Many minerals. Public domain

There are more than 5,000 minerals in the world—naturally occurring chemical compounds that are stable at room temperature and have a unique chemical formula. But, as Scientific American reports, humans are rapidly adding to that number. In a new report in American Mineralogist, a team of scientists reports that they found 208 new minerals that would never have occurred without humans and thousands more mineral-like compounds that humans have created.

“There is nothing at all like this in the geology of the past 4.5 billion years on Earth,” one geologist told Scientific American.

The new minerals, SciAm reports, formed in conditions created only by humans—in man-made mines with unnatural humidity or in shipwrecks deep on the ocean floor.

Humans have also added thousands of new chemical compounds, many more than were created in the “Great Oxidation Event,” a period that lasted two billion years, when the increase in the supply of oxygen created thousands of oxides.

The compounds that humans have created will change the geological record forever: our most lasting legacy may be in the ground. Like the holes and tunnels humans have created, the earth’s strata will show marks of our presence long after we’re gone. SciAm:

The Washington Monument, for example, will eventually be a lens-shaped pocket composed of limestone where no other limestone is found. And the pocket that was once the Smithsonian will contain so many rare minerals that they could not possibly have formed so close together in nature.

Which means that whoever inherits the Earth will have more than a few geological mysteries to solve.