Historical Geology 102
Geologic Time Study Guide


After the "Geologic Time" lecture and readings you should be able to answer and discuss the following questions.

What is time?

What are the common units of timekeeping, from shortest unit to longest unit?

Upon what physical process or condition is each of these common units based?

How is one year defined?

How many days long is one year?

What is the difference between common time and geologic time?

How old is the Earth?

What is the Geologic Time Scale?

What are the six major divisions of the Geologic Time Scale?

Upon what principle is the Relative Dating technique based?

Describe the Principle of Superposition.

Describe the Principle of Original Horizontality.

Describe the Principle of Lateral Continuity.

Describe the Principle of Cross-cutting Relations.

Describe the Principle of Inclusions.

Describe the Principle of Unconformities.

What are the three types of unconformities and what is the relationship between rocks above and below the unconformity?

Describe the Principle of Biologic Sucession.

Describe the Theory of Evolution based on Natural Selection.

Who originally described the Principle of Evolution based on Natural Selection?

Describe the Principle of Uniformitarianism.

Upon what principle is the Absolute Dating technique based?

What is the radiometric dating technique?

Describe alpha decay.

Describe beta decay.

What is meant by the terms parent isotope and daughter isotope, and what is the relation between the two?

What is the half-life decay rate?

How are the parent isotope, daughter isotope, and half-life all used to determine the absolute age?

What are some of the useful radioactive isotopes?