THE ROCK CYCLE
& ROCKS
Subtitle
3. Three rocks that do not have minerals or are composed of nonmineral
matter.
• Coal
• Pumuce
• Obsidian
THE ROCK CYCLE
Why do scientists study rocks?
• Rocks contain clues about the environment in which they were
formed.
• Volcanic rocks tell a story of volcanic activity
1. A rock is any solid mass of minerals or mineral-like
matter that occurs naturally as part of our planet.
2. The three major types of rocks are igneous rocks,
sedimentary rocks and metamorphic rocks.
THE ROCK CYCLE
1. Interactions among Earth’s (spheres) water, air and land
can cause rocks to change from one type to another. The
continuous processes that causes rocks to change make
up the rock cycle.
THE ROCK CYCLE
2. When magma cools and hardens beneath the surface or
as the result of a volcanic eruption, igneous rock forms.
THE ROCK CYCLE
3. Weathering is a process in which rocks are physically
and chemically broken down by water, air, and living
things to produce sediment.
THE ROCK CYCLE
4. Sediment is made up of weathered pieces of earth materials.
Sediment is moved and deposited by water, gravity, glaciers, or
wind.
THE ROCK CYCLE
5. Eventually, sediment is compacted and cemented to form
sedimentary rock.
THE ROCK CYCLE
6. Under extreme pressure and temperature conditions,
sedimentary rock will change into metamorphic rock.
a) If the sedimentary rock melts, it changes to igneous rock
THE ROCK CYCLE
7. Processes driven by heat from Earth’s interior are responsible
for forming both igneous and metamorphic rocks.
THE ROCK CYCLE
8. Weathering and the movement of weathered
materials are external processes powered by
energy from the sun and by gravity.
THE ROCK CYCLE
9. Processes on and near Earth’s surface produces
sediementay rocks.
THE ROCK CYCLE
9. Processes on and near Earth’s surface produces
sediementay rocks.
IGNEOUS ROCK
HOW ARE INTRUSIVE ROCK AND EXTRUSIVE IGNEOUS
ROCKS ALIKE OR DIFFERENT?
1. Different kinds of igneous rocks from when magma and
lava cool and harden.
HOW ARE INTRUSIVE ROCK AND EXTRUSIVE IGNEOUS
ROCKS ALIKE OR DIFFERENT?
2. Intrusive igneous rock form when magma hardens
beneath Earth's surface
a) Silicon, oxygen, plus aluminum, iron, calcium, sodium,
potassium, and magnesium and some gases (water vapor)
HOW ARE INTRUSIVE ROCK AND EXTRUSIVE IGNEOUS
ROCKS ALIKE OR DIFFERENT?
b) Magma is less dense, it slowly works it way up toward
the surface
i. As it rises, it cools-allowing elements to cool and combine to
form minerals
ii. Minerals growing size, forming a solid mass of interlocking
crystals
iii. granite
HOW ARE INTRUSIVE ROCK AND EXTRUSIVE IGNEOUS
ROCKS ALIKE OR DIFFERENT?
3. Extrusive Igneous rock forms when lava hardens.
a) Gases have escaped
b) Rhyolite
HOW DOES THE RATE OF COOLING AFFECT AN IGNEOUS
ROCK’S TEXTURE
1. Texture and composition are two characteristics used to
classify igneous rocks.
a) Texture describes the appearance based on size, shape and
arrangement of its interlocking crystals.
b) Composition is based on the proportions of light and dark
minerals in the rock.
HOW DOES THE RATE OF COOLING AFFECT AN IGNEOUS
ROCK’S TEXTURE?
2. Coarse-grained texture
a) Slow cooling of magma or lave results in the formation of large
crystals
HOW DOES THE RATE OF COOLING AFFECT AN IGNEOUS
ROCK’S TEXTURE?
3. Fine-grained texture
a) Rapid cooling of magma or lava results in rocks with small,
interconnected mineral grains
HOW DOES THE RATE OF COOLING AFFECT AN IGNEOUS
ROCK’S TEXTURE?
