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Bombs

I've mentioned volcanic bombs several times. A bomb, as pictured here, is a slug of hot lava spewed from the volcano which cools in the air. Some bombs are obviously streamlined, from cooling in flight. At Erebus, the bombs expand while they cool, sometimes forming a hollow center. The inner rock is highly vesicular (bubbly) to the point of looking spider-webby, with progressively more solid rock towards the outside. Also, amazingly, though the rock looks solid, and contains big crystals like the lava flows, it is very easily stabbed with the tip of an ice axe--it's more the softness of pumice, for those of you familiar with pumice.

Unfortunately, there's no scale on this shot. The bomb is probably about two feet tall. Some of them are up to six feet long, and flatened like a pancake.