The beds of undisturbed sedimentary rock formations generally occur in horizontal disposition(प्रकृति). during earth movements,the strata may be tilted out of horizontal.such inclined rock beds are said to have a "Dip".

1} Dip & Strike

•Dip-- Dip is basically an angle of inclination of Rock beds with horizontal plane.

~True dip & Apparent dip--

-Maximum Angle of dip on rock bed is called "True Dip". it is measured in the direction at right angles to the strike.

-A Dip measured in any other direction than true dip is called "Apparent Dip".

•Strike-- It is the direction of line formed by the intersection of a bedding plane & horizontal plane.

Dip angle is measured by Clinometer & Its direction is measured with compass.

Dip varies from 0°to 90°.

Apparent dip is always less than True Dip.

True Dip & Strike are always perpendicular to each other.

2} Fold,Fault & Joints

•Fold-- Wavy undulations (उतार चढ़ाव ) in the rock beds due to Earth movement are called "Fold".

~Elements of Folds-

Anticline & Syncline-

-An Anticline is an up-fold.

-A Syncline is a down-fold.

•Fault--Fault means fracture(दरार) along Which blocks of rock have been displaced relative to each other.

[अर्थात जब Rock bed‌ में Earth movement की वजह से दरार आ जाती है और वे एक-दूसरे से अलग/विस्थापित हो जाते हैं तो उसे Fault कहते हैं।]

~Some types of Fault--

:Normal Fault- Broken ends do not overlap.

:Reverse Fault- Broken ends overlap.

:Trans current Fault- Broken ends move away in the same level.

It is caused by Tensional & Compressional forces.

•Joints-- Joints mean Fracture with no relative displacement between Block of Rock.

[जब Rock bed में Earth movement की वजह से दरार आ जाती है लेकिन वे एक-दूसरे से अलग नहीं होते, उसे Joints कहते हैं।]

it may be vertical, inclined or horizontal .

•Sill-- A Sill is a sheet like Igneous body which runs parallel to the bedding planes of pre existing strata.

•Dyke-- A dyke is a wall like Igneous body that cuts across the strata of the pre existing rocks. Dykes are often vertical or steeply inclined.

Sills are commonly made up of Dolerites & Basalt

they burn surrounding coal & make it hard.

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