The Monterey excursion
Enormous quantities of organic carbon are buried along the Pacific margin, and the world cools as a result.
- When
- —
- Duration
- 3.4 million years
- Known to
- ± 500 thousand years
- Era
- Miocene, Cenozoic
For over three million years, upwelling along the eastern Pacific margin drives extraordinary marine productivity, and the diatom-rich Monterey Formation and its equivalents bury organic carbon on a vast scale. The carbon isotope record shifts positive worldwide. The Monterey hypothesis holds that this burial drew down atmospheric carbon dioxide and drove the cooling that ended the Miocene optimum — an unusual case of a single sedimentary formation being proposed as a global climate driver. The same rocks are California's principal oil source.