You should see a white crescent called the lunula. The cuticle is the piece of skin that overlaps the hard nail and touches the lunula. You may be wondering what they do, or why you need them. If you get frequent manicures, they may be smooth and even, pushed back as far as they'll go.If not, they may be ragged and torn, or creeping up on the nail.he cuticle is the piece of skin that overlaps the hard nail and touches the lunula. You may be wondering what they do, or why you need them. If you get frequent manicures, they may be smooth and even, pushed back as far as they'll go.
Index fossils. Radiometric dating. The Age of Dinosaurs was so many millions of years ago that it is very difficult to date exactly. Scientists use two kinds of dating techniques to work out the age of rocks and fossils. The first method is called relative dating.
Hafnium-176. 35.9. Radiometric dating using the naturally-occurring radioactive elements is simple in concept even though technically complex. If we know the number of radioactive parent atoms present when a rock formed and the number present now, we can calculate the age of the rock using the decay constant. The oldest rocks on Earth, found in western Greenland, have been dated by four independent radiometric dating methods at 3.7-3.8 billion years. 2  Rocks 3.4-3.6 billion years in age have been found in southern Africa, western Australia, and the Great Lakes region of North America.