GEOLOGY

EARTH SCIENCE

VOLCANOES

Question [CLICK ON ANY CHOICE TO KNOW THE RIGHT ANSWER]
Shield volcanoes have ____
A
pyroclastic material
B
gently sloping sides
C
high, wide, steep sides
D
clusters
Explanation: 

Detailed explanation-1: -Shield volcanoes, on the other hand, have gentle slopes that are less than 10° and erupt more fluid lavas called basalt. When a shield volcano erupts, the basalt can flow great distances away from the vent to produce broad, gentle slopes.

Detailed explanation-2: -Shield volcanoes, the third type of volcano, are built almost entirely of fluid lava flows. Flow after flow pours out in all directions from a central summit vent, or group of vents, building a broad, gently sloping cone of flat, domical shape, with a profile much like that of a warrior’s shield.

Detailed explanation-3: -The gentle slopes are the result of the low lava viscosity, allowing lavas to flow fast and far. The lava flows (pahoehoe and aa) commonly initiate their path from flank vents and fissures rather than from the summit. These flank vents are the result of the widening and / or subsidence of the volcano.

Detailed explanation-4: -Shield volcanoes feature a gentle (usually 2° to 3°) slope that gradually steepens with elevation (reaching approximately 10°) before flattening near the summit, forming an overall upwardly convex shape. In height they are typically about one twentieth their width.

Detailed explanation-5: -Shield volcanoes have the following characteristics: Basaltic magma, which is high in temperature, very low on silica and with low gas content. This type of magma produces fluid lava with very little explosive activity. Basic lava, which is non-acidic and very runny.

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