theImage.com     Notes on Basic Geology
Notes created & information organization based on the book:
"The Dynamic Earth - an introduction to physical geology"
Brian Skinner & Stephen C. Porter   (further book information here)
also look at www.wiley.com for additional resource information
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Volcanoes & Magma - Page 12

Translating the Greek!

Words that indicate ... TEXTURE

pyroclast

fiery - pieces

tephra

deposit of pyroclast

bombs

> 64 mm tephra

agglomerate

Rock - bombs

lapilli

2 - 64 mm tephra

ash

< 2 mm tephra

tuff

Rock - lapilli or ash

magma

molten rock above or below

lava

magma on the earth

porphyry

coarse grains & fine grains mixed

phanerite

large grained

aphanite

very fine grains

Words that indicate ... CHEMISTY

rhyolite

fine grained

extrusive

silica rich --- olivine poor

dacite

fine grained

extrusive

intermediate

andesite

fine grained

extrusive

basalt

fine grained

extrusive

silica poor --- olivine rich

granite

coarse grained

intrusive

silica rich --- olivine poor

granodiorite

coarse grained

intrusive

intermediate

diorite

coarse grained

intrusive

gabbro

coarse grained

intrusive

peridotite

coarse grained

intrusive

silica poor --- olivine rich

Words that describe ... SHAPE

plutons

general class of underground magma cavities

dikes

diagonal or vertical intrusions cutting across strata

sills

intrusions that run parallel to strata

laccoliths

a sill with a domed roof that bends strata upward

batoliths

large bodies of underground magma

stocks

a small batholith

vent

cylindrical pipe that brings lava to the surface

pipe

a solidified vent

neck

the remains of an eroded pipe

xenolith

a sinking bit of "intruded" rock
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