Download Rocks and the Rock Cycle

Rocks and the Rock Cycle

The Three Rock Types Include:
1) Igneous Rocks (i.e. Fire Rocks)
2) Sedimentary Rocks (i.e. Layered Rocks)
3) Metamorphic Rocks (i.e. Changed Rocks)

All three rock types are interrelated through the rock
cycle. The three rock types are classified by their
nature of origin (i.e. formation).
Reference:
Tarbuck and Lutgens
Pages 15 - 17
Igneous Rocks
 Rocks that have solidified from a molten state.
 If the molten is located below Earth’s surface,
then it is called magma. Magma is higher in
gases than lava.
 If the molten is located on Earth’s surface, then
it is called lava. Lava is lower in gases than
magma.
 There are two classifications of igneous rock,
which include:
1) Plutonic (intrusive) – forms from magma.
2) Volcanic (extrusive) – forms from lava.
•
•
•
•
•
Igneous Rocks
Examples include:
Granite (Intrusive) and Rhyolite (Extrusive)
Diorite (Intrusive) and Andesite (Extrusive)
Gabbro (Intrusive) and Basalt (Extrusive)
Peridotite (Intrusive) and Komatiite (Extrusive)
• Note that both rocks in each pair exampled above
has the same composition; however, one formed
from a lava and one formed from a magma.
Sedimentary Rocks
 Rocks formed when the weathered products (i.e.
sediment) of pre-existing rocks have been
transported, deposited, compacted, and cemented
into solid rock. These rocks usually show
layering/strata/beds.
 Usually formed in water environments. For example,
sediment being deposited by streams and rivers.
 Most of Earth’s crust (95%) is igneous rocks; however,
the surface of the crust is largely covered by sedimentary
rocks.
 The Three classifications of Sedimentary Rocks include:
Clastic (i.e. Detrital)
Chemical
Organic
Sedimentary Rocks
• Examples include:
• Shale, Siltstone, Sandstone, Breccia,
Conglomerate, Limestone, Dolomite, Chalk,
Coquina, Coal.
• Note that clastic (i.e. detrital) sedimentary
rocks are classified by grain size.
Metamorphic Rocks
 Rocks formed below Earth’s surface when preexisting rocks (i.e. igneous, sedimentary, and even
metamorphic) are altered by heat, pressure, and
chemically active fluids (e.g. water).
 Metamorphism changes rocks in size, shape, texture,
and mineral composition.
 Metamorphism varies in degree from:
1) High Grade. E.g. Granite changes to Gneiss
2) Low Grade. E.g. Shale changes to Slate
NOTE: MELTING IS NOT INVOLVED IN THE PROCESS
OF METAMORPHISM.
Metamorphic Rocks
• Examples of metamorphic rocks include:
Quartzite, Marble, Slate, Slate, Phyllite,
Schist, and Gneiss.
• Note that there are two types of
metamorphism, which include: Contact and
Regional.
Rock Cycle
Cooling and
Crystallization
(i.e.
solidification)
Melting
Metamorphic
Igneous
(Volcanic)
(Plutonic)
Magma/
Lava
Melting
Heat, Pressure, and Hot
Chemical Fluids
Heat,
Pressure,
and Hot
Chemical
Fluids
Sedimentary
(Clastic)
(Chemical)
(Organic)
Weathering
And
Erosion
Weathering
And
Erosion
Weathering
And
Erosion
Compaction
And
Cementing
Sediment
Examples include:
sand, silt, and clay
(mud)
Sample Problem
In the diagram below, rock types/materials are indicated by numbers and
processes are indicated by letters. Indicate the rock types/materials and
processes for the rock cycle diagram by completing the table below.
A
Answer:
1. Magma
E
2.
5.
Weathering
& Erosion
B
3.
D
C
4.
Rock Type / Materials
Processes
1.
Magma
A
Cool & Crystallize
2.
Igneous
B
Weathering and Erosion
3.
Sediments
C
Compacting & Cementing
4.
Sedimentary
D
Heat & Pressure
5.
Metamorphic
E
Melting