• states that sediment layers are deposited in horizontal or nearly horizontal layers due to gravity

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The Principle of Original Horizontality

​This means that any "sloping" of layers must have occurred AFTER the layers formed!

• states that the geologic feature which cuts another is the younger of the two features

• Types:

  • Fault

  • Intrusion

  • Unconformity

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Cross-Cutting
Relationships

• a fracture or break in the Earth's crust where two blocks of rock can move relative to each other, essentially causing a displacement between the rock layers along the fault line

• The fault is YOUNGER than the rock layers around it!

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Faults

​Can you spot the fault?!

• a body of igneous rock, formed from magma that cooled and solidified within the Earth's crust, which has pushed its way into existing rock layers

• The intrusion is YOUNGER than the rock layers around it!

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Intrusions

• caused by a period of erosion or a pause in sediment accumulation, followed by the deposition of sediments

• Angular Unconformity = a gap in the sedimentary record that occurs when younger, flat layers of rock are deposited on top of older, tilted layers of rock

Unconformity