I am no expert in Science, but because these are "ice caps" they would be made out of H2O (water) molecules, but how they got there I don't have a clue. I hope this is the correct answer, Im not to...
Mars has two Ice caps. The North and south Ice caps which both consist of C02 and H20 dry ice. The northern Ice cap is mainly composed of H20 dry ice but the Southern Ice cap is mainly composed of...