2B.2A Concordant and Discordant
Geological Structure is responsible for the formation of concordant and discordant coasts.
Concordant
- Concordant coasts usually form where rock strata or folds run parallel to the coast.
- Some concordant coasts have long, narrow islands running parallel to the coastline.
- Concordant coasts are also known as dalmatian coasts, after the Dalmatian region of Croatia, or Pacific coasts, after the coastline of Chile in South America.
Discordant
- These are where rock strata or structures are aligned at an angle to the coastline.
- Discordant coasts have a crenellated pattern of projecting headlands and indented bays.
- Discordant coasts are also known as Atlantic coasts, after the Cork coastline in the Republic of Ireland.
Extra from Notes
- Geological structure is the characteristics and arrangement of rock units.
- Strata are different layers (or beds) of rock.
- A bedding plane is the interface between two sedimentary strata. Bonding between rocks either side of the plane is weaker than bonding within strata.
- Deformation is the degree of tilting of folding of rock.
- Dip is the angle of inclination of titled strata.
- Faulting is the fracturing of rock with movement from its original position.
- A joint is a fracture of rock without movement from the original position, e.g. caused by the shrinkage of igneous rock as it cools.