Question

Types of Structural Geology
 Dip & Strike Measurement with example

Answer 1

Structural geology is the one which is concerned with the study of factors which causes various secondary structures  of rock . It studies the three dimensional distribution of rocks. The deformation of rock is due to a variety of processes like fold, fracture, faults etc.

The 3 main types of structural geology are- fracture, fold and faults. A fold is created on the rock by the horizontal compression of rock layers. Thus creates a bend, on the stratified rock. In fold, both anticlines and synclines are there. These are up folds and down folds respectively. A fracture is any seperation which causes the deformation. It is produced during stress. An example is the fragmentation of a rock into pieces. Fault is a type of fracture where fracture is developed in between two rock blocks. As a result, the two blocks slightly move apart, with the release of energy. This energy is the cause of earthquakes.  

The dip and strike measurements measures the orientation of rock surfaces. The strike measures the orientation of horizontal lines and the dip measures the angle between horizontal line and surface of rock. Both dip and strike are measured using the Brunton compass.

While measuring the strike, the compass is placed on rock surface in such a way that the bottom edge of the compass is flat against the rock. Next, the compass is oriented with the bubble of compass fixed at the centre, while keeping the bottom edge of compass fixed. The value is shown on either end of the needle.

The dip is measured with the same instrument like the strike being measured, but with a slight change. First, the compass is placed on the surface to be measured ,with fixing its lower edge against the plane. Now it points the direction of the dip. The clinometer is another part of the compass itself, which is used here to measure the dip. The liver of the compass is adjusted to make the air bubble to be in the clinometer level. The reading on the scale directly gives the value of dip.