in Millcreek Township, Erie County, Pennsylvania, in the United States. The peninsula sweeps northeastward, surrounding Presque Isle Bay along the park's southern coast. It has 13 miles (21 km) of roads, 21 miles (34 km) of recreational trails, 13 beaches for swimming, and a marina. Popular activities at the park include swimming, boating, hiking, biking, and birdwatching.
An ice shove is a surge of ice from an ocean or large lake onto the shore. Ice shoves are caused by ocean currents, strong winds, or temperature differences pushing ice onto the shore, creating piles up to 12 metres high. Ice shoves can be caused by temperature fluctuations, wind action, or changing water levels and can cause devastation to coastal Arctic communities. Climate change will also play a role in the formation and frequency of ice shove events; a rise in global temperatures leads to more open water to facilitate ice movement and low pressure systems to destabilize ice sheets and send them shoreward.
Anchor ice is defined by the World Meteorological Organization as "submerged ice attached or anchored to the bottom, irrespective of the nature of its formation". It may also be called bottom-fast ice. Anchor ice is most commonly observed in fast-flowing rivers during periods of extreme cold, at the mouths of rivers flowing into very cold seawater, in the shallow sub or intertidal during or after storms when the air temperature is below the freezing point of the water, and the subtidal in the Antarctic along ice shelves or near floating glacier tongues, and in shallow lakes.
Lake Chicago was a prehistoric proglacial lake that is the ancestor of what is now known as Lake Michigan, one of North America's five Great Lakes. Fed by retreating glaciers, it drained south through the Chicago Outlet River.
A beach ridge is a wave-swept or wave-deposited ridge running parallel to a shoreline. It is commonly composed of sand as well as sediment worked from underlying beach material. The movement of sediment by wave action is called littoral transport. Movement of material parallel to the shoreline is called longshore transport. Movement perpendicular to the shore is called on-offshore transport. A beach ridge may be capped by, or associated with, sand dunes. The height of a beach ridge is affected by wave size and energy.
Shelf ice is ice that forms when a portion of a lake surface freezes. It is often then washed upon the shore. The phenomenon is common within the Great Lakes.
Beach evolution occurs at the shoreline where sea, lake or river water is eroding the land. Beaches exist where sand accumulated from centuries-old, recurrent processes that erode rocky and sedimentary material into sand deposits. River deltas deposit silt from upriver, accreting at the river's outlet to extend lake or ocean shorelines. Catastrophic events such as tsunamis, hurricanes, and storm surges accelerate beach erosion.
A surf break is a permanent obstruction such as a coral reef, rock, shoal, or headland that causes a wave to break, forming a barreling wave or other wave that can be surfed, before it eventually collapses. The topography of the seabed determines the shape of the wave and type of break. Since shoals can change size and location, affecting the break, it takes commitment and skill to find good breaks. Some surf breaks are quite dangerous, since the surfer can collide with a reef or rocks below the water.
Ice lenses are bodies of ice formed when moisture, diffused within soil or rock, accumulates in a localized zone. The ice initially accumulates within small collocated pores or pre-existing crack, and, as long as the conditions remain favorable, continues to collect in the ice layer or ice lens, wedging the soil or rock apart. Ice lenses grow parallel to the surface and several centimeters to several decimeters deep in the soil or rock. Studies from 1990 have demonstrated that rock fracture by ice segregation is a more effective weathering process than the freeze-thaw process which older texts proposed.
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