It's like those pesky mechanics finding problems with cars. And those doctors finding illnesses in people. ****s, the lot of them.
Dinosaur bones have been found for hundreds of years too. Once you find them it's just a big jigsaw puzzle.
Probably were found before that. Mibby where myths of monsters came from. As time goes by some places are eroded. Earthquakes, tectonic plate movement and the such also cause the Earths surface to be sometimes violently moved around. That might uncover stuff. I ain't no geologist so what do I know.