THEMATIC VOLCANO PHOTO GALLERY:
- Basalt (basaltic lava) -
Basaltic columnar-jointed lava (Iceland).
Basalt is the usually hard and black volcanic rock formed from (liquid)
balsalitc lava. Balsaltic lava contains less than about 52 percent silica
(SiO2) by weight. Because of its low silica content,
it has a low viscosity (resistance to flow). Therefore, basaltic lava can
quickly and easily flow more than 20 km from a vent. The low viscosity
typically allows volcanic gases to escape without generating enormous
eruption columns, although basaltic lava fountains and fissure eruptions, however,
still can be hundreds of meters tall. Basaltic lava is erupted at temperatures
between 1100 to 1250°C.
Basaltic lava flows can be subdivided into two end-member structural types, according to their flow surfaces:
More about volcanic rocks (chemical and physical properties) can be found at a special page of the USGS.
Basaltic lava flows on Hawaii.
Before using text and photos of this page elsewhere please contact Tom Pfeiffer.
© Tom Pfeiffer, page set up on 12 April, 2004.