To establish the age of a rock or a fossil, researchers use some type of clock to determine the date it was formed. Geologists commonly use radiometric dating methods, based on the natural radioactive decay of certain elements such as potassium and carbon, as reliable clocks to date ancient events.
How do I know if a rock is radioactive?
Radioactive minerals can be identified with special instruments that detect radiation. The device used to measure this is the Geiger counter. Electric charges develop in a Geiger counter when it is placed near radioactive material; this can measure the presence and intensity of radiation.
How do you get a fossil out of a rock?
0:512:22Preparing fossils: How fossils are removed from rock - YouTubeYouTube
Do rocks Increase Size?
Rocks can grow taller and larger Rocks also grow bigger, heavier and stronger, but it takes a rock thousands or even millions of years to change. Water also contains dissolved metals, which can precipitate out of seawater or freshwater to grow rocks. These rocks are called concretions or nodules.