Geological time units and correlation
Geological history is organized into nested eons, eras, periods, epochs and ages.
Key knowledge
Geological history is organized into nested eons, eras, periods, epochs and ages. Rock successions and fossil correlation established relative ordering; numerical dating supplies additional age constraints. The International Commission on Stratigraphy maintains a revised global framework whose boundary definitions and numerical estimates must be distinguished.
Conditions and scope
- A time interval and the corresponding body of rock are related but differently named concepts.
- Numerical ages are dated reference estimates rather than immutable constants; no obsolete boundary ages are supplied here.
Sources · 1
References
Sources retain their recorded scope. A source link alone does not establish verification of every statement.
Evidence and review
Read relative-versus-isotopic history, nested units and ICS maintenance paragraphs; excluded reversed Hadean age typo and outdated Phanerozoic/Cenozoic boundary estimates.
2026-10-10 · Independent AI editorial review: All36 Life-authored Earth compact statements/conditions/displayed equations and all81 origin semantic links read; all36 author exact-source matrix rows and exclusions assessed. All18 inherited Earth compact records read for combined inventory. Targeted independent actual primary sections listed below; not every source body or proof independently reread. AI editorial reference review, not human certification/field proficiency or whole-field completion. Receipt: earth-life-independent-content-review.1.
Entry details
Permanent link to this entry ↗- Record identity
- uni-earth-geologic-time
- Revision
- core.1
- Structured reference record
- University core expansion