Aim
Earth History is divided into time units based on the fossils. Students will use the internet to learn the age relationship among bodies of rocks using different principles. They will use additional information such as volcanic ash layers and index fossils and calculate the rate of decay (half-life) of radioactive isotopes. This will allow the students to determine the absolute ages of materials found in rocks.
Audience
This unit is intended for grades 9-12 students preparing for Earth Science Regents Examination. The curriculum has been modified to address multiple learning in the classroom and involve parents in the learning process.
Subject-matter
To reconstruct the geologic history use the following procedures:
1 Geologic Time Scale
- It is divided into 4 eras
- The black vertical stripes indicate times for which New York States has rocks
- The letters indicate the time distribution of fossils
2 Relative Dating
- Principle of Uniformitarianism
- Principle of Superposition
- Principle of Original Horizontality
- Cross-cutting relationships (faults, fold, intrusions and extrusion)
- Unconformities
3 Correlation
- Process of showing that rocks or geologic events from different areas are the same age.
- Index fossils - must have lived over a large geographic area and must have existed for a short period of geologic time.
4 Radioactive Dating (Absolute Dating)
- Use radioactive isotopes (Carbon-14, Uranium-238, Potassium-40)
- Half-life (See Reference Table front cover-Radioactive Decay Data)
Earth Science Standard 3 Earth and Space Sciences Concepts
S3c Demonstrates an understanding of origin and evolution of the Earth system.
Standard 5 Scientific Thinking
S5c Uses evidence from reliable sources to develop descriptions,explanations, and models; and makes appropriate adjustments and improvements.
Standard 6 Scientific Tools and Technologies
S6d Acquires information from multiple sources
Performance Objectives
- Identify the characteristics of life and two ideas about how it may have originated.
- Explain how a study of fossil record shows that life-forms have evolved through geologic time.
- Describe how fossils provide evidence of past environments.
- Determine the relative age of a series of rock layers and any igneous intrusions, faults, folds, or fossils that they may contain, based upon the principle of superposition.
- Explain the significance of index fossils and volcanic ash deposit in correlating widely separated rock layers.
- Interpret the geologic time scale.
- Determine the absolute age of a rock given the relative amounts of a radioactive isotope and decay product in the rock, and the half-life of the radioactive isotope.
