3. _In the Indian Ocean._--On the western border of the Indian Ocean there are a few volcanoes in Madagascar; in the Island of Bourbon; Mauritius; the Comoro Islands; and in Kerguelen Land on the south. There are also volcanoes on the western border of the Indian Ocean where the lofty peak of Kilima Ndjro, 18,000 feet, is volcanic. 4. _Over the Seas that Separate the Northern and the Southern Continents and in their Vicinity._--This is an especially active region of volcanoes. For the sake of convenience the continents of the world are sometimes divided into three pairs or double continents; namely, North and South America, connected by the Isthmus of Panama; Europe and Africa, connected by the Isthmus of Suez; and Australia and Asia, completely separated by a sunken isthmus, the summits of which form the Sunda Island chain. In the first of these regions we have the very active group of the West Indies, where there are ten volcanic islands. In the second pair of double continents we have the volcanoes of the Mediterranean and Red Seas, and their borders, such as Sicily, Vesuvius, and other parts of Italy, Spain, Germany, the Grecian Archipelago, Asia Minor, and extending eastward through the Caspian, Mt. Ararat, Demavend, on the south shores of the Caspian, Mt. Ararat, and some few others along the borders of the Red Sea. In the East Indies we find the most intense centre of volcanic activity in the world. Here there are some 200 volcanoes of which there are nearly fifty in Java alone, more than half of which are still active. There are nearly as many volcanoes in Sumatra, and many in the small islands near Borneo, the Philippines, etc. 5. _On the Borders of the Atlantic and Elsewhere._--It is an interesting fact that there are no volcanoes on the eastern borders of the Atlantic north of the West Indies Island chain. In the South Atlantic the only volcano on the borders is one of the Cameroons Mountains. In the Atlantic Ocean we have Iceland, the Azores, the Canaries, Cape Verde, Ascension, St. Helena, and Tristan d'Acunha. This curious distribution of the volcanoes of the world near the oceanic waters appears to be dependent rather on the very early shapes of the continents and the ocean beds than on their present shapes. CHAPTER XVII VOLCANOES OF THE GEOLOGICAL PAST The question is often asked whether the volcanic eruptions of the geological past were not much more violent and destructive than the volcanoes of the present time. Now, while this is a matter that properly belongs to the subject of geology, and will be treated at greater length in the Wonder Book on Geology, yet a short mention should be made of it here.