The main island, Grande-Terre (or Maore), geologically the oldest of the Comoro Islands, is long and wide, and its highest point is Mount Benara, at above sea level. Because of the volcanic rock, the soil is relatively rich in some areas. A coral reef encircling much of the island ensures protection for ships and a habitat for fish. Dzaoudzi was the capital of Mayotte (and earlier the capital of all the colonial Comoros) until 1977, when the capital was relocated to Mamoudzou on the main island of Grande-Terre. It is situated on Petite-Terre (or Pamanzi), which at is the largest of several islets adjacent to Maore.