What is the Difference Between Syncline Anticline and Monocline

The main difference between syncline anticline and monocline is that in syncline, the strata slope upwards from the crest, and in anticline, the strata slope downwards from the crest, whereas in monocline, the strata are either uniformly dipping or horizontal.

Syncline, anticline and monocline are three terms that are useful in describing the tough or fold of stratified rocks. These terms, thus, define the arrangement of strata in the stratified rock.

Key Areas Covered

1. What is Syncline 
     – Definition, Features
2. What is Anticline 
     – Definition, Features
3. What is Monocline
     – Definition, Features
4. What is the Difference Between Syncline Anticline and Monocline
     – Comparison of Key Differences

Key Terms

Anticline, Syncline, Monocline

What is Syncline

A syncline is a fold with young layers of rock closer to the centre of the structure. Anticline structure is the opposite of this syncline structure. A large syncline with superimposed smaller folds is called a synclinorium. The synclines are typically downward fold (we call it a synform), but we can find the strata slope upwards from the crest.

Figure 1: Appearance of a Syncline

If we are using a geographic map, we can recognize synclines as a sequence of rock layers. Here, the youngest layers are at or near the centre of the fold (or hinge), and there is a reverse sequence of the same rock layers on the opposite side of the hinge. Moreover, we can name the pattern as basin if the fold pattern in the structure is circular or elongated. These folds usually form when crustal deformations occur as the result of compression that accompanies orogenic mountain building.

What is Anticline

Anticline is a type of fold that has an arch-like shape. This pattern has the oldest layers of rock at the core, and the fold is exactly opposite to that of a syncline pattern. Generally, an anticline is convex up, and the hinge is the location at which the curvature is highest. Here, limbs are the sides of the fold that dip away from the hinge.

Figure 2: Anticline Structure

Moreover, we can recognize the anticline pattern as a sequence of rock layers that become progressively older toward the centre of the fold. 

What is Monocline

Monocline is a type of fold that has a step-like pattern. It is a step-like fold in rock strata consisting of a zone of steeper dip within an otherwise horizontal or gently-dipping sequence.

Figure 3: A Monocline Landscape

There are different ways that a monocline may form. For example, it can form via differential compaction over an underlying structure which is particularly a large fault at the edge of a basin due to the greater compactibility of the basin fill, and the amplitude of the fold will die out gradually upwards. Moreover, a fold can form via mild reactivation of an earlier extensional fault during a phase of inversion, causing folding in the overlying sequence.

Difference Between Syncline Anticline and Monocline

Definition

A syncline is a fold with young layers of rock closer to the centre of the structure. Anticline is a type of fold that is an arch-like shape, while monocline is a type of fold that has a step-like pattern.

Structure

In syncline, the strata slope upwards from the crest, while in anticline, the strata slope downwards from the crest. However, in monocline, the strata are either uniformly dipping or horizontal.

Pattern

Syncline has a trench-like pattern, and anticline has an arch-like pattern while monocline has a step-like pattern. 

Conclusion

The terms syncline, anticline and monocline are useful in describing the tough or fold of stratified rocks. The main difference between syncline anticline and monocline is that in syncline the strata slope upwards the form the crest and in anticline the strata slope downwards from the crest whereas in monocline the strata are either uniformly dipping or horizontal.

Reference:

1. “Syncline.” Wikipedia, Wikimedia Foundation, 30 Mar. 2020, Available here.
2. “Anticline.” Wikipedia, Wikimedia Foundation, 25 Jan. 2020, Available here.
3. “Monocline.” Wikipedia, Wikimedia Foundation, 7 Apr. 2020, Available here.

Image Courtesy:

1. “Rainbow Basin” By Wilson44691 at English Wikipedia – Photograph taken by Mark A. Wilson (Department of Geology, The College of Wooster) (Public Domain) via Commons Wikimedia
2. “Anticline (PSF)-vector” By Original image by Pearson Scott Foresman, Converted to SVG by Offnfopt – Derivative work of File:Anticline (PSF).png (Public Domain) via Commons Wikimedia
3. “Grandview-Phantom Monocline” By Jstuby at en.wikipedia – Own work Transferred from en.wikipedia (Public Domain) via Commons Wikimedia