A concordant coastline comprises bands of different rock types that run parallel to the shore. The rock types are typically of alternating resistance, so that the coastline forms distinctive landforms, such as coves. A discordant coastline comprises rock types of alternating resistance that run perpendicular to the shore, creating distinctive landforms when the rocks are eroded by ocean waves. Less resistant rocks erode faster, creating inlets or bays; more resistant rocks erode more slowly, remaining as headlands or outcroppings.
Concordant flows at different points in a river system have the same recurrence interval, or the same frequency of occurrence. The term is most often applied to floodflows.