First, a citation about layers in rock (14)

I believe the answer is:

stratification

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'layers in rock' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Maybe they are linked in a way I don't understand?

'first a citation about' is the wordplay.
'about' is an anagram indicator.
'first'+'a'+'citation'='firstacitation'
'firstacitation' is an anagram of 'STRATIFICATION'.

Can you help me to learn more?

I've seen this clue in The Daily Express.

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