Rocks and Deformation Concepts

A collection of vocabulary flashcards covering key concepts related to rock deformation, structural geology, and geologic mapping.

Deformation

Any change in the original shape, position, or orientation of a rock body.

Geologic Structures

Features that reflect a rocks tectonic history observed in outcrops.

Outcrops

Places where rocks are exposed on Earth's surface.

Folds

Bending of rocks without breaking.

Faults

Fractures in rock with visible movement.

Joints

Cracks in rocks with no movement.

Stress

Force per area that causes deformation in rocks.

Confining Pressure

Equal force applied in all directions.

Differential Stress

Forces that are stronger in one direction causing deformation.

Compressional Stress

Differential stress that squeezes a rock mass. (convergent)

Tensional Stress

Differential stress that pulls apart rock bodies. (divergent)

Shear Stress

Movement of one part of the rock body relative to another. (transform)

Strain

The deformation caused by stress.

Elastic Deformation

Temporary change in shape that returns to original after stress removal.

Brittle Deformation

Rocks that break into smaller pieces due to stress.

Ductile Deformation

Rocks that change shape without breaking.(bend or flow)

Temperature in Rock Behavior

Influences whether rocks exhibit brittle or ductile behavior.

High temp= ductile Low temp= brittle

Rock Type

Affects how rocks deform based on mineral composition and texture.

Strong rock at surface (granite, basalt, quartz sandstone) = Brittle

Weak rock at depth (shale, limestone, rock slat, schist, glacial ice) = Ductile

Time's Effect on Deformation

Slow stress leads to ductile deformation; sudden stress leads to brittle failure.

Anticlines

Folds that resemble an arch where the oldest rocks are in the center.

Synclines

Downfolds in sedimentary strata where the youngest rocks are in the center.

Normal Fault

A fault where the hanging wall moves down relative to the footwall.

Reverse Fault

A fault where the hanging wall moves up relative to the footwall.

Strike-Slip Fault

A fault where the dominant displacement is horizontal.

Dip

The angle at which a rock layer inclines downward from horizontal.

Strike

The compass direction of the line formed by a fault or rock layer and a horizontal plane.

Geologic Maps

Representations that show locations and orientations of rock units at the Earth's surface.

Block Diagrams

Three-dimensional views that visualize rock layers at the surface and underground.