IN THE NAME OF ALLAH IN THE NAME OF ALLAH THE MOST BENEFICIENT THE MOST BENEFICIENT

ANDAND THE MOST MERCIFUL.THE MOST MERCIFUL.

Presented By:Presented By:FAZAL ELAHI

Roll # 179

BS. Applied Geology

5th Semester

Evening “B”

2008-2012

Presnted To:Prof. Dr. Mirza Shahid BaigProf. Dr. Mirza Shahid Baig

Presentation Presentation topictopic

• Folds

• Types of Fold

• Geometry of Fold

• Anatomy of Fold

• Tightness of Fold

Fold Description

FoldFolds are bending of rocks due to different forces.

Classification of folds on the Classification of folds on the basis of geometrybasis of geometry

1 Anticline2 Syncline3 Monocline4 Symmetrical folds5 Asymmetrical folds6 Overturned folds7 Recumbent folds8 Isoclinal folds

ANTICLINEANTICLINE• 1 Convex upward.

• 2 The limbs dip away from each other.

• 3 the older rocks in the core and younger rocks along the limbs.

ANTICLINE FOLDANTICLINE FOLD

SYNCLINESYNCLINE• 1 Convex downward

• 2 The limbs dip toward each other.

• 3 Younger rocks in the core and older rocks along the limbs.

MONOCLINEMONOCLINE• The fold in which one limb is dipping and

other limb is horizontal.

SYMMETRICAL FOLDSSYMMETRICAL FOLDS• The folds in which the axial plane is

vertical and which divide the fold into two equal halves.

ASYMMETRICAL FOLDSASYMMETRICAL FOLDS

• The folds in which the axial plane is inclined, and one limb is steeper than other.

OVERTURNED FOLDSOVERTURNED FOLDS

• 1 Axial plane is inclined.• 2 Both limbs dip in same direction.• 3 The limb which has been rotated more than

90 degrees is called overturned limb and other limb is called normal limb.

RECUMBENT FOLDSRECUMBENT FOLDS

• 1 The axial plane is horizontal to sub- horizontal.

• 2 Both limbs are horizontal.

ISOCLINAL FOLDSISOCLINAL FOLDS

• 1 Both limbs dip in same direction and at same angle.

• Profile Plane– The surface perpendicular to the hinge line.

• Inflection Point– The position in a limb where the sense of curvature changes.

• Fold Axis– A cylindrical surface consist of an infinite number of line that are parallel to a generator line.

Anatomy of Folds

Axial PlaneAxial Plane

• Limb– The less curved portion of a fold.

• Plunge– When the fold hinge is inclined to the horizontal.

Anatomy of Folds

Limb

Anatomy of Folds

•Wavelength – The distance between subsequent crests or troughs

•Amplitude – Half the distance from a crest to the subsequent trough

•Crest – The highest point on

the cross section of a fold

•Trough – The lowest point on

the cross section of a fold

Anatomy of Folds

Dome & BasinDome & Basin

• Dome – An antiform where bedding dips away from the central point.

• Basin- A synclinal depression.

                Cylindrical Folds- Cylindrical Folds-                               

• Straight hinge line, Contains fold axes.

Non-Cylindrical Folds- Non-Cylindrical Folds-                               

• Curved hinge lines

Tightness of foldTightness of fold

• Gentle: Interlimb angle 180-170• Open: Interlimb angle 170-90• Tight: Interlimb angle 90-10• Isoclinal: <10

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