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Geolens

Glossary

417 words used in the labs.

Find a term from the labs, understand the process behind it, and see how it appears in the landscape. Each entry connects an explanation with a real observation and a model you can explore.

Term

Igneous

Describing rock formed when magma or lava cools and crystallises. Slow cooling underground commonly produces larger crystals than rapid cooling at the surface. Texture therefore offers evidence of cooling history, although composition also affects the minerals present.

What to look for

NOAA, Galápagos Rift, 21 July 2011. Lava quenched in seawater forms pillows close to a spreading centre, where new oceanic crust is built.

Related labs

Rock cycle →
Rounded pillow lava on a fissured seafloor at the Galápagos Rift, photographed by a NOAA expedition.
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Explore further with USGS water glossary · USGS volcano glossary · NPS glacial geology · NASA Earth facts. Photograph acknowledgements are collected on the Image credits page.