A world undone
Around 201 million years ago, the supercontinent Pangaea began to crack. The seams of this rupture were not gentle; they were the site of the Central Atlantic Magmatic Province (CAMP), the most extensive continental flood basalt event in the planet's history. Over a period of about 600,000 years, a series of colossal volcanic pulses tore the continent apart. The total volume of magma involved was staggering, estimated at over 3 million cubic kilometers. This event unfolded across a vast area of more than 10 million square kilometers, leaving behind basaltic dikes, sills, and lava flows from present-day North America to South America, Africa, and Europe.
The eruptions were not a slow leak. The main volcanic activity occurred in at least four distinct pulses, some potentially lasting less than a century each. During these pulses, the eruption rate could have been as high as 8 cubic kilometers per year, a rate more than ten times that of modern eruptions in Hawaii. This immense outpouring of lava wasn't just a geological spectacle; it was a planetary catastrophe. The event caused the Triassic-Jurassic mass extinction, an event that eliminated about 76% of all terrestrial and marine species. This extinction allowed dinosaurs to become the dominant land animals for the next 135 million years.
A toxic aftermath
The CAMP eruptions injected a cocktail of volatile gases into the atmosphere, triggering environmental disasters. Massive releases of carbon dioxide caused intense global warming, while sulfur dioxide emissions led to the formation of sulfate aerosols that caused short-term, sharp cooling events known as volcanic winters. Ocean chemistry was severely altered. Increased atmospheric CO2 led to ocean acidification, which was devastating for marine life with calcium carbonate shells.
The volcanic plumes also carried immense quantities of toxic heavy metals. Sediments from the Triassic-Jurassic boundary show a global spike in mercury, a potent neurotoxin and mutagen. This mercury poisoning had a direct and observable effect on life. Fossilized fern spores from this period show an increase in mutations and malformations. In some samples, nearly all the spores are mutated, recording the planet's poisoning. This evidence suggests the entire food chain was likely contaminated. The long-term environmental instability persisted for over a million years, with mercury being repeatedly remobilized into ecosystems, causing prolonged stress on the biosphere.