GEOLOGY

Detailed explanation-1: -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.

Detailed explanation-2: -First and foremost, they use the law of superposition to determine the relative ages of sedimentary rock layers. According to the law of superposition, in horizontal sedimentary rock layers the oldest is at the bottom. Each higher layer is younger than the layer below it.

Detailed explanation-3: -But, how can we determine how old a rock formation is, if it hasn’t previously been dated? Scientists can use certain types of fossils referred to as index fossils to assist in relative dating via correlation. Index fossils are fossils that are known to only occur within a very specific age range.

Detailed explanation-4: -Scientists commonly study the layers in sedimentary rocks to determine the relative age of rocks. Sedimentary rocks form when new sediments are deposited on top of old layers of sediment. As the sediments accumulate, they harden into layers called beds.