Breadcrust bomb near Novarupta, Valley of Ten Thousand Smokes, Memorial . According to the USGS, A breadcrust bomb is a volcanic bomb with a cracked and checkered surface, sometimes resembling the surface of a loaf of bread. The cracks develop when the outer surface of a partially molten lava fragment cools to form a brittle surface and then subsequently cracks as the hot interior expands due to the continued growth of gas bubbles. This bomb has been broken by frost wedging.

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Keywords: alaska, alaskan, america, american, conservation, country, history, katmai, land, lands, national, natural, nature, park, parks, preserve, public, service, smokes, southern, ten, thousand, usa, valley, widlife, wilderness