Ash, Steam and Lava
The largest volcano in our solar system, Olympus Mons, is found in the Tharsis region on Mars. Olympus Mons (right) would cover the whole state of Washington and is 3 times higher than Mount Everest on Earth.
Olympus Mons may be the grandest volcano in the solar system, but it appears to have been dead for at least hundreds of millions of years.
Io's volcanoes almost constantly spew forth sulfurous gasses that create a giant ring of heated gases around Jupiter. As Io (below) moves around Jupiter it travels through the hot gases and gives off magnetized "Alfven waves" that cause radio emissions so powerful they can be heard as static on the loudspeakers of Ham (amateur) radios on Earth.
|Above is a close up of the area in the red square showing one of Io's volcanoes erupting.|
Elysium Planitia is the second largest volcanic region on Mars. It is 1,700 by 2,400 km in size and is located on an uplift dome. The 3 large volcanoes, Hecates Tholus, Albor Tholus, and Elysium Mons, are smaller than those found in Tharsis but are still quite large. Elysium Mons is the largest volcano in this region, measuring 700 km across and rising 13 km above the surrounding plains.
The volcanoes of the Cascade Mountain Range dividing Washington State and continuing into California are mostly dormant. Washington has a number of volcanoes with some that are still active. Mt. Rainier has had steam plumes and mudslides within the last 100 years. Mt. St. Helens erupted in May, 1980, and caused major changes in the landscape of the area.
We get the word "volcano" from the name of an island near Sicily in the Mediterranean Sea. The term volcano now refers to an opening (vent) on the Earth's surface where lava and hot gases are released. Click image or here to find out more about volcanoes (go on to the next page).
Here are some basic terms used in the tour. Find more geology terms in the Glossary.
- Fragments of less than 2 millimeters in diameter of lava or rock blasted into the air by volcanic explosions.
- Volcanic rock caused by partial melting of the Earth's crust.
- A large volcanic depression, commonly circular or elliptical when seen from above, caused by a volcano collapsing into itself.
- Cinder Cone
- A circular or oval cone made up of small fragments of lava from a single vent that have been blown into the air, cooled and fallen around the vent.
- Composite Volcano
- A steep-sided volcano composed of many layers of volcanic rocks, usually made from high-viscosity (thick like honey) lava, ash and rock debris (broken pieces).
- A steep-sided mound that forms when viscous (thick like honey) lava piles up near a volcanic vent (opening at the surface).
- A vent that releases volcanic gases and steam.
- A mixture of water and rock debris that forms on the slopes of a volcano. Also known as a mudflow or debris flow. The term comes from Indonesia.
- A light-colored volcanic rock containing lots of bubbles from trapped gases. This rock can sometimes float on water.
- Pyroclastic Flow
- A hot, fast moving and high-density (thick like wet concrete) mixture of ash, pumice, rock fragments and gas formed during explosive eruptions.
- Shield Volcano
- A volcano shaped like a bowl in the middle with long gentle slopes made by basaltic lava flows.
- An opening at the surface where magma, gas and steam erupt.
- A vent at the surface where magma, gas and steam erupt. Also, the landform constructed by volcanic material.
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