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Rocks and the Rock Cycle
Chapter 6
The Rock Cycle
What types of rocks were the first type on
the Earth?
IGNEOUS
Bowen’s Reaction Series
Canadian Geologist,
Norman L. Bowen,
recognized that certain
minerals tend to
crystallize first. As they
crystallize, they remove
specific elements,
changing the
composition of magma
as it cools.
Partial Melting vs. Fractional
Crystallization
Classification of Igneous Rocks

Intrusive Igneous
Rocks
 Slow cooling below
surface
 Visible crystals

Extrusive Igneous Rocks
 Fast cooling at
surface
 No crystals or very
very small crystals
Textures of Igneous Rocks
Fine-grained (Rhyolite)
Coarse-grained (Granite)
Vesicular (pumice)
Porphyritic (Rhyolite)
Glassy (obsidian)
Composition of Igneous Rocks
MAFIC
FELSIC
Types of Lava
Mafic
Color
Dark
Composition
Magnesium/ir
on
Origin
Ocean crust
Temp
Hot
Viscosity
Thin
Eruption Type Quiet
Example
Hawaii
Felsic
Light
Silica,
Aluminum
Cont. crust
Cool
Thick
Violent
Mt. St. Helens
Intrusive Igneous Rock Features


Batholith – large
mass (100 square
km) of igneous
rock
Stock – smaller
version of a
batholith
Oregon Batholith after surrounding
rock has been eroded away

Laccolith – magma
pushes overlying
upward into an
arch
Bear Butte, Black Hills, South Dakota

Sill – magma flows
between layers of
rock - horizontal

A five-mile-long volcanic
wall, a dike, radiating from
Shiprock in distance
Dike – igneous
formation that cuts
across rock layers vertical
Formation of Sedimentary Rocks
Compaction
Cementation
Chemical Sedimentary Rocks
Halite (Rock Salt)
Evaporites precipitating from the hyper saline brine
water in one of the playa lake, Thar desert
Gypsum Rock
Organic Sedimentary Rock
Chalk
Coal
Limestone with Fossils
Clastic Sedimentary Rock
Conglomerate (Round)
Sandstone (Sand-sized grains)
Breccia (Angular)
Shale (Clay-sized particles)
Sedimentary Rock Features
Cross-beds
Stratification in the Grand Canyon
Mud Ripples
Formation of Metamorphic Rock
Contact Metamorphism
Formation of Metamorphic Rock
Regional Metamorphism
Types of Metamorphic Rock
FOLIATED ROCK
Slate: metamorphic shale
Gneiss: metamorphic granite
Types of Metamorphic Rock
NONFOLIATED ROCK
Quartzite: metamorphic quartz
sandstone
Marble: metamorphic limestone