The southern part of the Mascarene plateau, also known as Southern Mascarene plateau (SMP), was formed by the Réunion volcanic hotspot along with the Chagos-Laccadive Ridge. The banks and shoals of the southern part of the Mascarene plateau were once volcanic islands, much like Mauritius and Réunion, which have now sunk or eroded to below sea level or, in the case of the Cargados Carajos, to low coral islands. The Saya de Malha Bank formed 35 million years ago, and the Nazareth Bank and the Cargados Carajos shoals formed later. Limestone banks found on the plateau are the remnants of coral reefs, indicating that the plateau was once a succession of islands. Some of the banks may have been islands as recently as 18,000-6,000 years ago, when sea levels were up to 130 meters lower during the most recent ice age. Mauritius formed 8-10 million years ago, and Rodrigues and Réunion formed around two million years ago. Piton de la Fournaise volcano on Réunion is one of the most active volcanoes in the world.