Racetrack Playa, California: Even NASA can't explain it. Rocks, some weighing hundreds of pounds sliding across the sediment, leaving furrows in their wakes, the land being completely flat and covered with cracked mud...how is that possible. No one has actually witnessed it, and no one can explain.
This up to 1000 years old snow has metamorphosed into highly pressurized glacier ice that contains almost no air bubbles. Thus it absorbs the visible light despite the scattered shortest blue fraction, giving it its distinct deep blue waved appearance. This cavity in the glacier ice formed as a result of a glacial mill, or moulin. / Svínafellsjökull glacier in Skaftafell, Iceland