GENERAL GEOLOGY

Dip And Strike

How to determine Dip and Strike

The beds of most sedimentary rocks generally get deposited on flat or very gently inclined surfaces. But when we find strata with a great thickness distinctly tilted into an inclined position, it comes in the mind that the beds have been tilted during earth movements that occurred after their deposition. The attitude of an inclined bed has got two important components as

  1.  Dip
  2. Strike

The object of measuring dip and strike of rock is to obtain information on their three-dimensional position.

 1. Dip

The angle of inclination of rock bed with the horizontal plane is called “dip”. It is measured on a vertical plane lying at the right angle to the strike of the bedding. The dip amount dip angle varies from ‘0º’ to ’90º’ according to the position of the bed.

Types of Dip

There are two types of dip

  • True Dip–  It is defined as the maximum angle of dip on a rock bed. It is measured in the direction at right angle to the strike
  • Apparent Dip– A dip measured in any other direction other than that of the true dip. An apparent dip will always have a value less than the true dip. Along the strike direction, however, the dip will be zero.

Dip and Strike of an inclined bed.

2. Strike

It is a geographic direction given by a line of intersection of a horizontal plane with a bedding plane of a layer of rock or “strike” can be defined as the direction of a line formed by the intersection of bedding plane and horizontal plane. The strike is always at the right angle to the true dip direction. The strike of the bed is independent of its amount of Dip.

In structural Geology Dip and Strike are very important they are used for-

  • For the determination of the younger bed or formation at the outcrop.
  •  In classification and nomenclature of fold, faults, joints, and unconformities, the nature of dip and strike is very useful.

 

 

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