Geologic Structures Diagrams  


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This graph shows the response to increasing stress as applied to two different rock types: BRITTLE vs. DUCTILE/PLASTIC

This graph shows the response to increasing stress as applied to two different rock types: BRITTLE vs. DUCTILE/PLASTIC

 

Definitions:


This Diagram depicts the types of stresses available.

This Diagram depicts the types of stresses available.

 


This diagram depicts some common fold types.

Modified from: Page 374

George H. Davis:  Structural Geology of Rocks and Regions     Copyright  C 1984, by John Wiley & Sons, Inc.

 

This diagram depicts some common fold types.

 


 

This diagram depicts an adjacent ANTICLINE and SYNCLINE with their representative FOLD AXIS and AXIAL PLANES.

Acetate 54 (Figure 14-13)

Syncline and Anticline

C 1992 West Publishing Company

 

This diagram depicts an adjacent ANTICLINE and SYNCLINE with their representative FOLD AXIS and AXIAL PLANES.

 


This Diagram depicts some of the differences between Asymmetrical, Symmetrical, and OVERTURNED folds.

Figure 1.4

Press and Siever:  Understanding Earth           Copyright C 1994 W. H. Freeman and Company

 

This Diagram depicts some of the differences between Asymmetrical, Symmetrical, and OVERTURNED folds.

 


Fold Nomenclature


 

 

More Fold types

More Fold types

 


This diagram shows the affect of plunge on the fold axis.     This diagram shows the affect of plunge on the fold axis.

Figures 11.17 and 11.18 from

George H. Davis:  Structural Geology of Rocks and Regions     Copyright  C 1984, by John Wiley & Sons, Inc.

 

These diagrams show the affect of plunge on the fold axis.

 


 

More Fold Types

More Fold Types

 


Strike and Dip Diagram

59 Strike and Dip Diagram

Plummer, Charles C., and David McGeary, Physical Geology, 6/e.  Copyright C 1993 Wm. C Brown Publishers, Dubuque, Iowa.  All Rights Reserved.


Strike and Dip

STRIKE: The direction of the line formed by the intersection of a horizontal plane with a bedding or fault plane.  The trend of the rock/fault outcrop.

DIP: The angle formed by the intersection of a bedding or fault plane and the horizontal plane; measured in a vertical plane perpendicular to the strike.


This diagram uses Strike and Dip of repeating rock units to produce a geologic map and to infer the underlying fold.

This diagram uses Strike and Dip of repeating rock units to produce a geologic map and to infer the underlying fold.


Block diagram of an Anticline and Syncline.  Hinge Line is the same as the Fold Axis.


Picture of the Virgin (Plunging) Anticline.  Notice the differential weathering of different rock layers, especially on the right side of the image.  This differential weathering allows the tilted/dipping limbs to be more noticeable.  Notice the V-shape of the outcrop pattern.  This ANTICLINE is plunging toward the top of the picture, therefore, it is a PLUNGING ANTICLINE!

Notice the differential weathering of different rock layers, especially on the right side of the image.  This differential weathering allows the tilted/dipping limbs to be more noticeable.  Notice the V-shape of the outcrop pattern.  This ANTICLINE is plunging toward the top of the picture, therefore, it is a PLUNGING ANTICLINE!


Structural Dome and Basin


Fault Propagation Folding

Folding produced by fault action typically produces angular and/or box-folds


Structural Jointing

Notice the affect of differential weathering on the joints in the background on the left side of the image.


Fault Nomenclature

Fault Nomenclature


Fault Types

Fault Types


A and B are REVERSE faults and C is a low-angle reverse fault, typically called a THRUST fault.

A and B are REVERSE faults and C is a low-angle reverse fault, typically called a THRUST fault.


A, B, and C depict Normal Faulting.  In D normal faulting has produced HORSTS and GRABENS.  Horsts are the up-thrown blocks and the Grabens are the down-thrown blocks.  In other words, the Horsts are the ridges and the Grabens are the valleys.

A, B, and C depict Normal Faulting.  In D, normal faulting has produced HORSTS and GRABENS.  Horsts are the up-thrown blocks and the Grabens are the down-thrown blocks.  In other words, the Horsts are the ridges and the Grabens are the valleys.


More Fault types.  Strike-Slip Faults typically have near-vertical fault surfaces.  They also come in two varieties: Left-Lateral Strike-Slip and Right-Lateral Strike-Slip Faults.  Notice the pond in C.  This is a SAG POND, which is usually due to INTERSEISMIC SUBSIDENCE.  Following the release in stress as the result of an Earthquake, the rocks/ground relaxes and subsides, thus forming sag ponds in some situations.

Strike-Slip Faults typically have near-vertical fault surfaces.  They also come in two varieties: Left-Lateral Strike-Slip and Right-Lateral Strike-Slip Faults.  Notice the pond in C.  This is a SAG POND, which is usually due to INTERSEISMIC SUBSIDENCE.  Following the release in stress as the result of an Earthquake, the rocks/ground relaxes and subsides, thus forming sag ponds in some situations.


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