Relative dating of rocks and events
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.
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.
This would also mean that fossils found in the deepest layer of rocks in an area would represent the oldest forms of life in that particular rock formation.
By correlating fossils from various parts of the world, scientists are able to give relative ages to particular strata. Relative dating tells scientists if a rock layer is "older" or "younger" than another.
Locally, physical characteristics of rocks can be compared and correlated.
On a larger scale, even between continents, fossil evidence can help in correlating rock layers.
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.