The Fall From Grace

"To hit bottom is to fall from grace." -Douglas Horton

The HEDORAH Alone had wandered the earth for 100 years, all the while pumping out acidic compounds that dissolved limestone and shale underground. This dissolution sped up the growth of the world’s Acid Caverns, creating a mostly hollow surface of the earth. And when a Magnitude 9 earthquake shook the entire planet one fateful day in July, the stress was too much for the rock to take, and the entire Acid Caverns collapsed, bringing down the surface world with them. This fall destroyed entire landscapes, dropped entire species to their doom, and caused landslides worldwide, wiping out thousands of species. The Fall decimated the Acid Cavern ecosystems, and the acidic gasses once trapped in the caves were released into the air, warming the planet. This warming coupled with the ocean acidification from the hedrium extinguished even more life than the Fall, and was the main cause of the mass extinction.
This fall was also the end of the HEDORAH’s reign of terror, as the crumbling earth exposed a massive geyser in Yellowstone, and the colony happened to be standing right above it. The trillions of tiny crustaceans were immediately boiled alive, not even one remaining.
Despite all this, this extinction was extremely minimal by mass extinction standards, only wiping out 45% of life. But it was still large enough to officially end the Microcene, and usher in the next era, one of the strangest of them all. The Unitatemocene.