This document summarizes a seminar presentation on the attitude of folds in geology. It defines what folds are and their typical parts like limbs, axial plane, and axis. Folds are classified based on their appearance, symmetry, thickness, attitude, and origin. Specifically, the document discusses the different types of fold attitudes including plunging folds, non-plunging folds, doubly plunging folds, and reclined folds. It concludes that the attitude is defined by the axial surface and fold axis, and that domes and basins are examples of doubly plunging folds that can trap oil and gas deposits.

1. A
SEMINAR ON
ATTITUDE OF FOLD
PRESENTED BY;
NONGTHOMBAM SHYAM SINGH
APPLIED GEOLOGY 3rd semester
ROLL NO. 29 GE116029
UNDER THE GUIDANCE OF ;
PROF.DR. B.V.SURESH KUMAR
UNIVERSITY OF MYSORE
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2. CONTENTS
1. WHAT IS FOLD
2. PARTS OF FOLD
3. CLASSIFICATION OF FOLD
4. CONCLUSION.
5. REFERENCES
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WHAT IS FOLD
 Folds may be defined as a curved or crumbling zigzag structures
shown by rock beds. In other words the wavy undulations in the rock
beds are called Folds.
 The bending of rock strata due to compressional forces acting
tangentially or horizontally towards a common point or plane from
opposite direction. The process of folds is called folding.
 Folds shows crests and troughs in alternate manner
 These bends or folds may develops in any type of rock and may be of
any shapes & are best displayed by the sedimentary rocks.
 Its size varies from few displayed by the sedimentary rocks. Its size
varies from few centimetres to in km.

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PARTS OF FOLD
 LIMB- Stretch of rock beds laying between any
crest or any of adjacent toughs on either side
 AXIAL PLANE – Imaginary plane which divides the
fold as symmetrical as possible.
 AXIS – Line of intersection of axial plane with
upper and lower
 HINGE – Line along which a change in the
amount & or direction of dip take place.
 CRESTAL PLANE - Plane or surface formed by all
crest
 TOUGH PLANE - Plane containing tough

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CLASSIFICATION OF FOLD
a) APPERANCE IN CROSS SECTION
b) SYMMETRY OF FOLD
c) THICKNESS OF FOLD
d) INTERLIMB ANGLE
e) ATTITUDE OF FOLD
f) MECHANISM OF FOLD
g) ORIGIN

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a) ATTITUDE OF FOLD
 The attitude of folds (their orientation in
space) is characterized by the attitude of both
their axial surface and their B axis (also called
the fold axis).
 The B axis corresponds to the fold hinge line,
the line linking points of maximum curvature
on a folded surface.
 The axial surface is defined as the surface
containing all the hinge lines on successive
folded surfaces belonging to the same fold
closure.
 The axial surface can be planar of not, and
fold axis can be curved.

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Chiefly four types of folds have been recognised.
1. Plunging fold.
2. Non plunging fold
3. Doubly plunging fold.
4. Reclined fold.

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PLUNGING FOLD –
If the axis is not horizontal. The
amount of plunge being angle
between the axis & horizontal line
lying on common vertical plane.
Pitch – angle between a horizontal
line & axis measured on axial plane.
NON-PLUNGING FOLD
When the axis of fold does not dip in any
direction.

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DOUBLY PUNGING FOLD
 The fold reverses its direction of plunge within
the limits of the area of under consideration. A
fold that plunges in opposite directions from a
central point.
 In a doubly plunging anticline, the plunge is
away from this point; in a doubly plunging
syncline, the plunge is toward this point.
Periclinal structure:
It is commonly include 2 structure.
DOME – it is an anticlinal structrure
which plunges in all direction i.e., is
having quaquaversal dip.
BASIN – It is synclinal depression
with centroversal dip i.e., dip from
all direction towards the central
region. It is also known as
centricline.

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RECLINED FOLD
 The axis plunges directly down
the dip of axial plane.
 A sideways closing fold whose
hinge line is parallel to direction
of dip of the axial plane is called
a neutral or a reclined fold
A typical reclined fold whose hinge plunges down
the dip of its axial surface gently to moderately.

13. CONCLUSION
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 The attitude of folds (their orientation in space) is
characterized by the attitude of both their axial
surface and their B axis (also called the fold axis).
 The axial surface is the surface containing all the
hinge lines on successive folded surfaces belonging
to the same fold closure.
 The axial surface can be planar of not, and fold axis
can be curved.
 A DOME is a doubly plunging anticline. A BASIN is a
doubly plunging syncline.
 Doubly plunging domes are favored locations for oil
and natural gas drilling

14. REFERENCES:
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 A TEXT BOOK OF GEOLOGY by GB MAHAPATRA
 STRUCTURAL GEOLOGY by M.P. BILLINGS
 http://www.gly.uga.edu/railsback/1121PlungingFolds.jpeg
 http://www.jsu.edu/dept/geography/mhill/phylabtwo/lab4/doublesf.html
 http://structuralgeology.50webs.com/reclined.htm
 http://www.geosci.usyd.edu.au/users/prey/Teaching/Geos-2123/Folds/Sld22.html

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