Answer:
Volcanic Landforms
Volcanic landforms are controlled by the geological processes that form them and act on them after they have formed. Thus, a given volcanic landform will be characteristic of the types of material it is made of, which in turn depends on the prior eruptive behavior of the volcano. Although later processes can modify the original landform, we should be able to find clues in the modified form that lead us to conclusions about the original formation process. Here we discuss the major volcanic landforms and how they are formed, and in some cases, later modified. Most of this material will be discussed with reference to slides shown in class that illustrate the essential features of each volcanic landform.
Stratovolcanoes (also called Composite Volcanoes)
Have steeper slopes than shield volcanoes, with slopes of 6 to 10o low on the flanks to 30o near the top.
The steep slope near the summit is due partly to thick, short viscous lava flows that do not travel far down slope from the vent.
Cinder Cones(also called Tephra Cones)
Cinder cones are small volume cones consisting predominantly of tephra that result from strombolian eruptions. They usually consist of basaltic to andesitic material.
Resurgent Domes
After the formation of a caldera by collapse, magma is sometimes re-injected into the area below the caldera. This can result in uplift of one or more areas within the caldera to form a resurgent dome. Two such resurgent domes formed in the Yellowstone caldera, as shown above.
Plateau Basalts or Flood Basalts
Plateau or Flood basalts are extremely large volume outpourings of low viscosity basaltic magma from fissure vents. The basalts spread huge areas of relatively low slope and build up plateaus.
Geysers, Fumaroles and Hot Springs
A fumarole is vent where gases, either from a magma body at depth, or steam from heated groundwater, emerges at the surface of the Earth. Since most magmatic gas is H2O vapor, and since heated groundwater will produce H2O vapor, fumaroles will only be visible if the water condenses. (H2O vapor is invisible, unless droplets of liquid water have condensed).
Hot Spots
Volcanism also occurs in areas that are not associated with plate boundaries, in the interior of plates. These are most commonly associated with what is called a hot spot. Hot spots appear to result from plumes of hot mantle material upwelling toward the surface, independent of the convection cells though to cause plate motion. Hot spots tend to be fixed in position, with the plates moving over the top. As the rising plume of hot mantle moves upward it begins to melt to produce magmas. These magmas then rise to the surface producing a volcano. But, as the plate carrying the volcano moves away from the position over the hot spot, volcanism ceases and new volcano forms in the position now over the hot spot. This tends to produce chains of volcanoes or seamounts (former volcanic islands that have eroded below sea level).
Explanation:
#CarryOnLearning
