Wednesday, 8 April 2015

Label The Parts Of A Volcano

Volcanoes come in a variety of types.


Volcanoes capture everyone's imagination: Whether mountainous or simply a collection of vents, they exist where lava from the Earth's molten innards escapes to the surface, often explosively. Labeling a picture or model of such geologic landforms can be easy and informative.


Instructions


1. Look for the volcano's main vent or opening. On mountainous volcanoes and some other types, this is called the crater, where magma--molten rock--emerges, sometimes explosively. Craters usually crown the most familiar-looking volcanoes, such as stratovolcanoes. Most of the big cones of the Cascades, like Mount Rainier and Mount Hood, are stratovolcanoes. Summit craters will also be found on shield volcanoes. These mountains, which may be of such great size and subtle slopes as to be difficult to distinguish up close, include the biggest active volcanoes in the world, Hawaii's Mauna Loa among them.


Some craters and vents may not be associated with a mountain, as in the volcanic openings producing the sheets of lava called flood basalts. These would require little more than a labeling of their surface vents, which may be numerous, unless you were also identifying the subterranean network of magma chambers and pathways.


2. Label a caldera if one exists. This formation is the collapsed summit of a volcano and will be located in the same area as the main crater. But a caldera, which may form when eruptions empty the magma chambers below, will occupy more space than the former crater. The misnamed Crater Lake in Oregon's southern Cascades is a deep, intensely blue body of water occupying the caldera of Mount Mazama, which exploded and collapsed around 7,000 years ago.


3. Identify the flanks of a mountainous volcano, which are the mountain's slopes. For a technical diagram, you might also be labeling the volcano's innards: its layers of volcanic material (which may range widely in composition) or the layout of its lava shafts, for example. You may also be labeling cinder cones on the flanks of bigger stratovolcanoes or shield volcanoes. These are small, conical volcanoes often fed by basaltic lava, and on a larger peak mark the location of side vents.


4. Label other environmental features for a very detailed or specific representation of a volcano. For example, if identifying features on one of the large stratovolcanoes, such as Mount Hood or Mount Fuji, you might also label drainages, which for such cones are often radial in form--i.e., streams spilling from all directions from the central height. Also note the glaciers that often ring the highest of such volcanoes; Mount Rainier in the Washington Cascades, for example, has 25 glaciers on its crest.

Tags: also labeling, magma chambers, might also, Mount Hood, Mount Rainier, shield volcanoes, shield volcanoes These