That's true. But rocks erode at a rapid pace in comparison to the age of the earth. Apparently, very little is left for geologists to study from earlier than ab

That's true. But rocks erode at a rapid pace in comparison to the age of the earth. Apparently, very little is left for geologists to study from earlier than about 1 billion years ago. And there is a tremendous amount of groundwater deep underground, with some of it trapped by rock formations.