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PALEONTOLOGY, AND in particular the study of dinosaurs, is an exciting topic to people of all ages.Although most attention in today's world focuses on dinosaurs and why they became extinct, the world of paleontology includes many other interesting organisms which tell us about Earth's past history.If certain fossils are typically found only in a particular rock unit and are found in many places worldwide, they may be useful as index or guide fossils in determining the age of undated strata.By using this information from rock formations in various parts of the world and correlating the studies, scientists have been able to establish the geologic time scale.The fossils represented by the letters on this card are "younger" than the "T" or "C" fossils on the "TC" card which represents fossils in the oldest rock layer.Sequence the remaining cards by using the same process.Scientists also use direct evidence from observations of the rock layers themselves to help determine the relative age of rock layers.Specific rock formations are indicative of a particular type of environment existing when the rock was being formed.
Return to top The study and comparison of exposed rock layers or strata in various parts of the earth led scientists in the early 19th century to propose that the rock layers could be correlated from place to place.
*Life Science: Fossils indicate that many organisms that lived long ago are extinct.
Extinction of species is common; most of the species that have lived on the earth no longer exist.
This relative time scale divides the vast amount of earth history into various sections based on geological events (sea encroachments, mountain-building, and depositional events), and notable biological events (appearance, relative abundance, or extinction of certain life forms).
Objectives: When you complete this activity, you will be able to: (1) sequence information using items which overlap specific sets; (2) relate sequencing to the Law of Superposition; and (3) show how fossils can be used to give relative dates to rock layers.