Page 299 - Laboratory Manual in Physical Geology

FAULTED GEOLOGIC STRUCTURES (Brittle Deformation)
STRESS TYPES FAULT TYPES
STRESS TYPES
FAULT TYPES
and the strain (deformation) developed when brittle rocks
they cause deform so much that they break
Slickensides are step-like linear ridges that
develop on fault surfaces as the rock surfaces
scrape against one another. The side of the
fault (now removed) that scraped against this
surface moved down the steps (upper left to
lower right).
Faceted spur
on scarp
Footwall
block Hanging
wall
block

NORMAL FAULTS

Fault
scarp
Fault
Causes lengthening scarp
Graben Horst

REVERSE FAULT
Hanging
wall (High angle)
block
Hanging
wall

Footwall
block

Footwall
Footwall
Hanging wall block
Causes shortening
THRUST FAULT
(Low angle) Footwall block

STRIKE-SLIP FAULTS

Causes tearing and smearing Left Lateral Right Lateral

FIGURE 10.7 Faults (brittle deformation). Three classes of faults result from three kinds of directed pressure (stress: tension,

compression, shear) applied to brittle rocks.
Geologic Structures, Maps, and Block Diagrams ■ 269