Faults and Stratigraphy

Flashcards covering the definitions of geological faults, fault elements, types of faults, principles of stratigraphy, contact types, and unconformities based on the lecture notes.

What is the definition of a fault in geology?

A fracture with movement on either side.

What characterizes a dip-slip fault?

Vertical movement where rocks move in the dip direction, often creating fault scraps or cliffs.

How is a strike-slip fault defined?

Horizontal movement where rocks move in the strike direction.

What is an oblique slip fault?

A fault that moves in both horizontal and vertical directions.

In fault elements, what is the 'footwall'?

The rocks located below the fault plane.

In fault elements, what is the 'hanging wall'?

The rocks located above the fault plane.

What are the characteristics of a normal fault?

The footwall (FW) moves up and the hanging wall (HW) moves down; it usually dips steeply at approximately $60^{\circ}$ and is formed by extension.

What are the characteristics of a reverse fault?

The footwall (FW) moves down and the hanging wall (HW) moves up; it usually dips at an angle greater than $45^{\circ}$ and is formed by compression.

What defines a left-lateral strike-slip fault?

The movement of the opposite side is to the left as you look across the fault.

What defines a right-lateral strike-slip fault?

The movement of the opposite side is to the right as you look across the fault.

What is the general definition of stratigraphy?

Correlating sedimentary rock layers according to specific geological principles.

What does the Principle of Superposition state?

Younger rock layers are near the surface, and older rock layers are deposited deeper.

What is the Principle of Original Horizontality?

Sedimentary bedding or strata are formed through the laying of sediments in a horizontal orientation due to gravitational force.

What is the Principle of Original Continuity?

Sedimentary rocks are formed from the same clast or sediments deposited in that geographic area.

What is the definition of Uniformitarianism?

The idea that geological processes, mechanisms, and rock formations that occurred in the past are happening in the same way today.

What is a cross-cutting relationship?

A principle where younger rocks cut across older sedimentary layers, meaning the feature doing the cutting (like an igneous intrusion) is younger.

What is a baked margin in stratigraphy?

A layer of rock changed through intrusions, heat, and/or pressure when rising hot magma interacts with cold pre-existing rock.

What is the Principle of Inclusions?

A collection of inclusions taken from deeper rock layers and deposited in the layers above.

What is an intrusive contact?

A surface where magma has intruded into older rock.

What is a fault contact?

A surface where rocks have moved on either side of the fault.

What is a depositional contact?

A surface where volcanic or sedimentary rocks are deposited on top of older rocks of any type.

What is the geological definition of an unconformity?

A surface representing a period where deposition ceased or erosion occurred.

What is a disconformity?

A type of unconformity characterized by erosion between two parallel sedimentary layers.

What is an angular unconformity?

A type of unconformity characterized by erosion between two nonparallel sedimentary layers.

What is a nonconformity?

An unconformity between horizontal sedimentary rocks and igneous or metamorphic rocks.