Post on 13-Jan-2016
TThhee RRoocckk CCyycclle e TThhee RRoocckk CCyycclle e
What is tWhat is thhee
RRoocckk CCyycclle ?e ?
The RRoocck k CCyycclle e explains how RocksRocks and Natural ProcessesNatural Processes
are related
weathering
melting
pres
sure
, hea
t
Sedimentary Metamorphic
Igneous
is a sequence of events involving the
formation, alteration, destruction, and reformation of rocks as a result of natural processes ...
Glossary of Geology, Bates & Jackson, AGI
RRoocckk CCyycclleeA more traditional definition is:
We will use the graphic seen in the background to help
represent the RRoocck k CCyycclle.e.
There are many ways to show the various relationships between the rocks and
the related natural processes.
let’s review some basic information …
Before we look at the
RRoocck k CCyyccllee
in detail,
The RRoocck k CCyyccllee involves the recognition of three main classes of rocks.
The three rock types are …
CEMETERYCEMETERY METABOLICMETABOLIC
INGENIOUSINGENIOUS
SedimentaryRocks
MetamorphicRocks
IgneousRocks Right?Right?
The eminent 18th century lawyer, doctor, gentleman farmer and founder of modern geoscience,
James HuttonJames Hutton, developed the concept of the RRoocck k CCyyccllee to show how rocks and natural, physical processes are interrelated.
The understanding of the world in the 18th century was different from today …
Hutton knew about solar energy and gravity at the surface. He did not know about radioactive heating from inside the earth.
As a result, the RRoocck k CCyyccllee
will be self-sustaining for thousands of millions of years.
Solar energy, gravity and radioactive heating are the major forces driving the RRoocck k CCyyccllee.
How does an antique concept like the RRoocck k CCyyccllee hold up in light of contemporary data and scientific thinking?
Of special interest is Plate Tectonics.
The mantle, crust and surface of the earthcan be thought of as a giant recycling machine;rocks are neither created nor destroyed, but redistributed and transformed from one rock type to another.
IM
S
If you were to ask a geologist what the earth is …
What do you think theresponse would be?
Diagram of the Interior of the EarthCrust
0 to 40 km 0°C
Upper Mantle40 to 670 km
1,000°C
Lower Mantle670 to 2,890 km
2,000°C
Outer Core2,890 to 5,150 km
3,700°C
Inner Core5,150 to 6,370 km
4,300°C
lets move to some of the smallest components of Geology …
Now that we better understand the largest components of Geology …
.
Minerals make up rocks.
Natural compounds and elements combine to form minerals.
Elements combine to form the natural compounds.
Rocks make up the Earth.
There is a hierarchy to the elements of Geology
Atoms make up elements.
Elements can be arranged, based on their identifiable properties, into the Periodic Table
Atomic Theory proposes that all matter is composed of the atoms of about 100 different chemical elements. It further proposes that chemical compounds are formed by the combination of the atoms of different chemical elements.
Only eighteight elements make up over 98%
of the earth’s crust!
Mg
Na
K
OSiAl
FeCa
.
Minerals make up rocks.
Natural compounds and elements combine to form minerals.
Elements combine to form the natural compounds.
Rocks make up the Earth.
There is a hierarchy to the elements of Geology
Atoms make up elements.
What are Minerals? How can we tell what they are?
The identifiable The identifiable
characteristics ofcharacteristics of MineralsMinerals areare
naturally occurring inorganic elements or naturally occurring inorganic elements or compoundscompounds
having an orderly internal having an orderly internal structurestructure
and a characteristic chemical and a characteristic chemical compositioncomposition,
crystal form andcrystal form and
physical properties of a physical properties of a solidsolid
MineralsMinerals combine to form combine to form
RocksRocks
Some RRoocckkss are made up of just one
mineral - like the sedimentary rock salt (made up of the mineral halite).
Others RRoocckkss are made up of many minerals - like the igneous rock
granite and the metamorphic rock
gneiss, found near Marquette.
Now that some of the basicshave been covered, letsconsider some of the
details about the
RRoocckk CCyyccllee
The RRoocck k CCyyccllee
weathering
Sedimentary Metamorphic
Igneous
Rocks are weathered,eroded,transported,deposited,and lithified to formsedimentary rocks
The igneous rock granite canbe physically weathered to produce clay and sand.
Becoming a SEDIMENTARY ROCK …
Sand can become sandstone.
Clay can become shale
These sediments can be transported deposited and lithified to form sedimentary rocks.
The metamorphic rock gneiss can be physically weathered to produce clay and sand.
Becoming a SEDIMENTARY ROCK …
Sand can become sandstone.
Clay can become shale
These sediments can be transported deposited and lithified to form sedimentary rocks.
Sedimentary rocks can be physically weathered to produce sediments that can become other sedimentary rocks.
Becoming a SEDIMENTARY ROCK …
As the ice advancesit can scour the bedrockand move a lot of material.
When the ice retreats,sediments are deposited and new set of landforms exist.
The RRoocck k CCyyccllee
melting
Sedimentary Metamorphic
Igneous
Igneous Rocksform from molten rock or magma in the subsurface or from lava extruded at the surface
Becoming an IGNEOUS ROCK …
When magma cools to a solid it becomes an igneous rock.
Molten rock is called magma.
Any existing rock – igneous, metamorphic or sedimentary - can be subjected to enough heat and or pressure causing it to melt.
The kind of igneous rock formed depends on what was melted and how it cooled.
Igneous rocks are classified based on their mineral composition and texture.
basaltgranite
granodiorite
rhyolite
pegmatite
Igneous rocks:
pres
sure
, hea
t
Sedimentary Metamorphic
Igneous
The RRoocck k CCyyccllee
Pressure, Pressure, heatheatand fluidsand fluids cause preexistingrocks or sediments to becomemetamorphic metamorphic rocksrocks
Becoming a METAMORPHIC ROCK …
When the prefix meta is applied to a rock name that means that the original rock has been metamorphosed.
If the igneous rock basalt is exposed to sufficient heat and or pressure it can be transformed into the metamorphic rock call metabasalt
Becoming a METAMORPHIC ROCK …
If the sedimentary rock sandstone is metamorphosed it can become the metamorphic rock quartzite.
If the sedimentary rock limestone or dolomite is metamorphosed it can become the metamorphic rock marble.
If the sedimentary rock shale is metamorphosed it can become the metamorphic rock slate.
Becoming a METAMORPHIC ROCK …
If the metamorphic rock phyllite is metamorphosed it can become the metamorphic rock schist.
If the metamorphic rock slate is metamorphosed it can become the metamorphic rock phyllite
If the metamorphic rock schist is metamorphosed it can become the metamorphic rock gneiss.
weathering
melting
pres
sure
, hea
t
Sedimentary Metamorphic
Igneous
The RRoocck k CCyyccllee
The RRoocck k CCyyccllee
does not go in just one direction. Any given rock can go through any part of the cycle any number of times.
weathering
melting
pres
sure
, hea
t
Sedimentary Metamorphic
Igneous
The RRoocck k CCyyccllee
I hope you better understand the RRoocck k CCyyccllee
and what it means.