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Processes of Rock and
Soil Formation
Mineral Formation

 Minerals are naturally-occurring solids.
 Minerals are formed when magma or lava cools.
 Minerals are also formed when water evaporates out
of chemical solutions.
Minerals
Naturally-occurring solids

 Minerals are substances found in nature.
 Minerals are solid.
 Minerals are inorganic.
 Minerals are made of atoms.
 Some minerals are made of only one kind of atom.
 Most are made of different types of atoms
 There are more than 3,500 different kinds of minerals
on Earth.
Mineral
Properties

 Color: Color is not the best identifying property.
 Hardness: Moh’s hardness scale: 1 to 10
 Streak: The colored line a mineral makes on a plate.
 Cleavage and fracture: How a mineral breaks.
 Luster: The amount of light reflected.
 Crystal Shape: Atoms arrange in specific patterns
depending on the mineral
 Fluorescence: Glow in black light
 Magnetism: An attractive force within some minerals
Mineral Uses

 Minerals are used for many different types of things.
Rocks

 Rocks are made of minerals.
 Sheets of rock lie beneath Earth’s soil and water.
 This part of the Earth we call the crust.
 Most of the rocks we see are pieces that have broken off
Earth’s crust.
 They are classified by their formation and composition.

Igneous
Rocks
 Igneous rocks are made deep inside Earth.
 These rocks are made from magma.
 Magma is melted rock deep inside Earth.
 When magma cools, it becomes solid rock.
 Sometimes magma flows out of holes in Earth’s crust
called volcanoes.
 When lava cools it also hardens into igneous rocks.
 Some rocks cools slowly and some cool quickly.
Types of Igneous Rocks

Granite
Obsidian
Scoria
Basalt
Pillow Basalt
Pumice
Metamorphic Rock

 Metamorphic rocks are made out of other kinds of
rock.
 Heating and squeezing change the minerals inside
the rock and they become metamorphic.
 Rocks are pushed and squeezed inside Earth.
 Sometimes the tectonic plates push against one
another forcing the rocks to be squeezed together.
Metamorphic rocks

Marble
Garnet
Slate
Rose Quartz
Gneiss
Sedimentary Rocks

 Sedimentary rocks form on Earth’s surface of just
beneath it.
 They are made of small pieces called sediments.
 Sediments can be mud, sand, stones, shells or bone.
 When sediments harden together, they become
sedimentary rock.
Types of Sedimentary Rock

Chert
Shale
Bauxite
Conglomerate
Breccia
Coquina
 Rock Cycle
 Rocks are part of a cycle, or pattern, that happens
again and again.
 The rock cycle changes old rocks into new ones.
 Water, wind and ice change rocks.
 Heat changes rocks.
 Movement can push rocks inside Earth.
Forces within the Cycle

Weathering &
Erosion

 Weathering is the wearing down of rock over time.
 Erosion is when rocks are carried by water, wind or
ice.
Deposition

 This is the process where rock and sediments are
carried and then deposited in a certain area.
Weathering

 Weathering is the process that decomposes or breaks
down exposed rock.
 One type is chemical
 Another type is mechanical
Weathering Formations

 Bridges and arches form when rocks have been
weathered and eroded.
 Chemical
 Mechanical
Weathering

Fossils

 Fossils are the hardened remains of plants and
animals that lived more than 10,000 years ago.
 Fossils are also the traces and evidence of plants and
animals that lived more than 10,000 years ago.
Fossil Types

 Preserved remains
Carbon Films
 Mineral replacement
Molds & casts
Preserved Fossils

 Fossils are plant and animal remains that have been
naturally preserved.
 Most remains disappear over time.
 Fossils that remain usually get buried and the remains are
protected.
 They are hidden from animals and are safe from water
and wind.
 Index fossils were species
that were abundant and
then became extinct
rather quickly.
Deposition

 Deposition is when sediments that are carried are
deposited.
 It is because of deposition that many fossils are
preserved.
Relative Age
relative order of past events
 This is a way of finding the
without determining their absolute age.
 Fossils are often used to correlate on stratigraphic
column with another.
 Index fossils are most useful in determining relative age.
Law of Superposition

 The Law of Superposition states that:
 In undisturbed rock layers, the oldest rocks are on
the bottom.
 Unless some force disturbs the layers after they were
deposited, each layer of rock is younger than the
layer below it.
Law of Horizontality

 Most rock-forming materials are deposited in
horizontal layers.
 Even though they might be tilted, all the layers were
originally deposited horizontally.
Intrusions and
Extrusions

 One of these is from magma (intrusions) and one of these
is from lava (extrusion).
 Both of them are younger than the layers they cut
through.
Earthquake

 Earthquakes occur when there is movement caused
by the breaks in Earth’s lithosphere.
Earthquakes

 An earthquake is what happens when two blocks of Earth
suddenly slip past each other.
 Tremendous vibrations occur with the energy traveling in
waves.
 Earthquakes have tremendous amounts of kinetic energy.
 The location directly above it on the surface of the Earth is
called the epicenter.
Folding and Faulting

Folding occurs when
rock is compressed as
it is along colliding
plate
boundaries
These normally happen as a result of an earthquake
Faulting occurs when
enormous stresses
Build up and push intact
rock layers beyond their
limit.
Volcanoes

 The Earth has its own internal heat source that
provides energy for our dynamic planet.
 A volcano is a vent in Earth’s crust through which
lava, steam and ashes are expelled.
Volcanoes and Energy

 Geothermal energy is produced within the Earth’s core




and is the force for the volcano.
Very high temperatures are continually produced inside
the Earth by the slow decay of radioactive particles.
Magma comes close to Earth’s surface by the edges of the
plates where volcanoes occur.
Geothermal energy is a renewable source produced deep
within the Earth.
Most volcanoes occur at
plate boundaries.
Hot-Spot Volcanoes

 These volcanoes are far from plate boundaries.
 They are believed to be caused by convection currents in
the mantle.