Seen from the sea, the Azores present a grandiose sight composed of high black or grey cliffs beaten ceaselessly by the Atlantic rollers. The Mid Atlantic Ridge marks a sort of weak point in the Earth’s surface, the focus of attention for geologists trying to explain Continental Drift theories. From Iceland in the Arctic north to Tristan da Cunha in the south Atlantic, all the islands on this chain are characterized by volcanic activity, and that includes the Azores. While most of the Azorean volcanoes are now extinct, subterranean forces still demonstrate their presence by occasional eruptions. Only fifty-five years ago the Capelinhos volcano in Faial dramatically altered that island’s west coastline, and in 1980 Terceira, Graciosa and São Jorge were hit by a severe quake which destroyed seventy per cent of Terceira’s capital, Angra do Heroísmo.
The Azores are, essentially of volcanic origin, each island showing the summit of an underwater volcano. Eruptions were still taking place in the 19th century and seismic vibrations on land or under the water are still frequent. In 1812, a small island, Sabrina, was thrown’ up to the west of São Miguel but disappeared a few weeks later.
The central part of São Miguel is of more recent origin than the two mountainous chains on each side of it (the Caldeira of Sete Cidades and the Caldeira of Lagoa do Fogo), the arm of sea which once divided them having been filled in by successive eruptions. Most of the rock forma-tions consist of lava, basalt and trachyte. On Santa Maria, however, limestone, rich in fossilized shellfish, is to be found embedded in the lava.
The archipelago’s volcanic origin explains the presence on the islands of so many extinct maters. The highest and most interesting is Pico, which gives its name to an island. Rising to 7,610 feet, snow covers it in winter; still slightly active, white vaporous fumes can sometimes be seen emerging.
Also worthy of interest, on the island of São Miguel are the Pico de Vara (3,624 feet) and two enormous valleys of volcanic debris, Fumes, with its boiling water springs, and Sete Cidades, with a diameter of 3 miles and at the bottom of which are two lakes. On the island of São Jorge is the Pico da Esperanga (3,497 feet) and on Terceira island the Pico de Santa- Barbara (3,500 feet) and the crater of Monte Brazil.
From the dark basalt rocks and now peaceful green craters to bubbling sulphurous mud-baths, the landscape everywhere proclaims its origins and incidentally attracts hordes of geologist to admire and study them.
