Hirnantian
Hirnantian is a age-level unit in the ICS 2026/06 timescale, displayed here from 445.2 to 443.1 Ma.
Evidence boundary
eag and lag are display projections of the versioned boundary records below. Phanerozoic numerical ages do not define the units; their GSSPs do. null uncertainty means the chart publishes a fixed GSSA/display value without an uncertainty in the numerical-age column.
Older boundary: 445.2 ± 0.9 Ma · Younger boundary: 443.1 ± 1 Ma · gtsd:Hirnantian
Numerical ages are versioned display values; Phanerozoic units are defined by GSSPs rather than by the numerical ages themselves.
References
- International Chronostratigraphic Chart v2026/06Cohen, K.M.; Harper, D.A.T.; Gibbard, P.L.; Car, N. · 2026 · DOI 10.18814/epiiugs/2025/025001