Dating of rocks fossils and geologic events lab answers
Students not only want to know how old a fossil is, but they want to know how that age was determined.
Some very straightforward principles are used to determine the age of fossils.
Principle of cross-cutting relations: Any geologic feature is younger than anything else that it cuts across.
Some elements have forms (called isotopes) with unstable atomic nuclei that have a tendency to change, or decay.
If the nucleus has not yet decayed, there is always that same, slight chance that it will change in the near future.
Atomic nuclei are held together by an attraction between the large nuclear particles (protons and neutrons) that is known as the "strong nuclear force", which must exceed the electrostatic repulsion between the protons within the nucleus.
After students have decided how to establish the relative age of each rock unit, they should list them under the block, from most recent at the top of the list to oldest at the bottom.The teacher should tell the students that there are two basic principles used by geologists to determine the sequence of ages of rocks.They are: Principle of superposition: Younger sedimentary rocks are deposited on top of older sedimentary rocks.It is estimated to require four hours of class time, including approximately one hour total of occasional instruction and explanation from the teacher and two hours of group (team) and individual activities by the students, plus one hour of discussion among students within the working groups.Explore this link for additional information on the topics covered in this lesson: This activity will help students to have a better understanding of the basic principles used to determine the age of rocks and fossils. Objectives of this activity are: 1) To have students determine relative age of a geologically complex area.