It must be understood that the ice of continental Antarctica does not form as a result of water freezing. Rather, the ice is produced as a result of air being forced out of snowflakes through the tremendous weight of snow upon snow upon snow over eons of time. It is hard to imagine how much pressure exists at the bottom of the East Ice Sheet that averages just over three kilometers in thickness. Glaciation in Antarctica occurs on a monster scale!

Only sea ice on the Southern Ocean that surrounds the continent forms as a result of freezing water.

The base of the East Antarctic Ice Sheet is foredeepened with the basement under the interior being actually deeper than that under the edges of the ice sheet. The land is shaped somewhat like a shallow bowl beneath the ice sheet. Foredeepening occurs as a result of two factors. The first is that the tremendous weight of the ice sheet actually depresses the bedrock. This is called glacial-isostatic depression. The second factor contributing to the foredeepening is the erosion by the ice sheet itself. The interior ice is much thicker; therefore the erosion it produces is much greater in the middle than at the edges. The land-based sheet is considered stable relative to the marine-based sheet. Unless a catastrophe of huge proportions occurs to change its balance, the land-based sheet will react slowly and consistently to changes in the environment.

Ice streams are rapidly flowing rivers of ice that form in regions where ice sheets converge. Ice is pulled from the ice sheet interior. The rate of  pulling" is influenced by the thickness of the ice, the steepness of the ice surface and how much water is flowing under the glacier. Ice streams and outlet glaciers are the fastest moving parts of an ice sheet. They are directly responsible for draining the ice away. If the streams of ice are separated by exposed topography such as the Transantarctic Mountains, the streams are called outlet glaciers. If the streams of ice are not separated by topography, they are called ice streams, but only if their edges touch.

Presently, much of the West Antarctic Ice Sheet is grounded well over a kilometer below sea level, and more than two kilometers below sea level at approximately its center. The basement of the West Antarctic Ice Sheet is foredeepened as well. Much of the ice drainage from West Antarctica is convergent to the coast. The result is a series of rapidly flowing ice streams. Most of the ice drained from the West Antarctic Sheet flows either into the Ross Ice Shelf in Ross Sea, or the Ronne-Filchner Ice Shelf complex in Weddell Sea. Loss of ice from the West Antarctic Ice Sheet is a result of icebergs calving from the ice shelves. Marine-based ice sheets are fairly unstable because they are inextricably linked to the sea, and any changes in the ocean can impact their balance. Any external factor that increases the calving rate will pull the ice faster and faster and result in a positive feedback loop that will eventually drain all of the ice from its interior.

Ice moves in three ways: internal deformation, basal sliding and bed deformation. Ice always moves in the same direction, that is, to its "nose" under the effect of gravity, whether it is "advancing" or "retreating". Retreating ice means that ablation (ice that is released by evaporation, melting or calving) exceeds accumulation ( the formation of new ice ), and thus the mass of ice is decreasing. Ice deforms under its own weight as a result of the pull of gravity and pressure from above. The thicker the ice, the faster the ice flows. The warmer the ice, the faster the movement. The higher the pressure, the faster it flows. Movement by internal deformation is very slow. The second way ice moves is by basal sliding caused by water at the base of the glacier. High pressure actually reduces the temperature at which ice will melt from 0 Celsius to as low as -2.8 Celsius. The thicker the ice, the lower the ice melting point will be which raises the likelihood that water will be present at the glacier base to help movement. Water reduces the friction of the ice against the material below, allowing faster movement. Basal sliding produces a movement ten times faster than internal deformation. The third way ice moves is by deforming substrate. Sediment or the rock debris under the ice sheet increases movement at the glacier base and actually carries the ice sheet along with it.

When ice streams reach the coast, they pass over many irregular rocks and terrain and anchor themselves to the terrain as they continue out into the ocean. The ice slowly grows outward onto the water producing a large, floating ice shelf anchored, but hinged, to the continent. Ice shelves cover roughly 50% of the Antarctic coast. The Ross Ice Shelf in West Antarctica is by far the largest individual shelf. Its area is the size of France and is fed by seven ice streams. Ice shelves continually float up and down with the tides, all the while grinding and grating against the rocks. This eventually causes them to break apart. Large cracks, crevasses and the ice formation called sastrugi, characterized by crests and troughs, results from this constant, violent process. The tides themselves will eventually destroy an entire shelf over a long period of time. The edges of the ice shelves break off, or calve, forming icebergs every year as a result of summer seasonal warming. As the climate warms more rapidly in the future, scientists believe that the Antarctic ice shelves will likely destabilize at a faster rate. The recent collapse of ice shelves in the Antarctic peninsula region is thought to be evidence supporting this belief.

