OBJECTIVE LIFE SCIENCE
DIVERSITY AMONG LIFE FORMS
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Question
[CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
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Are there index fossils in layers above or below it?
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Does the rock layer contain evidence of volcanic activity?
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Either A or B
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None of the above
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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: -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. The boundary between two beds is called a bedding plane.
Detailed explanation-3: -The fossils that are very distinct at certain times of Earth’s history are called index fossils. Index fossils are commonly used to match rock layers. You can see how this works in Figure below. If two rock layers have the same index fossils, then they’re probably about the same age.