Ascension Island
Today we spent a full day at Ascension Island, walking in the little settlement of Georgetown and touring the island by minibus. Ascension Island is a volcano 4 km. high, which rises from the seabed to a height of 859 m. The island sits about 100 km. west of the axis of the Mid-Atlantic Ridge and is thus on the South American Plate and is moving slowly to the west. The summit of the island is Green Mountain on which an island effect cloud is nearly always present, as it was for much of the day today. This cloud produces an annual rainfall of 680 mm. at an altitude of 660 m. compared with 130 mm. at the coast. Looking down from the lush gardens of Green Mountain to the moonscape of the rather fresh volcanic flows of the coastal plain (pictured) we see one of the many contrasts of the island. In 1817 a farm was established on Green Mountain to provide fresh produce for the island’s inhabitants and a supply line built in 1831 brought water from the mountain to Georgetown. The arid lower parts of the island are covered with cinder cones and lava flows which display the entire spectrum of lava forms and compositions. We examined volcanic bombs which intrigued Charles Darwin during his visit to Ascension in 1836. He rightly hypothesized that they were formed as small blobs of molten lava flew spinning through the air during eruptions of the volcano. Today Ascension is home to an RAF Base and a U.S. Air Force Base, primarily employed tracking satellites and “space junk” orbiting the earth near the equator. The small number of military personnel on both bases are supported by a larger number of contract employees from St. Helena, some of whom have lived on Ascension for decades. Other government contractors employ most of the rest of the population of about 1000. This evening we sailed south on our journey to the next of the Atlantic Ridge volcanos, the island of St. Helena.
Today we spent a full day at Ascension Island, walking in the little settlement of Georgetown and touring the island by minibus. Ascension Island is a volcano 4 km. high, which rises from the seabed to a height of 859 m. The island sits about 100 km. west of the axis of the Mid-Atlantic Ridge and is thus on the South American Plate and is moving slowly to the west. The summit of the island is Green Mountain on which an island effect cloud is nearly always present, as it was for much of the day today. This cloud produces an annual rainfall of 680 mm. at an altitude of 660 m. compared with 130 mm. at the coast. Looking down from the lush gardens of Green Mountain to the moonscape of the rather fresh volcanic flows of the coastal plain (pictured) we see one of the many contrasts of the island. In 1817 a farm was established on Green Mountain to provide fresh produce for the island’s inhabitants and a supply line built in 1831 brought water from the mountain to Georgetown. The arid lower parts of the island are covered with cinder cones and lava flows which display the entire spectrum of lava forms and compositions. We examined volcanic bombs which intrigued Charles Darwin during his visit to Ascension in 1836. He rightly hypothesized that they were formed as small blobs of molten lava flew spinning through the air during eruptions of the volcano. Today Ascension is home to an RAF Base and a U.S. Air Force Base, primarily employed tracking satellites and “space junk” orbiting the earth near the equator. The small number of military personnel on both bases are supported by a larger number of contract employees from St. Helena, some of whom have lived on Ascension for decades. Other government contractors employ most of the rest of the population of about 1000. This evening we sailed south on our journey to the next of the Atlantic Ridge volcanos, the island of St. Helena.
