There are two classes of icebergs: tabular and non-tabular. A tabular iceberg has steep sides and a flat top. It looks more like a large, flat piece of ice than one would normally picture. A non-tabular iceberg is as it sounds – any iceberg that does not conform to the tabular characteristics. It usually becomes that way because its flat top has eroded into another shape. There are five kinds of non-tabular icebergs: dome, pinnacle, wedge, dry dock and blocky.
In addition to their shape, icebergs are famous for their size and their ability to hide it under water. Typically, only one-tenth of an iceberg’s volume is visible above the water’s surface, while most of its mass is below and therefore unseen. This happens because the density if pure ice is much less than that of seawater.
An iceberg is a large piece of ice from freshwater that has broken off from a snow-formed glacier or ice shelf and is floating in open water. It may subsequently become frozen into pack ice. Alternatively, it may come to rest on the seabed in shallower water, causing ice scour (also known as ice gouging) or becoming an ice island.
Striped icebergs have been spotted in a variety of colors, including brown, black, yellow, and blue.
Icebergs are formed from the glacial ice that has built up from snow falling on the Antarctic continent over millennia. This ice consists of pure fresh water. The ice flows slowly to the coast and breaks off either from glaciers or from ice shelves. Because the ice shelves are very thick and are floating, the seawater beneath them interacts with the glacial ice.
As seawater is drawn deep under the ice shelves by the oceanic currents, it becomes supercooled. Under certain conditions it can freeze to the base of the ice shelf. Because this ice is formed from seawater, it differs from the freshwater ice of the ice shelf. Often, the frozen seawater contains organic matter and minerals, causing it to have a different colour and texture. Thus icebergs broken off from the ice shelves may show layers of the pure blue-white glacial ice and greener ice formed from frozen seawater. As the bergs become fragmented and sculpted by the wind and waves, the different coloured layers can develop striking patterns.
Pure glacial ice, too, can exhibit striking colour patterns. This is thought to be a result of melting that can occur on the continent before the bergs break off. Crevasses high on the Antarctic plateau can fill with melt water and then refreeze, producing layering of blue ice within a white ice matrix. After calving, they begin eroding and the alignment of the stripes can become irregular, leading to icebergs with spectacular appearances.
And from what I’ve gained from other sources, as aquatic wildlife evolves, the deceased animals eventually disintegrate and break into smaller pieces of material. These pieces contribute to some of the blue and green striped icebergs that have been documented. Blue stripes may be formed when water fills cracks in the iceberg and refreezes quickly without air bubbles. Green stripes are also caused by algae particles that become stuck between the ice particles and the ice shelf.
Other icebergs have presented with black, brown, and yellow stripes. If a sheet of ice slides towards the ocean waters it will pick up dirt and particles from the ground. Those particles stick to the ice and are sealed between the new layers of ice to form their own colorful stripes.