what do u mean if meters hit the earth? do you mean meteors? if that's what you meant, there are traces of meteors. the thing is that, the earth is still an alive planet unlike mercury, and the moon so the surface is constantly but very slowly changing due to the difference in temperature between the core and the surface. If it wasn't for the massive size of Earth, the planet would look like the moon. The moon is actually a chunk of the Earth that was blasted off by a meteor billions of years ago. The surface of the Earth is continuously being altered through many processes such as erosion, volcanic eruptions, tectonic plates, and so on. Just read up on it, pretty interesting stuff.