Earth Heritage Glossary
Welcome to the CCW Earth heritage glossary
index page. Over the next year or so, we will be adding more and
more terms to the Earth Heritage glossary, and our other glossary
To find a specific glossary term, try entering the word into the
main glossary search box in the right-hand column of the
Failing that, you can look for a term by browsing through the
glossary index alphabetically, below.
Glossary for letter: U
the surface of contact between two groups of strata which represents a break in the geological record during which there was a combination of no deposition and erosion.