Geologic Principles and Relative Age Determination

The video tutorial introduces key geologic principles for determining the relative ages of rocks and events, such as superposition, original horizontality, cross-cutting relationships, and contact metamorphism. It then applies these principles to analyze a geologic cross-section, identifying the chronological order of rock layers and events. The tutorial concludes with exercises for students to practice these concepts on additional cross-sections.

Which principle states that in a series of sedimentary rock layers, the oldest layer is at the bottom?

• Principle of Cross-Cutting Relationships

• Principle of Contact Metamorphism

• Principle of Superposition

• Principle of Original Horizontality

What does the principle of original horizontality suggest about sedimentary rocks?

• They are deposited horizontally.

• They are deposited in a circular pattern.

• They are deposited at an angle.

• They are always deposited vertically.

In cross section A, which layer is identified as the youngest?

• Layer J

• Layer F

• Layer N

• Layer A

Why can't igneous intrusion A be the oldest layer in cross section A?

• It is not a sedimentary rock.

• It is not tilted.

• It has contact metamorphism with all layers.

• It is at the top of the sequence.

Which principle helps determine that layer L is older than fault H?

• Principle of Contact Metamorphism

• Principle of Cross-Cutting Relationships

• Principle of Original Horizontality

• Principle of Superposition

How can you tell that layer F is younger than layer K?

• Layer F is tilted.

• Layer F is not tilted.

• Layer K is above layer F.

• Layer K is an igneous intrusion.

What does the principle of contact metamorphism indicate about the relationship between rock J and intrusion A?

• Rock J is older than intrusion A.

• Rock J is not affected by intrusion A.

• Rock J is younger than intrusion A.

• Rock J is the same age as intrusion A.

Which principle would you use to determine that N is older than K?

• Principle of Contact Metamorphism

• Principle of Cross-Cutting Relationships

• Principle of Original Horizontality

• Principle of Superposition

What is the significance of a fault cutting through a rock layer?

• The fault is older than the rock layer.

• The fault and rock layer are the same age.

• The fault is younger than the rock layer.

• The fault does not affect the rock layer.

What should students do after completing cross section A?

• Review cross section A again.

• Discuss cross section A with a partner.

• Work on cross-sections B, C, or D based on their last name.

• Create their own cross-section.