DIASTROPHISMDIASTROPHISM

What is Diastrophism?What is Diastrophism?

It is the dynamical forces generally tend It is the dynamical forces generally tend to elevate the earth’s surface.to elevate the earth’s surface.

They are in constant battle against They are in constant battle against external forces that tend to wear away external forces that tend to wear away the land surface.the land surface.

TYPES of EARTH TYPES of EARTH MOVEMENTMOVEMENT

UPLIFTUPLIFT Is the movement of the earth Is the movement of the earth

wherein the crust rises.wherein the crust rises.

SUBSIDENCESUBSIDENCE A sinking or setting of a part of A sinking or setting of a part of

the earth’s crust with respect to the earth’s crust with respect to the surrounding parts.the surrounding parts.

THRUSTTHRUST Horizontal movement of the Horizontal movement of the

earth’s crust.earth’s crust.

THEORIES of THEORIES of DIASTROPHISMDIASTROPHISM

Theories of IsostasyTheories of Isostasy From the greek word meaning “equal From the greek word meaning “equal

standing”standing” States that as rock from higher region is States that as rock from higher region is

removed by erosion and deposited on a removed by erosion and deposited on a lower region, the higher region slowly lower region, the higher region slowly rises while the lower region becomes rises while the lower region becomes heavier and slowly sinks.heavier and slowly sinks.

Contraction Contraction TheoryTheory

States that the earth is gradually States that the earth is gradually shrinking.shrinking.

As the shrinkage occurs, the As the shrinkage occurs, the stronger and heavier blocks of stronger and heavier blocks of the crust sink while the weaker the crust sink while the weaker strata are crowded and strata are crowded and squeezed upwardsqueezed upward. .

CONVECTION CONVECTION THEORYTHEORY

Is a theory which would account for Is a theory which would account for the pushing and folding of rocks the pushing and folding of rocks through convection currents.through convection currents.

This process is true when it occurs This process is true when it occurs under a continental mass.under a continental mass.

STRUCTURAL FEATURES STRUCTURAL FEATURES OF EARTH MOVEMENTOF EARTH MOVEMENT Deformation of rocksDeformation of rocks

The effects of diastrophism is The effects of diastrophism is more clearly seen in rocks, more clearly seen in rocks, especially in sedimentary rocks.especially in sedimentary rocks.

Any deformation of sedimentary Any deformation of sedimentary rocks is shown in tilt, bends, or rocks is shown in tilt, bends, or break in layer.break in layer.

FOLDSFOLDS

A bend or flexure in a rock can be A bend or flexure in a rock can be likened to waves on the ocean.likened to waves on the ocean.

Each has a crust or upfold and a Each has a crust or upfold and a trough or downfold.trough or downfold.

““ANTICLINE”ANTICLINE” The crust of a rock The crust of a rock

““SYNCLINE”SYNCLINE” The trough of the rockThe trough of the rock

DIP and STRIKEDIP and STRIKEDIPDIP

The angle between the The angle between the horizontal plane and a structural horizontal plane and a structural surfacesurface

STRIKESTRIKEThe direction of a line along the The direction of a line along the

edge of an inclined bed where it edge of an inclined bed where it meets the horizontal plane,meets the horizontal plane,

Always at the right of the dip.Always at the right of the dip.

Pitching FoldPitching Fold

Folds whose axes slant downward at Folds whose axes slant downward at each end of an imaginary line running each end of an imaginary line running alone the top of an anticline or along the alone the top of an anticline or along the bottom of a syncline called “AXES of the bottom of a syncline called “AXES of the fold”.fold”.

““PITCH”PITCH” The angel between the axis and the The angel between the axis and the

horizontal.horizontal.

JOINTS and FISSURESJOINTS and FISSURES

JOINTSJOINTS Is a fracture or a little separation Is a fracture or a little separation

between the rock wallsbetween the rock walls

FISSURESFISSURES Cracks or actual gaps between the Cracks or actual gaps between the

rock walls.rock walls.

FAULTINGFAULTING

It refers to the surface along It refers to the surface along which a rock body has been which a rock body has been broken and has been broken and has been displaced.displaced.

2 TYPES OF FAULTING2 TYPES OF FAULTING

1.1. VERTICAL FAULTINGVERTICAL FAULTING Occurs when an entire block of rock is raised Occurs when an entire block of rock is raised

evenly so that the layers remain in their evenly so that the layers remain in their original horizontal position.original horizontal position.

2.2. HORIZONTAL FAULTINGHORIZONTAL FAULTING OCCURS WHEN AN ENTIRE BLOCK OF OCCURS WHEN AN ENTIRE BLOCK OF

ROCK IS LOWERED EVENLY SO THAT ROCK IS LOWERED EVENLY SO THAT LAYERS REMAIN IN THEIR ORIGINAL LAYERS REMAIN IN THEIR ORIGINAL VERTICAL POSITION.VERTICAL POSITION.