The Skutustadir Pseudocraters

What does this formation of craters have to do with water works?  The key to the answer is in the origin.  Lava flowed over wetlands or shallow lake-bottom sediments near present-day Myvatn Lake in Iceland.  The resulting steam pressure built up and blasted holes repeatedly through the same weaknesses in the overlying lava deck.  The resulting flying plumes of rock built craters that look like they are directly volcanic, but really are not rooted in magma, and are known as rootless craters or pseudocraters.  The Myvatn area is littered with these pseudocraters, both in and near the lake; geologists consider them the archetypes for such formations worldwide.

Skutustadir, Iceland (22 Aug 14) Looking NE
65.5679, -17.0361

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