Relative dating geology examples
The study of fossils and the exploration of what they tell scientists about past climates and environments on Earth can be an interesting study for students of all ages.Teaching about Earth's history is a challenge for all teachers.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.
The first card in the sequence has "Card 1, Set A" in the lower left-hand corner and represents the bottom of the sequence.
For example, most limestones represent marine environments, whereas, sandstones with ripple marks might indicate a shoreline habitat or a riverbed.
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.
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 Law of Superposition, which states that in an undisturbed horizontal sequence of rocks, the oldest rock layers will be on the bottom, with successively younger rocks on top of these, helps geologists correlate rock layers around the world.