Ice tongues are long, narrow features of floating ice. Drygalski Ice Tongue is the largest on the continent. Icebergs are pieces of floating ice with less than 15% of the entire mass of the ‘berg visible. They calve, or break off from ice tongues, glaciers, ice shelves and the edges of ice sheets. Icebergs can be huge and weighing millions of tons. Iceberg B-9 that calved from the Ross Ice Shelf in 1987 was nearly the size of Prince Edward Island.

The sea ice that covers the Antarctic perimeter is one of the most climatically important features of the Southern Hemisphere, dramatically influencing the global atmosphere and oceanic circulation. Each year, the area of sea ice around Antarctica increases and decreases in an ancient cycle. In March, the ice is at its minimum, covering only 4 million square kilometers, or 11% of the Southern Ocean’s total area. It reaches its maximum extent in September when it grows to cover nearly 20 million square kilometers, about 57% of the Southern Ocean’s total surface area. All that ice significantly reduces the amount of solar radiation absorbed at Earth’s surface and restricts the amount of heat transferred from ocean to atmosphere.

Antarctic sea ice forms in a well-defined pattern. It starts to form in autumn when the air is still and the water surface chills below the freezing point. Seawater of average salt content (about 35 parts of salt per thousand parts of water) freezes at about - 1.9º C (28.8º F). It first forms as fine hexagonal crystals on the surface of the supercooled brine. But, only the water freezes; the salts are left behind - no room for them is left in the growing network of ice. In stable water, the crystals typically grow side by side in small platelets, coating the surface with an oily looking sheen called "grease ice."

Below the surface, particularly in open or turbulent waters, where the crystals are constantly jostled, an unstructured briny slush called "frazil ice" accumulates against the underside of the existing ice cover. Most areas of the sea ice begin as a composite mixture of grease and frazil ice to form a soupy layer. As freezing continues, a dense suspension of frazil ice grows and, broken up by wind and waves into separate masses, forms plates of "pancake ice."

If the ice forms quickly, significant amounts of brine are trapped within the ice matrix in channels and pockets. This type of sea ice has a high salinity (~20 parts per thousand) and forms critical habitat for a variety of microscopic organisms. If this final freezing happens slowly, the pockets of brine between the plates are squeezed out and a dense, salty solution drains beneath the growing ice. Slowly formed sea ice has a low salinity of 2 to 10 parts of salt per thousand parts of water.

Pancake plates collide with one another as they move about the surface of the freezing sea, their edges becoming curled into giant lily pads, some 3 to 5 meters across and perhaps 50 cm thick. The pancakes begin to freeze together in groups, acquiring additional layers of frazil ice from below and a covering of snow on top. Jumbled together and rafted over one another, glued by the frazil ice, the growing layer of sea ice has a very jagged underside. Doubling and tripling in thickness, this layer is broken continuously by waves until "pack ice" forms. In the deepening cold of winter, the pack forms a continuous expanse of rough, uneven sea ice. It is this floating pack ice that has such a profound effect on the exchange of heat between the atmosphere and the ocean.

Where the open ocean reflects only about 5% of incoming solar radiation, snow-covered pack ice reflects over 80%! Even as the sun returns to the spring sky, the reflection of that much heat away from the Earth delays the normal warming that the sun would bring. During the dark months of winter with so little solar radiation to warm the area, temperatures drop even further, leaving Antarctica bitterly cold.

Within sea ice, thriving in pockets of brine, are hundreds of species of plankton. Not only does the sea ice provide a floating home for many organisms, it also serves, on its peripheries at the ice/ water interface, as an area where microalgae attach to the undersides and edges of the ice. When this ice melts as summer warms the region, the algae and other organisms are released back into the sea to be quickly snatched up by seabirds. Plankton-feeding whales are especially attracted to retreating ice edges, for the plankton is released in shoals thick enough for them to feed on. The thick mats of algae also provide a rich harvest for krill.

Brash ice is a slushy mixture (much like crushed ice) of older and newer tiny ice pieces that have been broken off from their original floes or other chunks of pack ice. It fills up the spaces between the various pieces of pack ice. It eventually freezes tight with the sea or pack ice around it to make a rather rough but quite solid, strong floating sheet of ice.