A crevass, I believe.
its acracked knee cap
Crevasse not to be confused with crevice
Cracks in any ice cap are called crevasses, and because they are subject to shifting and re-shaping, they are not generally named.Antarctica is covered in an ice sheet, and eruptions in that sheet are called nunataks -- mountain tops. Again, any crack in the ice sheet would be a crevasse and would exist without a name.
It is called a "lead", or "polynya"
A Glacier an ice sheet an ice cap
A warm period. But have a crack at "interglacial" in wikipedia.
Ice Wedging Or Frost Wedging
a spring whose water flows from a crack in the cap rock over the aquifer
No, ice cap is a common noun. It is only a proper noun if it is the name of something specific, such as Ice Cap, Alaska or Ice Cap Products.
The ice in Antarctica does crack forming crevasses. This is common in all ice formations.
Cap Polar ice cap Mountain ice cap
The only thing I can get from that question is that there is a hairline crack in the cap.