Describe speciation of the galapagos island finches in term of geographic isolation

The galapagos archipelago are a series of islands which are separated by a considerable distance of ocean between them due to which reason the finches found on them are genetically isolated from one another, that is they are incapable of mating due to the distance. So they have evolved in isolation based on the environment of the island they inhabit such that they have over time evolved into different breeds.