Page:Africa by Élisée Reclus, Volume 3.djvu/55

 TOPOGRAPHY OF THE AZORES. 37 Thermal springs and vapour jets are numerous in other parts of the island, where they are disposed in a line running from north-west to south-east, that is, in the same direction as the axis of the archipelago itself. San-Miguel also abounds most in lakes, formerly craters which vomited burning scoriae, and are now filled with rain water. One of these occupies an oval depression immediately to the west of the Yal das Furnas, while a neighbouring basin, 3 miles round, with a depth of over 100 feet, was completely filled with ashes during the eruption of 1563, and is now known as the Lngoa Secca, or "Dry Lake." Six miles farther on is the lagoon Do Cotigro, filling a deep crater, with steep walls rising 100 feet above the water. Beyond it is the alpine Lagoa do Fogo, or " Fiery Lake," which has replaced a burning crater opened in 1563. On this occasion the Volcao, or " Volcano," a lofty mountain so called in a pre-eminent sense, disappeared altogether, being transformed to a mass of ashes and pumice, which were strewn over the island and for hundreds of miles over the surrounding ocean. Some of the volcanic dust was even said to have been wafted by the wind as far as Portugal. The western extremity of San-Miguel is almost entirely occupied by a circular crater, with a surprisingly regular outer rim 9 miles in circumference, and cut up at intervals by the action of the rains. The vast amphitheatre is dominated by several volcanoes, culminating south-eastwards in the Pico da Cruz, 2,830 feet high. The sheet of water flooding the great crater lies at an altitude of little over 1,000 feet above the sea, and according to tradition this chasm was opened in 1444, the very year when the first settlers were landed on the island by Cabral. This statement, however, has not been confirmed by a geological study of the crater, which has also received from the popular fancy the name of the Caldeira das Sete Cidades, or " Cauldron of the Seven Cities." Here were doubtless supposed to have been submerged the " Seven Cities " of Antilia, founded by the seven legendary bishops said to have fled from Portugal at the time of the Moorish invasion. The lake, which has an extreme depth of over 350 feet, is disposed in two distinct basins, the Lngoa Grande in the north, separated by a scarcely emerged tongue of land from the southern Lagoa AzuJ, or "Azure Lake." Each of the two volcanoes lying a little farther south has also flooded craters. Within the historic period some submarine volcanoes have risen close to the coast in the vicinity of the Sete Cidades. The regular crater facing the port of Yillaf ranca, on the south side of the island, is of unknown date. The first eruption witnessed in the open sea occurred in 1638, when a column of ashes was thrown up to the south-west of Cape Ferraria, a blackish cone at the same time slowly rising above the water ; but in a few months the new island was swept away by the winter storms. In 1811, however, another appeared to the south-west of the same spot. This was the famous Sahn'na, so named from the British frigate which witnessed the eruption, during which jets of scoria) and ashes rose at intervals to a height of over 680 feet above the cliffs of the neighbouring coast. A cloud of vapours revolved round about this column of debris like a vast wheel, and on the fourth day the first dark outline of Sabrina rose to the surface. In three