Geography and Geology


    The island of Floreana spans across an area that is approximately 12 km x 15 km and rises to a peak elevation of 640 m.  Floreana possesses some of the oldest lavas (1.5 million years) that are found on the volcanic Galapagos archipelago, making Floreana on the older islands.  It is covered with many young pyroclastic cones, which are produced when lava is thrown into the air explosively.  Floreana itself remains an active volcano and represents one extreme of the range of lava compositions encountered on the islands.   Basalts from active volcanic sites are distinctely more "alkalic" in composition as opposed to the more "theoleiitic" compositions produced by most volcanoes.  Floreana magmas are produced at shallower depths in th earth's mantle and by smaller extents of melting than in the rest of the Galapagos.  Moreover, Floreana is one of the few islands with a reliable fresh water supply--an artesian spring at the base of Cerro Olympus.

photograph by Charles F. Urbanowicz [2000].


Espanola albatross
Espanola is one of the smaller Galapagos Islands measuring 7 km x 14 km and reaching an elevation of about 200 m.  Espanola is the oldest Galapagos Island dating back 3.25 million years.  The island represents the northern two-thirds of a once larger volcano and appears to have been subjected to the same tectonic processes that have disrupted other islands of the Galapagos.  The low elevation of Espanola makes it dry and inhospitable to terrestrial life, though it is still a favorite spot for many seabird species.

Rosalind Cohen, NODC, NOAA