Glaciers: Definition, Formation, Types, and Facts

Glaciers

Glaciers are large moving masses of dense ice that are formed when snow is accumulated and exceeds its erosive process of reduces its size, which could be melting and sublimation over many years, most times centuries.

The word glacier was ultimately derived from the Latin word “glacies,” which means “ice.”

Though snow is naturally white, glaciers look bluish as a result of the compressed snow. This is because a large amount of water always appears blue. Water molecules are most likely to absorb other colours more than the colour blue.

Another reason for the bluish appearance of glaciers is their lack of air pockets, which gives white colour to ice, but due to the compaction of snow are squeezed out, thus increasing the density of the resulting ice.

Table of Contents

  • Glacial: relating to or denoting the presence or agency of ice, especially in the form of glaciers. This term also includes other processes and features caused by glaciers.
  • Glaciation: Glaciation is the process that involves the formation, growth, and flow/movement of glaciers.
  • Glaciology: This is an area of study that involves the scientific study of any natural phenomena that require ice, including glaciers. This is also the scientific study of ice in general.

Classification

Glaciers are classified according to their morphology, thermal characteristics, and behaviour.

Classification according to morphology

Alpine glaciers

Alpine glaciers are a type of glacier-formed on the mountains crown and slopes.

This is also known as Valley glacier because it comes in the form of glaciers that fill a valley is called a valley glacier.

Icecap/field

Large masses of glacial ice that astraddle a mountain or a volcano is called an ice cap or an ice field. An Icecap has an expanse that is less than 50,000 km2 (19,000 sq mi).

Continental glaciers

These are Glacial masses bigger than 50,000 km2 (19,000 sq mi).

They have a depth that is several kilometres deep, and they obnubilate the subjacent topography.

Tidewater glaciers

These are glacial masses that ends in the sea.

This includes most glacial bodies moving from Southeast Alaska,  Greenland, Antarctica, Baffin and Ellesmere Islands in Canada.

This type of glacier is said to terminate at the base because as the dense ice masses start getting to the sea, they begin to fall apart into pieces, or they release ice, thereby forming icebergs.

Most of this form of glaciers release ice above sea level, which frequently causes an enormous impact while the iceberg gently taps the water.

Classification by thermal state

Temperate glaciers are at the melting point all through the year, starting from their surfaces to their bases.

The polar glacier’s ice masses are ever below the freezing point, starting from their surfaces to their bases. However, the surface ice pack may go through melting but only seasonally.

The subpolar glacier has both the characteristics of temperate and polar icecaps. Still, it depends on the depth underneath the surface and the slope of the glaciers—position along the length of the glacier.

In that same way, the thermal-based glacier is most times described by the temperature of its base. A cold-based glacier that is below freezing point at the ice-ground contours and these results crystallized to the subjacent substratum.

Glaciers that are warm-based are above or at the freezing point at the contouring line, and can easily slide at any contact.

Formation

Glaciers are formed when snow is accumulated over the years. Glaciers start forming when the snow remains start gathering at a particular all year round until a large amount of snow is accumulated then turns into ice.

Throughout every new year, new layers are accumulated and compressed over the old layers. It is because this compression that forces the gathered snow to recrystallize into grains shapes and sizes that are similar to the shapes and sizes of grains of sugar.

Over the years, these grains gradually grow bigger and bigger while the air spaces between the grains slowly get smaller,  resulting in its compaction into the ice while they increase in density. It could only take about a year before some of the accumulated snow would turn into high-density ice.

As time goes on, those large ice packs would be so compressed under so much pressure that any air bubbles found between them would be tiny and would subsequently disappear to create the high-density ice known as glacial ice.

Structure

Glaciers begin at  an area called “glacier head” and ends at another field called “glacier foot” or “glacier terminus.”

Glaciers are divided into zones according to the snowpack at the surface and melting conditions.

  • The ablation zone is the point where there is a gross loss of glacier ice packs.
  • The accumulation zone is the upper region of a glacial ice mass, where the accretion of snow exceeds the glaciers’ ablation.
  • There is a contouring line dividing the ablation zone and the accumulation zone. This is an equilibrium where the quantity of the newly accumulated snow is equal to the amount of ice lost to the erosive process of reducing glacial ice.

However, the accumulation zone is subdivided into the following based on their melt conditions:

  • The dry snow zone is an area where there is no melting even during the summer, and the gained snowpacks are always dry
  • The percolation zone is a part that has some surface melted or melting, resulting in meltwater percolating into the snow mass. This zone is most times labelled by recrystallized ice lenses, glands, and layers. The snow mass gained, however, never attains the melting point
  • The superimposed ice zone is the zone that is close to the equilibrium line on some glacial ice packs, that is where meltwaters re-crystallizes into cold layers in glaciers, establishing continuous ice packs
  • The snow zone is an area where all of the snow gathered from the ending of the last summer has the temperature raised to 0 °C

The health of a glacier is determined by the glacier ice mass balance. We hope that this article has been helpful. Kindly leave a comment below.

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