A significant amount of carbon-14 was added to the atmosphere from nuclear weapons testing. Since it has a half-life of about 5,000 years, most of it is still around. (The rest of it comes from cosmic rays smashing into atmospheric nitrogen.)
Granted, that's an isotope of a well-known element, not one of the "extra elements tacked to the end of the periodic table". I can point out that [tiny traces of plutonium-244 have been found in the ocean seafloor](https://www.npr.org/2021/05/13/996499035/freshly-made-pluton...). That has a half-life of about 80 million years; it's probably the result of ejecta from a supernova washing over the Earth several million years ago.
Some of the earth is decayed earlier material - radon gas formed here on earth as a daughter product from uranium in granite.
Some of the earth has been created by man on earth in the atomic age ... all those extra elements tacked to the end of the periodic table.