Barrier islands form in three ways. They can form from spits, from drowned dune ridges or from sand bars. Longshore drift is the movement of sand parallel to the shore caused by the angle of the waves breaking on the beach. When a storm such as a hurricane digs an inlet through the spit a barrier island is formed. Barrier islands are a specific type of island that lie parallel to the coastline of a larger mainland. They are separated from shore by a bay, lagoon or sound and because of where they are situated, they protect the coast from being directly impacted by storm waves or winds.
incomplete dominance is inheritance in which one allele for a specific trait is not completely expressed over its paired allele. this results in a third phenotype in which the physical trait is a combination of both alleles.
