Igneous landforms and structures

Question 0

Strato-volcano or Composite volcano rock type? Characteristics? Example location?

Answer 0

andesite; Forms a stereotypical cone-shape volcano with slopes that range from 30 to 60 degrees of steepness. Lavas flow less than a few miles from vents and contain weak layers of tephra. This layering makes the volcano structurally weak and prone to dangerous avalanches and mudflows. Associated with the largest avalanches on Earth’s land areas. Mt Rainier

Question 1

Shield volcano rock type? characteristics? example location?

Answer 1

Rock type basalt; These volcanoes erupt from fissures and vents and create slopes of only a few degrees in steepness (forms a topographic profile similar to a shield laying on the ground ). Lavas flow for tens of miles ad create the highest mountains on Earth.;example location Hawaii

Question 2

Maar rock type? characteristics? example location?

Answer 2

no lava flows so no mineral; When a source of limited magma rises, it may contact groundwater. The water will expand rapidly in a steam explosion that can blast a crater up to a mile in diameter and hundreds of feet deep. Since the magma is limited, lava flows do not follow the explosion events.; Hole-in-the-Ground, southeast Oregon

Question 3

What is “good” about volcanoes?

Answer 3

Volcano eruptions and intrusions have created the Earth’s crust where we live. Volcanoes release ozone which gives Earth its protective atmosphere. Volcanoes drive heat from Earth’s interior to Earth’s surface and maintain carbon dioxide in Earth’s atmosphere to keep the surface warm to support life through the
“Greenhouse Effect”!

Question 4

Caldera rock type? characteristics? example location?

Answer 4

rhyolite; extremely violent eruptions blasts most of the lava out of the magma chamber, after which, much of the volcano collapses back into the empty magma chamber. Few lava flows exist because the lava usually is too thick to flow from the vent. Yellowstone

Question 5

Cinder cone rock type? characteristics? example locations?

Answer 5

andesite; This volcano type forms from a limited magma source often located along transform or divergent zone faults). Most of these volcanoes attain less than few thousand feet in elevation. Because the lava usually is too thick to flow from the vent.; Black Butte, Bend area, Oregon

Question 6

Lava Dome rock type? characteristics? example location?

Answer 6

andesite; Domes often form near the beginning or end of an eruptive cycle. Very thick lava can plug or seal a vent. Great pressures below the plug can slowly push this plug upward *like squeezing toothpaste out of a tube), which extrudes as a lava dome on the surface. If pressures get to high, a small or large eruption may remove the plug. Other domes can follow, and can grow to 100’s to a few 1,000’s of feet high.; Mt St. Helens

Question 7

flood lava or plateau lava rock type; characteristics;example location?

Answer 7

rock type basalt. characteristics These flat-surface volcanoes erupt from rift zone fissures and flood over the landscape to bury the original topography in the surrounding region. Lava flows can travel hundreds of miles and create the largest volcanoes (by surface area) on Earth. Example location Columbia Plateau