Iceland is an elevated plateau about two thousand feet high, with a narrow marginal habitable region sloping gently to the sea. The elevated plateau is the seat of every species of volcanic action, viz., lava-eruptions, solfataras, mud-volcanoes, hot springs, and geysers.

These last exist in great numbers; more than one hundred are found in a circle of two miles diameter. One of these, the Great Geyser, has long attracted attention.

The Great Geyser is a basin or pool fifty-six feet in diameter, on the top of a mound thirty feet high. From the bottom of the basin