Deep Time
The Earth is 4.5 billion years old. If you compressed that into 24 hours, the dinosaurs go extinct at 11:39 PM. Humans appear in the last second before midnight. Written history fits in the last milliseconds. We live in a sliver of time we can barely perceive.
James Hutton discovered deep time in the 1780s studying rock formations in Scotland. He saw layers of sediment deposited over ages, then tilted, eroded, and covered by new layers. “No vestige of a beginning, no prospect of an end.” The Earth was ancient beyond reckoning.
Deep time is hard to feel. We can say “million years” but not experience it. John McPhee, who wrote extensively about geology, tried to convey it through metaphor: stretch your arms wide to represent Earth’s history, and a single stroke of a file across your fingernail erases human civilization. The numbers are meaningless until translated into felt proportion.
The concept is disorienting. Everything humans have built exists in what, geologically, is an instant. Mountains rise and erode. Continents drift and collide. Species appear and vanish. The timescale on which these processes operate makes human concerns appear — there’s no avoiding the word — ephemeral.
But something is different now. Human impact operates on geological timescales despite our brief presence. The Anthropocene names an epoch defined by human alteration: atmospheric chemistry changed faster than in past extinction events, species loss rivaling the great dyings, radioactive isotopes from nuclear testing appearing in sediment layers worldwide.
Whether humans will be here in 10,000 years is uncertain. Whether evidence of our presence will remain in rock layers is certain — the signal of our activity is now geological. Deep time will continue; it’s unclear whether we will.
Long-term thinking requires grasping these scales. The Long Now Foundation promotes “long-term thinking” over 10,000 years — long enough to require serious consideration of geological and climatic processes. Their 10,000-year clock is a monument to duration.
Deep time teaches two things at once. Humility: we’re a brief flicker. Responsibility: our brief flicker leaves permanent marks. The rock layers 50 million years from now will show a thin line of plastic, concrete, and isotopes. That’s us.
Go Deeper
Books
- Annals of the Former World by John McPhee — Four books on American geology, Pulitzer Prize. McPhee’s metaphors make deep time feel real.
- Time’s Arrow, Time’s Cycle by Stephen Jay Gould — Intellectual history of how we learned to see geological time.
- The Clock of the Long Now by Stewart Brand — The Long Now Foundation’s 10,000-year perspective.
Essays
- James Hutton’s “Theory of the Earth” (1788) — The original discovery of deep time, presented to the Royal Society of Edinburgh.
- “The Anthropocene: conceptual and historical perspectives” by Will Steffen et al. (2011) — Defining the human epoch.
Places
- The Long Now’s 10,000 Year Clock (under construction in Texas) — Monument to long-term thinking.
- Siccar Point, Scotland — Where Hutton saw the evidence that overturned biblical chronology.
Related: [[time]], [[circadian-rhythms]], [[carrying-capacity]], [[ecology]]