EARTH × TECHNOLOGY

Naming the Chapters

1815 to today

Phanerozoic · Cenozoic · Quaternary · Holocene · Meghalayan

Cambrian, Jurassic, Cretaceous: the names on the strip below this timeline were coined one at a time, from a Welsh tribe, a French mountain range and English chalk, by people who could put the layers in order long before they could put a number on any of them. What made the ordering possible was the discovery that each layer carries its own fossils, and always the same ones.

Why it matters

The shared vocabulary lets a fossil dug up anywhere on Earth take its place in a single story, and the coloured column on this page is made of it. The boundaries still move as dating improves: the chapters are a convention, agreed on and revised, laid over a record that has none of its own.

Dating & uncertainty

The first geological map of a whole country appeared in 1815, and the period names followed one at a time across the nineteenth century. The scale has been under revision ever since, which is why the date on this page has no end.

Sources

1. Wood (2019), Time's Urgency · Petrotemporality at Siccar Point: James Hutton's deep time narrative
2. Witze (2024), Nature · It's final: the Anthropocene is not an epoch, despite protest over vote

Earth history as one day

23:59:59.99604.0 ms before midnight

if Earth’s 4.54 billion years were compressed into a single day