What is Structural Geology?
Structural geology is about deformation structures in rocks, about their
geometry, history, about the reason why they developed and how.
Structural geologists study rock deformation structures and mechanisms to
understand the evolution of the Earth. They do this, for example, to
understand the origin of mountain ranges, or, to make money by unraveling
the present-day structure of, ore deposits, or oil and gas reservoir
rocks. Some structural geologists are involved in understanding Earth
quake mechanisms.
Earth
Structure. An Introduction to Structural Geology and Tectonics (by Ben van
der Pluijm)
At geological time-scale, the Earth is not a rigid sphere like a pebble. Its interior is in motion, the continents move, they are pulled apart, sheared, compressed and deformed. Rocks deform as if they would consist of toothpaste. The result of this can be seen in cross sections through mountain ranges, such as e.g. through the Glarus Alps:
Geological profile through the Glarus Alps by Martin Burkhard, from Burkhard, M. (1990) Aspects of the large.scale deformation in the most external parts of the Swiss Alps (Subalpine Molasse to Jura fold belt) Eclogae geol. Helv. 83 (3), 559-583.
Here are some simple drawings
from simple geological deformation structures.
Examples of geological deformation structures
You can find movies of numerical folding simulations on the homepage of Stephan Schmalholz.
Examples of deformation microstructures
Much nicer examples of microstructures can be found at the homepage of the
Microstructure & Deformation Group in Basel.
And here are some advanced
drawings from microstructures made by Albert Heim in 1878.
Some more small scale structures.
Collection of structural geology slides on the web
Structural
Geology Slide Set (UBC Canada)
Structural Geology Lecture
Slides (UBC Canada)
Geological
structures ... in deformed rocks (University of Newcastle,
Austraila)
Structure slides ... from
the Introductory Geology WebPages at Duke University
Photo index of
a variety of geological features (University of Oregon)
Structural
Geology Photo Gallery (Rick Almendinger, Cornell University)
Images of
Active Tectonics
Macro- to micro-scale
structures in the Assynt region of the Moine thrust belt (Geoff
Lloyd)
The Moine thrust belt
(Rob Butler)
Subalpine Field
Excursion (Rob Butler)
Strike Slip Faults (Arthur
Sylvester)
Microtextures of metamorphic rocks (Index of Minerals in Thinsection)
Microstructures
Online (Monash)
Slide set and notes Deformation Mechanisms & Microstructures Oct. 1998
(J. Tullis, C. Teyssier, H. Stünitz
See also
Structural
Geology on the Web (by Kevin Smart)
Structural
Geology and Metamorphic Petrology on the WWW (by Jürgen Kraus)
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November 2002