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Volcanic ash magnified 525 times.
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Ashfall skeletons are buried in a bed of pure volcanic ash.
Volcanic ash consists of tiny shards of glass from broken glass
bubbles. These glass bubbles form and then break apart during
powerful volcanic eruptions.
The ash particles are small enough to have been breathed deeply into the lungs of animals when volcanic ash blanketed northern Nebraska 12 million (12,000,000) years ago.
At the Ashfall fossil site in northeast Nebraska, the ground beneath the soil looks something like this in cross-sectional view.
Sedimentary rock layers (strata) contain fossils that reveal clues to environmental conditions and the animal life of specific times in the past. The particles of sediment that make up the rock reveal clues about the environmental setting and how the rock was deposited.
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 An aerial view of a portion of the Ashfall site. MORE
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