Geological Principles and Relationships

The video tutorial by Mr. Selig covers the concept of relative time in geology, focusing on the sequential order of geologic events. It introduces key principles such as the law of original horizontality, which states that sediments are deposited horizontally, and the principle of superposition, where the oldest rocks are at the bottom in undisturbed sequences. The tutorial also explains unconformities, which are erosional surfaces indicating a gap in deposition, and the law of cross-cutting relationships, where faults or intrusions are younger than the rocks they cut through. Real-world examples from western New York are used to illustrate these concepts.

What is the primary purpose of using symbols in geologic diagrams?

• To confuse the reader

• To indicate the age of the rocks

• To represent different types of rock layers

• To make diagrams look more colorful

According to the Law of Original Horizontality, how are sedimentary rock layers typically deposited?

• Randomly

• Horizontally

• In a circular pattern

• Vertically

What does the Principle of Superposition state about the age of rock layers?

• All rocks are the same age

• The oldest rocks are on the top

• The age of rocks cannot be determined

• The oldest rocks are on the bottom

What is an unconformity in geological terms?

• A type of igneous rock

• A symbol used in diagrams

• A buried erosional surface between rock layers of different ages

• A continuous sequence of rock layers

How is an unconformity typically represented in a diagram?

• With a straight line

• With a wavy line

• With a zigzag line

• With a dotted line

What is the significance of identifying fossils from different time periods in rock layers?

• It suggests a period of erosion or non-deposition

• It indicates continuous deposition

• It means the fossils are not useful for dating

• It shows that the layers are the same age

What does the Law of Cross-Cutting Relationships tell us about faults?

• Faults are the same age as the rocks they cut through

• Faults do not affect the age of rocks

• Faults are younger than the rocks they cut through

• Faults are older than the rocks they cut through

In the context of cross-cutting relationships, what can be inferred if an igneous intrusion cuts through sedimentary layers?

• The sedimentary layers are younger than the intrusion

• The intrusion is older than the sedimentary layers

• The intrusion and sedimentary layers are the same age

• The intrusion is younger than the sedimentary layers

What is indicated by the presence of contact metamorphism around an igneous intrusion?

• The surrounding rocks are igneous

• The intrusion is older than the surrounding rocks

• The surrounding rock layers were never heated

• The surrounding rock layers were heated after the intrusion

What does the presence of a fault splitting an intrusion suggest about their relative ages?

• The fault is younger than the intrusion

• The fault is older than the intrusion

• The fault and intrusion are the same age

• The fault has no relation to the intrusion