Download Ring of Fire – Around Pacific area, lots of volcanoes

Geo [Somewhat Colloquiallized] Term Sheet : Volcanoes/Dating PART 1+2
Ring of Fire – Around Pacific area, lots of volcanoes
Not a lotta volcanoes in Africa/mainland Asia
Magma generated by: Dropping pressure (rocks coming up quickly)/Added water
Geothermal gradient – The gradual increase in heat as you go deeper into the earth
Mantle is made of silly-putty-consistency slow-flowing rocks
Mafic (Max): Basalt – Higher melting temperature, less viscous, most common lava for Earth
Shield volcanoes – Shallow, very gentle slope
MORB – Mid-Ocean Ridge Basalt – Stuff that erupts from nearly every mid-ocean ridge volcano on Earth
Felsic (Max): Rhyolite – Retains shape really well
Magma chambers generally have conduit leading down
S Wave – Perpendicular – Transverse (up down up down)
P Wave – Back and Forth – Longitudinal (back forth back forth)
Ground Tilt – Used to determine magma stuff
Sill – Rising magma, moves with layers
Dike – Rising magma, moves across layers
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Basaltic Lava Types
- Aa – Cooler, thicker, like a pile of rocks
Pahoehoe – higher temperature, runnier, like honey, ropy texture at end
Cinder cone – Common , small, explosive central vents, like rock launched up, few hundred meters tall, like sand poured out of hand
but with big rocks called cinders, basalt, big pile of debris
Strato Volcano/Composite Cone – Classic volcano, silicate, Mt. St. Helens, get larger than cinder cones, layers of cinder/ash/lava,
layered (hence “strato”), active for long periods of time, explosions make irregular surface, lots of small eruptions
Caldera-Style SUPERVOLCANOOOO – Massive, form giant depressed valleys when their magma chamber collapses (calderas),
thought to be responsible for a lot of the lesser extinctions on Earth
Tuff – Gangsta way to spell “tough”, also compressed volcanic ash into fake rocks
Domes – Dacitic magma forms on volcano, blob
Tambora – “Year without a summer”, 1815-ish enormous eruption
Krakatau – Smaller than Tambora but still frickin’ huge, 1883
Volcanic Explosivity Index (VEI)
1
2
3
4__________________________________________________________5 > 1 km^3 (Mt. St. Helens)
6 > 10 km^3 (Pinatubu, Krakatau)
7 > 100 km^3 (Tambora, Thera, Mt. Mazama, Long Valley)
8 > 1000 km^3 (Taba, Yellowstone)
Plennian Eruptions – Large mushroom cloud
Pyroclastic Flows – Fast, hot, deadly, air
Airfall – Gets sorted as it falls. From the air. Nyur nyur nyur
Lahar – Colossal mud flows formed because of tuff and ash mixing with dirt and making it less stable
Jokulhaups – Giant floods that come from volcano erupting under a glacier
Pyroclastic particles – Volcanic debris ranging from ash (smallest) to blocks (biggest)
Volcanic Breccia – Solidified debris – angular chunks in finer grain background
Varvs – Annual layers that form in some sedimentary rocks in the same manner as tree rings
Carbon (14) Dating – Only works for relatively recent stuff because it decays so quickly, also doesn’t really work for stuff after 1940
due to atmospheric nuclear testing
Half-Life – Average time when half of nuclei disappear (for Carbon 14 about 5,730 years)
Dendrochronology –Dating using tree ring counting