These are unusual claims in geology a field that typically

These are unusual claims in geology, a field that typically deals with thick layers of rock accumulated over tens of millions of years, where entire mountain ranges are formed and eroded in a unit of time, where highly accurate rock data – snapshots of one image deep in time – can have an error of 50,000 years, nearly ten times the entire recorded history of humanity. It is extremely unlikely that the tiny patches of artifacts we leave in the few corners of continents where sediments accumulate and are quickly buried – safe from further disfigurement by erosion – will be discovered at any time and somewhere on the surface in the geological future in tens or hundreds of millions of years. The first wave of human-caused extinctions, and the biggest blow to Earth’s megafauna since the extinction of the dinosaurs, began tens of thousands of years ago, when humans began to spread to new continents and islands, destroying everything we think of as Ice Age fauna – mammoths, mastodons, giant wombats, giant sloths, giant armadillos, woolly rhinos, giant beavers, etc. Some eras in Earth’s history go back more than 40 million years, but this new chapter began perhaps 400 years ago, when carbon dioxide levels in the atmosphere dropped a few parts per million. A handful of bones from a layer in Maryland represent the entire early Cretaceous, which covers 45 million years; a Hadrosaurus in New Jersey and part of a Tyrannosaurus in Alabama have been found in the Late Cretaceous, but these are mostly discreet bone and tooth fragments that cover the remaining 34 million years of Earth’s rich history, all the way to Doomsday. If dinosaurs became super-intelligent in the last 7,000 years of their rule, built a civilization, began mining asteroids, and did so for centuries until they forgot to include an asteroid in their orbital calculations, causing the famous 10-kilometer parting stone to rush uselessly toward Earth, it would be nearly impossible to detect. These are planet-changing, transformative paroxysms that last hundreds of thousands of years, altering the trajectory of life and leaving behind only strange black lines in the rocks, buried in the huge cairns that make up later eras. If you were to run a 26.2-mile marathon through the entire history of the Earth, you would traverse two ice ages and more than 150,000 years of the entire history of human civilization on your first pass. Strontium isotopes will tell you that the weathering of rocks around the world accelerated dramatically by tens of thousands of years as violent, suffocating storms attacked rocks and eroded continents during the short-lived CO2 tide. But, as the dinosaur example shows, there is a good chance that a destructive deltaic deposit of cities only a few centuries old will not only be lucky enough to be buried and preserved, but also not to be destroyed later – in the voracious morass of the subduction zone or by sinking too close to the clearing metamorphic forge of the Earth’s mantle, or mutilated in the continental collision that produced the mountains–and then, after all this, in the distant future, by a happy coincidence, it was lucky enough to rise high enough to reach the surface, but not so high that it was quickly destroyed by erosion. is practically zero. If ever in the distant future we manage to do so, it will be an extraordinary testament to the fact that, after a colicky and world-threatening childhood, the species has learned that it is not separate from Earth history, but is an integral part of the systems that have kept this marvelous marble habitable for billions of years. The second great mass extinction, which occurred 70 million years later, lasted 600,000 years, 400,000 years longer than the evolutionary history of Homo sapiens. But what would we have left behind on the seafloor, where most sediments are formed, where most fossils are found, and where we have a slightly better chance of capturing our time in the rocks in a few decades? Many marine fossil deposits have evolved over time