Beach ridges in West Africa show how changes in sediment supply affect coastal development. Minor ridges come from nearby sand sources like cliffs or the sea, while major ridges in Sierra Leone and Benin get sand from rivers and longshore drift. Early ridges had segmented barriers, but as estuaries filled up, a continuous drift system formed, leading to long beach ridges over 250 km long. Today, coastal sand transport determines how ridges form, whether sand stays near its source, moves to the ridge front, or drifts down the coast.