How the process works

It takes a great deal of time and patience to find and identify microscopic pieces of debris from volcanoes that erupted hundreds of miles away and tens of thousands of years ago.

First, each 30- to 40-gram sediment sample must be processed to separate out the shards of volcanic glass and anything else of a similar density.

Those tiny particles are then sealed inside a disk of transparent epoxy about the size of a quarter and carefully polished to expose the inside of the grains for examination under a microscope.

UNLV professor emeritus Eugene Smith said there might be 100 grains on a single epoxy disk and only one of those grains — or perhaps none of them — will turn out to be volcanic material.

To confirm whether a shard is indeed a shard, the ones singled out by Smith and his research team are sent to another lab at UNLV, where an electron probe is used to determine their basic chemical composition.

For a full analysis right down to the trace elements, the samples are sent to Michigan State University for tests using a special mass spectrometry device.

Volcanic shards can be incredibly hard to find.

In samples Smith collected in South Africa several years ago, only one out of every 10,000 grains of material turned out to be glass spewed from a volcano.