Answer: polarcap

AnswerCrossword Clue
POLARCAP

Topmost region?

POLARCAP

High-latitude formation

POLARCAP

Icy formation at either extremity of the Earth's axis

POLARCAP
Head of the world?
POLARCAP
Planet's icy area
POLARCAPIcy area to the north or south
POLARCAPSource of some icebergs
POLARCAPInuit headgear
POLARCAPMartian feature
POLARCAPIce mass way up north