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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

Spreading rate

The speed at which plates separate at a spreading ridge, usually expressed in centimetres per year. A full spreading rate measures separation across both sides; a half rate measures one side’s motion relative to the ridge, so the convention matters.

What to look for

NOAA EMAG2 v3 maps measured magnetic anomalies. Ocean-floor bands record crust formed under changing magnetic polarity. Matching the pattern to dated reversals supports seafloor spreading and allows a rate to be calculated from distance divided by age; colour alone does not give rock age.

Related labs

Seafloor spreading →
EMAG2 global magnetic-anomaly map with alternating anomalies across the ocean floor.
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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.