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An ice dune, also called an ice ridge or an ice foot, is a formation of
An ice dune, also called an ice ridge or an ice foot, is a formation of ice
Ice is water frozen into a solid state, typically forming at or below temperatures of 0 degrees Celsius or Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaq ...
that accumulates on the shores of many arctic
The Arctic ( or ) is a polar regions of Earth, polar region located at the northernmost part of Earth. The Arctic consists of the Arctic Ocean, adjacent seas, and parts of Canada (Yukon, Northwest Territories, Nunavut), Danish Realm (Greenla ...
beaches and is also common along the shores of the Great Lakes
The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lakes ...
during the winter
Winter is the coldest season of the year in polar and temperate climates. It occurs after autumn and before spring. The tilt of Earth's axis causes seasons; winter occurs when a hemisphere is oriented away from the Sun. Different cultures ...
.French 2007, p. 273. 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.
Cause
An ice dune is produced by ice washing ashore, snowfall, and the gradual freezing of wave spray that accumulates on to the shore. They form when the air temperature is below freezing and the water temperature is near freezing. Ice dunes are commonly at least tall, but the dune's size depends on the beach and the weather. Thetidal range
Tidal range is the difference in height between high tide and low tide. Tides are the rise and fall of sea levels caused by gravitational forces exerted by the Moon and Sun and the rotation of Earth. Tidal range depends on time and location.
...
, the ''storminess'' of the water and the topography of the beach all can affect the size of the dunes.French 2007 p. 276. The dunes will also stop forming if the body of the water they border freezes over, which often happens on Lake Erie
Lake Erie ( "eerie") is the fourth largest lake by surface area 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 t ...
. Ice dunes will usually break up in the early stages of spring thaw.
Effects
Ice dunes are important in formations, such as sandspits and sandisthmus
An isthmus (; ; ) is a narrow piece of land connecting two larger areas across an expanse of water by which they are otherwise separated. A tombolo is an isthmus that consists of a spit or bar, and a strait is the sea counterpart of an isthmu ...
es, that could be eroded
Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust, and then sediment transport, tra ...
by wave action. An example of a Great Lakes sandspit is Presque Isle State Park
Presque Isle State Park () is a Pennsylvania State Park on an arching, sandy peninsula that juts into Lake Erie, west of the city of Erie, in Millcreek Township, Erie County, Pennsylvania, in the United States. The peninsula sweeps northe ...
in Erie, Pennsylvania
Erie (; ) is a city on the south shore of Lake Erie and the county seat of Erie County, Pennsylvania, United States. Erie is the fifth largest city in Pennsylvania and the largest city in Northwestern Pennsylvania with a population of 94,831 a ...
. 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
Hypothermia is defined as a body core temperature below in humans. Symptoms depend on the temperature. In mild hypothermia, there is shivering and mental confusion. In moderate hypothermia, shivering stops and confusion increases. In severe h ...
and death by drown
Drowning is a type of suffocation induced by the submersion of the mouth and nose in a liquid. Most instances of fatal drowning occur alone or in situations where others present are either unaware of the victim's situation or unable to offer as ...
ing are urgent, immediate dangers.
See also
*Ice shove
An ice shove (also known as an ice surge, ice push, ice heave, shoreline ice pileup, ice piling, ice thrust, ice tsunami, ice ride-up, or ''ivu'' in Inupiat) is a surge of ice from an ocean or large lake onto the shore.
Ice shoves are caused by ...
References
Sources
* Dunes Geomorphology Snow or ice weather phenomena {{geomorph-stub