Final answer:
The main difference between concordant and discordant coastlines is the direction of the rock layers in relation to the coastline. Concordant coastlines have rock layers running parallel to the shore, while discordant coastlines have rock layers perpendicular to the shore, often resulting in more varied coastal landforms.
Step-by-step explanation:
The difference between concordant coastlines and discordant coastlines involves the arrangement of rock strata in relation to the coastline and the resulting landforms. Concordant coastlines, also known as Pacific-type coastlines, occur when layers of rock run parallel to the shore.
This alignment can create long, smooth coastlines with few indents such as coves or bays. Discordant coastlines, on the other hand, also known as Atlantic-type coastlines, form where rock layers are perpendicular to the shore. This geological setup can lead to headlands and bays, as softer rocks erode faster, leaving harder rocks protruding as headlands.
The direction of the coastline in relation to convergent and divergent tectonic boundaries can also influence coastal features. Tectonic movements, like Continent-Continent Convergence (CCC), Ocean-Ocean Convergence (OOC), Continent-Ocean Convergence (COC), Continent-Continent Divergence (CCD), and Ocean-Ocean Divergence (OOD) can modify coastlines over time, forming new landscapes.