set:volcanoes // series: types of lava flow // picture: CINDER CONE
TYPES OF LAVA FLOW
Cinder cones like this one are characteristic of mildly explosive, small-scale eruptions of basaltic or andesitic lava called strombolian eruptions (after the volcano Stromboli in the Aeolian Islands north of Sicily). No lava flows are formed in a typical strombolian eruption. Instead, a burst of incandescent blobs of vesicular lava is ejected into the air, together with finer ash. The fragments of magma remain in the air long enough to solidify before they hit the ground. The main product of such eruptions, therefore, is not a river of molten lava but a cone of loose black clinkers called scoria. The other name for a cinder cone is scoria cone. Seen in daylight, a strombolian eruption is unimpressive: just a bang or brief roar, a cloud of ash and cinders, and a clattering sound as they hit the ground. At night, however, you see a spectacular firework show as the glowing scoria surge up into the air and fall back down again along parabolic trajectories (see picture), building up the ramparts of the cinder cone. Cinder cones can be seen in the Eifel region of Germany, in the Massif Central of France (the Chaine des Puys consists of a row of well preserved scoria cones) and in islands such as Tenerife. As they consist of unconsolidated material, cinder ones are ephemeral and rarely survive more than a few thousand years.
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