{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

DYNAM EARTH FINAL REVIEW

DYNAM EARTH FINAL REVIEW - Chapter 9 Volcanoes Made in...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 9: Volcanoes Made in Terra Hades…Volcanic Products Lava Flows Pyroclastic Debris Volcanic Gas Lava Flows The ability of lava to flow depends on its viscosity The more viscous a substance is the slower it flows o Water has a low viscosity o Honey has a high viscosity The more silica the lava contains the grater its viscosity 3 types of lava flows Highly viscous flow o Dome like shape (as it emerges) o Travels little distance Viscous Flow o Thick flows o Travels some distance
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Fluid Flow o Thin flows o Travels great distance 2 types of eruptions Explosive eruption (gray eruption) o Violent eruption in which material is primarily in the form of pyroclastic debris Effusive eruption (red eruption) o More benign eruption in which material is ejected in the form of flowing lava *The more viscous a lava the more explosive the eruption The more viscous the lava the more gas is trapped As bubbles move from high to low pressure, their volume increases Gas expands as magma rises and explodes the lava at the top Greater the gas content, more explosive the eruption Volcano Geomorphology - shape and structure of volcano Controlling Factors o Type of eruption o Type of flow
Background image of page 2
*silica content - - viscosity - - gas content - - type of eruption *silica content - - viscosity - - type of flow Shield Volcanoes – broad, gently sloped cones Silica content - low Viscosity – low Gas Content – low Type of Flow – thin Type of Eruption – effusive lava flows o Ex. Mauna Loa, Hawaii Cinder Cones – steep sloped piles of volcanic debris and some lava flows Silica content – intermediate Viscosity – intermediate Gas content – intermediate Type of Flow – thin Type of Eruption – very explosive at vent; effusive lava flows o Ex. Cinder Cone, Arizona Stratovolcano (composite volcano) – very large cone- shaped mountaint Silica content – high Viscosity – high
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Gas content – high Type of flow – thick, dome Type of eruption – explosive pyroclastic o Ex. Mount Rainier, Washington State Alternating eruptions of pyroclastic material and effusive lava flows forms a “stratified” volcano Steep-sided stratovolcanoes are prone to landsliding because of the alternating layers of hard rock atop loose sediment Typical Volcano Crater – opening at the top Summit vent – lava vent at the top Flank vent – vent on the side Magma Chamber – magma stored below Pahoehoe Flows – ropy surface texture Aa Flows – rubbly flow with jumbled angular pieces Pillows – blob like pieces formed under water 66-76% silica – silicic intrusive – granite
Background image of page 4
extrusive - rhyolite 52-66% silica – intermediate intrusive – diorite extrusive - andesite 45-52% silica – mafic intrusive – gabbro extrusive – basalt Pyroclastic explosion products
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full Document Right Arrow Icon
Image of page 6
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}