- the evolution of Earth Materials
- interaction of internal and surface processes
- Rock Types
A. Igneous
B. Sedimentary
C. Metamorphic
II. Igneous Rocks
A. Igneous Rocks = Earth’s "new" rocks
= from magma (molten rock) => crystalline
=> the result of Earth’s Internal Processes
B. Heat from Earth’s Internal Engine can melt materials in two ways
1. Heat brought up towards the surface
Convection => divergent boundaries
- melting of upper mantle rocks
2. Take the rocks closer to the Earth’s Heat Engine
Subduction => convergent boundaries
- melting of rocks on ocean floor
C. Crystallization of Magma
=> 2 major types of igneous rocks
(1) Volcanic(extrusive)
(2) Plutonic(intrusive)
=> difference = texture
=>Texture of Igneous Rocks => depends on rate of cooling
=> texture = crystal size...........
1. slow cooling -> deep within crust
crystals coarse (visible) = phaneritic texture
rocks = intrusive or plutonic
2. fast cooling -> at surface (in air or water)
fine crystals (invisible) = aphanitic texture
rocks = extrusive or volcanic
D. Composition of Igneous Rocks
- three categories -> magma and rocks
1. Mafic magma and rocks - mafic (Fe & Mg)
2. Felsic magma and rocks - rich in Si
3. Intermediate
E. Important Properties
1. Texture
2. Composition
- clues about
- origins
- processes
older rock =>weathering =>sediment =>transport=>deposition =>lithification
Sedimentary Rocks
Contain: information about surface conditions while sediments were being created, transported, and deposited....
Information including => past environments, climates, and life
- also important => natural resources
- hydrocarbons
- Oil, gas, and coal
B. Weathering => the physical breakdown and chemical alteration of pre-existing rocks
two types => 1) mechanical
& 2) chemical
- physical
- chemical reactions
- particles - solutions
C. Sediment => particles and solutions created by weathering and deposited elsewhere.....
D. Transport = what moves sediment?
4 agents = 1. Gravity, 2. Wind, 3. Water, and 4. Ice
E. Deposition => occurs when transport ends
1. Depositional Environments - a. marine, b. continental
F. Lithification => converting loose sediment into solid rock
=> burial leads to
a) compaction b) cementation
- Important characteristics of Sedimentary Rocks
Texture
Components
Clues about origin and history of rock including:
- environments, climate, and life
Earth Materials
Metamorphic Rocks
• Metamorphic Rocks = Pre-existing rocks are transformed
• by high P and/or T
• - the result of internal processes
• Pressure and Heat
• changes composition and/or texture of pre-existing rocks
=> metamorphism = a change occurring in the solid state
Types of Metamorphism and Common Metamorphic Rocks
Two Types => 1) Regional and 2) Contact
Regional Metamorphism
-> takes place at great depth over an extensive area....
=>> associated with mountain building..........
Foliated - regional metamorphic rocks
- slate (parent = shale)
foliation = slatey cleavage
- schist (parent = slate or igneous rock)
foliation = schistose / schistosity
- gneiss (parent = schist or igneous rock
foliation = gneissic banding
Clues about internal processes from metamorphic Rocks
=> Mineral assemblagesand texture can act as thermometers and barometers
• texture and mineralogy of met. rx. reflect degree of metamorphism
= metamorphic grade