Natural Wonders - Iceland - page 729

GEOLOGICALLY SPEAKING
Everywhere you go in Iceland you'll be bombarded with geological jargon to describe the
landscape. The following terms will let you one-up the other geological neophytes.
Basalt The most common type of solidified lava. This hard, dark, dense volcanic rock
often solidifies into hexagonal columns.
Igneous A rock formed by solidifying magma or lava.
Moraine A ridge of boulders, clay and sand carried and deposited by a glacier.
Obsidian Black, glassy rock formed by the rapid solidification of lava without crystal-
lisation.
Rhyolite Light-coloured, fine-grained volcanic rock similar to granite in composition.
Scoria Porous volcanic gravel that has cooled rapidly while moving, creating a glassy
surface with iron-rich crystals that give it a glittery appearance.
Tephra Solid matter ejected into the air by an erupting volcano.
Geysers, Springs & Fumaroles
Iceland's Great Geysir gave its name to the world's spouting hot springs (it comes from
the Icelandic for 'to gush'). It was once very active, frequently blowing water to a height of
80m, but earthquakes have altered the pressures inside its plumbing system and today it is
far quieter. Strokkur now demonstrates the effect admirably, blasting a steaming column
into the air every five to 10 minutes.
Geysers are reasonably rare phenomena, with only around 1000 existing on earth.
However, in Iceland water that has percolated down through the rock and been super-
heated by magma can emerge on the surface in various other exciting ways. Some of it
boils into hot springs, pools and rivers - you'll find natural hot water sources all around
Iceland, including the springs at Landmannalaugar, the river at Hveragerði and the warm
blue-white pool in the bottom of the Víti Crater. Icelanders have long harnessed these
soothing gifts of nature, turning them into geothermal swimming pools and spas, the
smartest of which are Mývatn Nature Baths and the Blue Lagoon. These latter two are not,
however, natural hot springs - they are manmade lagoons fed by the water output of the
nearby geothermal power plants.