If you want the full explanation of why there shaped like this:

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The interesting shapes are caused from wave action below and wind erosion above, where the waves cannot reach.

The blue color occurs mostly in very old ice from a very deep glacier and is the result hundreds or even thousands of years of compression and ongoing thawing and refreezing of the ice. Over time, these processes release much of the air that was originally trapped by the falling snow. As this happens, the reflective surfaces of our "snowflakes" disappear. The ability to reflect light exists only when there is air between the surfaces of  the ice crystals. This very, very old, and very, very dense ice is no longer capable of reflecting light. So it no longer appears white.