Blue stripes are often created when a crevice in the ice sheet fills up with melted water and freezes so quickly that no bubbles form. When an iceberg falls into the sea, a layoff salty seawater can freeze to the underside. If this is rich in algae, if can form a green stripe. Brown, black and yellow lines are caused by sediment, picked up when the ice sheet grinds downhill towards the sea. The water froze the instant a wave breaks through ice
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Icebergs in the Antarctic area sometimes have stripes, formed by layers of snow that react to different conditions.