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Biology Chapter 19

Terms to do with the History of Life

TermDefinition
Extinct A species that has died out
Paleontologists Researchers who study fossils to learn about ancient life such as the structure of ancient organisms, their environment, and the way they lived
Relative Dating Determines the relative age of a rock layer or fossil by comparing its placement with that of fossils in other rock layers.
Index Fossils Used when scientists need to correlate the relative ages of the rock layers that carry them distant places
Radiometric Dating Relies on radioactive elements which decay or breakdown into nonradioactive elements at a steady rate
Half-life The time required for half of the radioactive atoms in a sample to decay
Geologic Time Scale A timeline of Earth that geologists and paleontologists have built
Eras What eons are divided into
Periods What eras are divided into (ranging in length from hundreds of millions of years to just 2 million years)
Plate Tectonics Huge plates that move in the past and continue to move on in the Earth's outermost layer
Created by: nelska09