Ridge and runnel systems are formed due to the interaction of tides, currents, sediments and the beach topography. They only form on beaches with a shallow gradient. They form as a simple drainage route for tides. Water flows in and out via the runnel.

How is a bay bar formed?

A bay bar is very similar to a spit. It is a ridge of sand or single that joins two headlands either side of a bay. It is formed due to longshore drift transporting sediment along the coastline.

How are Tombolos formed geography?

A tombolo is formed when a spit connects the mainland coast to an island. ... This causes material to be deposited in a long thin strip that is not attached to the coast and is known as a spit. If this feature moves in the direction of island and connects it to the mainland then it becomes a tombolo.