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Use Principle 1: Original Horizontally Principle 2: Superposition, Principle 3:

ID: 108652 • Letter: U

Question

Use Principle 1: Original Horizontally Principle 2: Superposition, Principle 3: Inclusions, Principle 4: Cross-Cutting Relationships and Principle 5: Baked Contacts to determine the relative ages of the various geological features. All the rock layers are sedimentary rocks, except for Unit I and J, which are Igneous plutons Intruding the sedimentary rock. Read over section 9.1 In your textbook Which rock unit it younger- Unit J (Pluton) or Unit H? _ Principle Used _ Which rock unit is older- Unit G or Unit F? _ Principle Used: _ Which rock unit is older- Unit I (Pluton) or Unit C? _ Principle Used: _ Which rock unit it older- Unit I (Dike) or Unit J (Pluton)? _ Principle Used: _ Which is older The River Valley or Unit B? _ Principle Used _.

Explanation / Answer

Question 1:

ANS – Unit J, Principle used: Original Horizontality.

Question 2:

ANS – Unit G, Principle used: Principle of Superposition

Question 3:

ANS – Unit I, Principle used: Cross-cutting Relationships

Question 4:

ANS - Unit I, Principle used: Cross-cutting Relationships

Question 5:

ANS – Unit B, Principle used: Principle of Superposition

Principles used to determine relative age

- Original Horizontality: sedimentary beds deposited near horizontal

- Superposition: layers young from bottom to top

- Lateral Continuity: tapering, thinning near edges

- Cross-cutting Relationships: disrupted pattern is older than disruption, truncation of older rock bodies

- Principle of Inclusions: Once a rock is lithified no other material can be incorporated within its internal structure

- Principle of Fossil Succession: If conditions are right the remains of the dying organisms can then be preserved as fossils within the rock that formed from sediments that covered the remains.