Reading the bubbles in volcanic glass
Vesicles preserve traces of gas leaving magma, but growth, merger, flow and the cut of a specimen all change the pattern a reader sees.
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Geology
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3 storiesGeology
The missing years inside a rock sequence
An unconformity marks a break in the local rock record. At Siccar Point and Grand Canyon, angles, fossils, mineral ages and fragments of older stone reveal what a missing interval can still tell us.
A river stone keeps only part of its journey
A round pebble has met other surfaces, but its smoothness is no odometer. Rock type, broken edges, intermittent floods and recycled gravel complicate the journey it seems to show.