top of page

Crystal Bay, Ascension Island, Saint Helena, Ascension and Tristan da Cunha


   Located close to the Mid-Atlantic Ridge, and nearly halfway between Africa and the horn of South America, Ascension is a volcanic island, a fact clearly reflected in this sand sample: polished black-gray grains of basalt; reddish ash (scoria); yellowish-green crystals of olivine, and shiny black obsidian. The abundance of olivine crystals lends the bay its name. Hints of the marine organisms living in the coast’s wave-pounded shallows are also present in this sand. A worn brownish-purple sea urchin spine lies near center, cross-sections revealing
the concentric interior structure of the spines are seen at 7 and 9 o’clock. The black and white shard in the upper right is a fragment
of snail shell. The island’s coastlines are constantly hammered by the waves that serve to round and polish these grains.

TCCON station AE.jpg

courtesy of the CIA World Factbook

bottom of page