Age· The columns of time
Calabrian
1.8 Ma → 774 ka
An age defined by a golden spike that had already served once: it carried the base of the Quaternary until 2009, and was given this new job in 2011.
What the evidence shows
The Vrica section in Calabria had carried the base of the Quaternary since 1985, at 1.80 million years. When that base was lowered to 2.58 million in 2009, the section did not become useless: it was repurposed in 2011 to define the Calabrian instead, and a golden spike that had meant one thing came to mean another without moving a centimetre. Inside the age, glacial cycles run at their shorter rhythm, and hominins are spreading across Africa and Eurasia. Burnt bone and ashed plant remains inside Wonderwerk Cave in South Africa, dated to about a million years, are the oldest secure evidence of fire in a place where hominins lived. Towards its end the glacial rhythm begins to change, from short cycles to the longer and deeper ones that will run for the rest of the Quaternary.
Bounds and conventions
The boundary is firm, since it was an established marker before it was a Calabrian one. The shift in glacial rhythm that begins in this age has no agreed cause, which is why it is called the mid-Pleistocene enigma. And the Wonderwerk evidence shows fire in a cave, which is not the same as showing that its occupants could make one.
The Vrica GSSP, reassigned in 2011.
Sources
- Cohen, K. M., Finney, S. C., Gibbard, P. L., Fan, J.-X. (2013). The ICS International Chronostratigraphic Chart. Episodes 36(3), 199–204, mise à jour continue, voir Cohen et al. (2025), Episodes.
- Head, M. J. (2019). Formal subdivision of the Quaternary System/Period: Present status and future directions. Quaternary International 500, 32–51.
- Berna et al. (2012), PNAS · Microstratigraphic evidence of in situ fire in the Acheulean strata of Wonderwerk Cave, Northern Cape province, South Africa
- Ford & Chalk (2020), Oceanography · The mid-Pleistocene enigma