Page 429 - Geosystems An Introduction to Physical Geography 4th Canadian Edition

Chapter 13 Tectonics, Earthquakes, and Volcanism 393
When forces push rocks together, such as when plates converge, the compression causes a reverse fault, in which rocks move upward along the fault plane (Figure 13.11b). On the surface, it appears similar to a normal fault, al- though more collapse and landslides may occur from the hanging-wall component. In England, when miners
worked along a reverse fault, they would stand on the lower side (footwall) and hang their lanterns on the upper side (hanging wall), giving rise to these terms.
A thrust fault, or overthrust fault, occurs when the fault plane forms a low angle relative to the horizontal, so that the overlying block has shifted far over the underlying
(a) Normal faults, indicated by the arrows, visible along the edges of mountain ranges in California and Utah.
(b) A thrust, or reverse, fault visible in these offset strata in coal seams and volcanic ash in British Columbia.
(c) Aerial view of a right-lateral strike-slip fault in southern Nevada.
Animation
Fault Types, Transform Faults, Plate Margins
Fault plane Fault scarp
Hanging-wall side
(a) Normal fault (tension)
Hanging-wall side
Sierra Nevada
Fault scarp
Fault scarp
Wasatch Mountains
Footwall side
Tensional stress
Hanging wall
Compressional stress (b) Thrust or reverse fault (compression)
Right-lateral* Left-lateral**
(c) Strike-slip fault (lateral shearing)
* Viewed from either dot on each road, movement of opposite side is to the right. ** Viewed from either dot on each road, movement of opposite side is to the left.
▲Figure 13.11 types of faults. [Photographs by (a) Bobbé Christopherson. (b) Fletcher and Baylis/Photo Researchers, Inc. (c) Marli Bryant Miller.]
Footwall side
Footwall
Fault