An ice divide is the boundary on an

ice sheet In glaciology, an ice sheet, also known as a continental glacier, is a mass of glacier, glacial ice that covers surrounding terrain and is greater than . The only current ice sheets are the Antarctic ice sheet and the Greenland ice sheet. Ice s ...

ice cap In glaciology, an ice cap is a mass of ice that covers less than of land area (usually covering a highland area). Larger ice masses covering more than are termed ice sheets. Description By definition, ice caps are not constrained by topogra ...

glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier forms where the accumulation of snow exceeds its ablation over many years, often centuries. It acquires ...

separating opposite flow directions of

ice Ice is water that is frozen into a solid state, typically forming at or below temperatures of 0 ° C, 32 ° F, or 273.15 K. It occurs naturally on Earth, on other planets, in Oort cloud objects, and as interstellar ice. As a naturally oc ...

, analogous to a

water divide A drainage divide, water divide, ridgeline, watershed, water parting or height of land is elevated terrain that separates neighboring drainage basins. On rugged land, the divide lies along topographical ridges, and may be in the form of a single ...

. Ice divides are important for geochronological investigations that use

ice core An ice core is a core sample that is typically removed from an ice sheet or a high mountain glacier A glacier (; or ) is a persistent body of dense ice, a form of rock, that is constantly moving downhill under its own weight. A glacier ...

s, since such coring is typically made at highest point of an ice sheet dome to avoid disturbances arising from horizontal ice movement. Ice divides are used for looking at how the atmosphere varied over time. Coring at dome peaks increases precision of reconstructions as it is the place where horizontal motion is at its least. The

Raymond Effect Raymond Effect is a flow effect in ice sheets, occurring at flow divides, which gives rise to disturbances in the stratigraphy, showing unusual arches or anticlines called ''Raymond Arches''. The stratigraphy is detected by radio-echo sounding. T ...

operates at ice divides, creating anticlines in the

radar Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track ...

-detected isochrones, allowing greater capture of older ice when coring. Analysis of ice cores relies on the downward motion of ice, trapping changes of atmospheric gases through time into its layers. Scientist locate ice divides and take ice cores from them, which are typically long cylindrical poles of ice, and analyse them to find chemical elements that the snow and ice transported during that period, e.g. sulfate, nitrate, and other ions. Ice cores are important in determining how our atmosphere has changed, and how we can remedy changes such as the

greenhouse effect The greenhouse effect occurs when greenhouse gases in a planet's atmosphere insulate the planet from losing heat to space, raising its surface temperature. Surface heating can happen from an internal heat source (as in the case of Jupiter) or ...

; scientists found more

greenhouse gas Greenhouse gases (GHGs) are the gases in the atmosphere that raise the surface temperature of planets such as the Earth. Unlike other gases, greenhouse gases absorb the radiations that a planet emits, resulting in the greenhouse effect. T ...

es were in our atmosphere at present than in the past. Scientists from around the United States came together to find the best ice divide in order to go further into the past. They founded the WAIS project, which is funded by the United States National Science Foundation, and is run by scientists from many organizations e.g.

National Ice Core Laboratory The National Science Foundation Ice Core Facility (NSF-ICF), known as the National Ice Core Laboratory (NICL) before 2018, is the primary repository for ice cores collected by the United States. The facility is located at the Denver Federal Cent ...

, Ice Drilling Design and Operations (IDDO), and over fifty universities. The WAIS project is located in West Antarctica, and the goal is to look into the evolution of the

Antarctic ice sheet The Antarctic ice sheet is a continental glacier covering 98% of the Antarctic continent, with an area of and an average thickness of over . It is the largest of Earth's two current ice sheets, containing of ice, which is equivalent to 61% of ...

and

climate Climate is the long-term weather pattern in a region, typically averaged over 30 years. More rigorously, it is the mean and variability of meteorological variables over a time spanning from months to millions of years. Some of the meteoro ...

over the past 100,000 years. The

West Antarctic Ice Sheet The West Antarctic Ice Sheet (WAIS) is the segment of the Antarctic ice sheet, continental ice sheet that covers West Antarctica, the portion of Antarctica on the side of the Transantarctic Mountains that lies in the Western Hemisphere. It is cla ...

(WAIS) is better than other ice divides because of the amount of snow it gets, which means that the layers of ice are thicker. This larger layer thickness means there is a smaller off-set between the ages of the ice and that of the air and gases trapped inside, allowing scientists to make more precise statements about how the atmosphere varied in the past. The success of the WAIS project has educated scientists around the world as to how the atmosphere of Earth has changed dramatically over 100,000 years.

References

Water ice Glaciology {{topography-stub