4. Granitic compositions
a) Silicate minerals, Quartz and feldspar plus 10% dark silicate
minerals (biotite mica & amphibole)
b) 70% silica
c) Rhyolite, extrusive granitic rock
d) Intrusive granitic rock make up most of the continental crust.
HOW DOES THE RATE OF COOLING AFFECT AN IGNEOUS
ROCK’S TEXTURE?
5. Basaltic compositions
a) Dark silicate minerals and plagioclase feldspar
b) Rich in magnesium and iron
c) Typically darker an denser than granitic rocks
d) Basalt
e) Gabbro is an intrusive igneous rock with basaltic composition
f) Makes up ocean floor
SEDIMENTARY ROCKS
DESCRIBE THE MAJOR PROCESSES INVOLVED IN THE
FORMATION OF SEDIMENTARY ROCKS.
1. Several major processes contribute to the
formation of sedimentary rocks.
2. Weathering, erosion and deposition
a) Weathering, any process that breaks rocks into
sediments (rain, water freeing, growing plants etc…)
b) Erosion involves weathering and the removal of rock.
When an agent of erosion-water, wind, ice or gravity—
loses energy, it drops the sediments in the process
called deposition.
DESCRIBE THE MAJOR PROCESSES INVOLVED IN THE
FORMATION OF SEDIMENTARY ROCKS.
3. Compaction and cementation
a) Change sediments into sedimentary rock
b) Compaction is the process that squeezes, or compacts, sediments.
i. Compaction is caused by the weight of sediments.
ii. Water in the sediments is squeezed out
c) Cementation takes place when dissolved minerals are deposited in the
tiny spaces among the sediments
WHAT ARE CLASTIC SEDIMENTARY ROCKS?
WHAT ARE CLASTIC SEDIMENTARY ROCKS?
1. Sedimentary rocks can be classified into two main
groups according to the way they form.
2. Clastic sedimentary rocks
a) Many different minerals
b) Most common are clay and quatz
c) Can be grouped according to the size of the sediments in the
rocks
d) Rounded, Large particles, are called conglomerate
e) Angular particles are called breccia
f) Sand- size grains are called sandstone
WHAT ARE CHEMICAL SEDIMENTARY ROCKS?
3. Chemical sedimentary rocks form when dissolved substances precipitate
or separate from water solution
a) Water evaporates or boils off leaving a solid product
b) Limestone, rock salt, chert, flint, and rock gypsum
WHAT FEATURES ARE UNIQUE TO SOME SEDIMENTARY
ROCKS?
1. The many unique features of sedimentary rocks
are clues to how, when and where the rocks
formed.
a) Each layer, is a record of time (history)
b) Fossils are found in sedimentary rocks
c) Can answer questions like:
i. What kind of climate? Hot or cold
ii. Did it form in an ocean or on land?
iii. When did the rock form? Hundreds, thousands, millions or
billions of years ago?
METAMORPHIC ROCK
GEOSPHERE
1. The geosphere is not uniform, it is divided into three main parts based
on differences in composition– the core, the mantle, and the crust.
WHERE DOES MOST METAMORPHISM TAKE PLACE?
1. Most metamorphic
changes occur at
elevated temperatures
and pressures. These
conditions are found a
few kilometers below
Earth’s surface and
extend into the upper
mantle.
HOW IS CONTACT METAMORPHISM DIFFERENT FROM
REGIONAL METAMORPHISM?
1. Contact metamorphism
a) During contact
metamorphism, hot-magma
moves (forces) into rock
b) Produces low-grade
metamorphism
c) Minor changes to the rock
d) Marble forms when magma
intrudes a limestone rock
HOW IS CONTACT METAMORPHISM DIFFERENT FROM
REGIONAL METAMORPHISM?
2. Regional
metamorphism
a) Mountain building
b) Extreme heat and
pressure
c) Regional
metamorphism result
in large-scale
deformation and highgrade metamorphism
WHAT ARE THREE AGENTS OF METAMORPHISM, AND
WHAT KINDS OF CHANGES DOES EACH CAUSE?
WHAT ARE FOLIATED METAMORPHIC ROCKS AND HOW
DO THEY FORM?
HOW ARE METAMORPHIC ROCKS CLASSIFIED?