When rocks undergo plastic deformation, the resulting shapes might be bent or folded. Rock undergoes the process of folding when it is squeezed, as it is along the boundary of plates that are colliding with one another. Folds that have been turned down are represented on the map by anticlines, whereas folds that have been turned up are represented by synclines.
Both anticlines and synclines are examples of geological formations; more specifically, they are examples of folds in rock material. They give surface manifestation in the form of linear ridges (anticlines), as well as valleys (synclines). The limbs of the fold are the sides of the folded object. Each fold has what is known as an axial plane, which is an imaginary plane that runs along the length of the fold and divides it in two.
The result of moderate compression is the formation of symmetrical or open folds, characterized by axial planes that are nearly vertical and limbs that dip gently at approximately the same inclination. Near the borders of mountain ranges, where tectonic activity is relatively quiet, you can find folds that are symmetrical in nature. It’s possible that an inverted fold will happen if the compression is more intense in one particular direction.
Extremely directed pressure can cause the fold to recline, producing a fold whose axial plane is nearly horizontal to the surface. This is known as a reclined fold. There are occasions when the length of the folds is angled in such a way that creates plunging folds. The Appalachian mountains, which can be found in the Ridge and Valley physiographic province of North America, are often considered to be one of the best examples of folded topography.
Surface faulting is likely to take place if massive stresses accumulate and push big, undamaged rock masses over the limits of their yielding capacity. A fracture along which movement may be observed is known as a fault. The term “fault plane” refers to the plane that extends into the earth and along which slippage occurs. The angle that the fault plane creates from the horizontal is referred to as the fault dip. The direction that the fault extends in on the map is referred to as the strike, and it is measured in relation to true north.
The footwall and the hanging wall are the two types of walls that are typically distinguished. The hanging wall can move either horizontally or vertically in relation to the footwall, or it can move in both directions simultaneously. We determine the location of the footwall and the hanging wall in relation to the fault plane. The foot wall is located below the fault plane, whereas the hanging wall can be found above it. The sloping side of a block that is exposed is referred to as the fault scarp. The path that the fault takes over the surface is known as the fault line.
On the surface, faults can be followed for thousands of kilometers, and at depths of tens of kilometers, they go even deeper. Earthquakes are caused when large rock masses suddenly slide past one another, which sends forth shock waves that are felt on the surface of the earth.