Rocks

What are they?

The Rock Cycle4/15/15

• Key Question: What are rocks and where do rocks come from?

• Initial Thoughts:

Evidence #1What is a rock?

• A rock is a mixture of minerals, rock fragments, volcanic glass, organic matter, or other natural materials.

• Most rock used for building stone contains one or more common minerals, called rock-forming minerals, such as quartz, feldspar, mica, or calcite

• When you look closely, the sparkles you see are individual crystals of minerals.

Rock Types

• There are three types of rocks

Igneous

Sedimentary

Metamorphic

What is the rock cycle?

• To show how rocks slowly change through time, scientists have created a model called the rock cycle.

• It illustrates the processes that create and change rocks.

Rock Cycle Continued

• The rock cycle shows the three types of rock— igneous, metamorphic, and sedimentary—and the processes that form them.

The Rock Cycle explains how Rocks and Natural Processes

are related

weathering

melting

pres

sure

, hea

t

Sedimentary Metamorphic

Igneous

What is the law of conservation of matter?

• Law of conservation of matter states that matter cannot be created or destroyed.

• The changes that take place in the rock cycle never destroy or create matter.

• The elements are just redistributed in other forms.

Evidence #2: Dice Game

Paste your log into your journal

You will roll a minimum of10 times, and follow the directions on the dice at each station.

Record each step in your log.

Stations#1 Compaction and

Cementation

#2 High Temperature and Pressure

#3 Sediments

#4 Igneous Rock

#5 To The Surface

#6 Metamorphic Rock

#7 Sedimentary Rock

#8 Melting

#9 Cooling and Hardening

#10 Magma

#11 Weathering and Erosion

Evidence #3:What are Rocks?

• A rock is a naturally occurring solid mixture of one or more minerals, or organic matter

• Rocks are classified by how they are formed, their composition, and texture

• Rocks change over time through the rock cycle

ROCKS

Rock Types

Rock Types

Rock Types

Rock Types

• Believe it or not , rocks can be classified into groups

-Just like living organisms

• The three main groups are:

IGNEOUS SEDIMENTARYMETAMORPHIC

• What are the clues to help classify rocks?

                                             

The Rock Cycle

melting

The Rock Cycle

Igneous Rocks

Igneous means “born of fire”

Igneous Rocks

• Igneous rock begins as magma.• Magma can form:

• When rock is heated• When pressure is released• When rock changes composition

• Magma freezes between 700 °C and 1,250 °C

• Magma is a mixture of

many mineralshttp://www.fi.edu/fellows/payton/rocks/create/igneous.htm

VOLCANOES!!!

Fig. 2.9

MAGMA

LAVA!!!

Igneous Rocks - examples

Felsic

Mafic

Coarse-Grained

Fine-Grained

Granite

Gabbro Basalt

Rhyolite

Igneous Rocks

Intrusive Igneous Rocks: magma pushes into surrounding rock below the Earth’s surface

Extrusive Rocks: forms when magma erupts onto the Earth’s surface (lava), cools quickly with very small or no crystals formedhttp://www.windows.ucar.edu/tour/link=/earth/geology/ig_intrusive.html&e

du=high&fr=t

Igneous Rocks

Obsidian

What is Obsidian?

Obsidian is a dark-colored volcanic glass that forms from the very rapid cooling of molten rock material. It cools so rapidly that crystals do not form.

Obsidian is a dark-colored volcanic glass that forms from the very rapid cooling of molten rock material. It cools so rapidly that crystals do not form.

Is this rock Felsic or Mafic?

Is it fine-grained or coarse-grained?

Is this rock Intrusive or Extrusive?

Mafic, fine grained, extrusive

                                             

The Rock Cycle

melting

The Rock Cycle

But then theEARTH’S elementsWon’t leave

The poor rock alone!

•Ice•wind •Water ice

water

wind

They break up the stone

Sedimentary Rocks

http://www.fi.edu/fellows/payton/rocks/create/sediment.htm

Sedimenary rock is formed by erosion

Sediments are moved from one place to another

Sediments are deposited in layers, with the older ones on the bottom

The layers become compacted and cemented together

Sedimentary Rock

Sedimentary Rocks are formed at or near the Earth’s surface

No heat and pressure involved

Strata – layers of rock Stratification – the process in

which sedimentary rocks are arranged in layers

Sedimentary Rock

Chemical sedimentary – minerals crystallize out of solution to become rockLimestone is a sedimentary

rock composed primarily of calcium carbonate (CaCO3) in the form of the mineral calcite. It most commonly forms in clear, warm, shallow marine waters.

It is usually an organic sedimentary rock that forms from the accumulation of shell, coral, algal and fecal debris.

Sedimentary Rock

Organic sedimentary – remains of plants and animals

Coal is an organic sedimentary rock that forms from the accumulation and preservation of plant materials, usually in a swamp environment. 

Coal is a combustible rock and along with oil and natural gas it is one of the three most important fossil fuels. 

Sedimentary Rock

Clastic – made of fragments of rock cemented together with calcite or quartzBreccia is a term most

often used for clastic sedimentary rocks that are composed of large angular fragments (over two millimeters in diameter).

The spaces between the large angular fragments can be filled with a matrix of smaller particles or a mineral cement that binds the rock together.

                                             

The Rock Cycle

melting

The Rock Cycle

Metamorphic Rock

http://www.fi.edu/fellows/payton/rocks/create/metamorph.htm

Meaning to change shape Changes with temperature and pressure, but remains solid Usually takes place deep in the Earth

Metamorphic Rocks

• Contact Metamorphism – heated by nearby magma

• Increased temperature changes the composition of the rock, minerals are changed into new minerals

Hornfels is a fine-grained non-foliated metamorphic rock produced by contact metamorphism http://www.windows.ucar.edu/tour/link=/earth/geology/meta_contact.html&ed

u=h igh&fr=t

Metamorphic Rocks

Regional Metamorphism – pressure builds up in rocks that is deep within the Earth

Large pieces of the Earth’s crust collide and the rock is deformed and chemically changed by heat and pressure

http://www.windows.ucar.edu/tour/link=/earth/geology/meta_regional.html&edu=high&fr=t

Metamorphic Rock

• Foliated - contain aligned grains of flat minerals

Gneiss is foliated metamorphic rock that has a banded appearance and is made up of granular mineral grains.

It typically contains abundant quartz or feldspar minerals.

Metamorphic Rock

• Non-Foliated – mineral grains are not arranged in plains or bands

Marble is a non-foliated metamorphic rock that is produced from the metamorphism of limestone.

It is composed primarily of calcium carbonate.

Metamorphic Rock

• Determine if the following rock samples are foliated or non-foliated:

Amphibolite Quartzite Phyllite Foliated

                                             

The Rock Cycle

melting

The Rock Cycle

Analysis Questions

Reminder: Answer in complete sentences.

1. What are rocks, and how are they created?

2. What are the 3 natural processes involved in the rock cycle?

3. How many times did you change into a different kind of rock? Describe 1 of the changes, naming the proccess(es) that caused the change.

Summary

What did you think about what rocks are and where they come from before this lesson?

What did you learn about what rocks are and where they come from from this lesson? (Minimum of 3 sentences!!!)

What are some further thoughts or questions you have about what rocks are and where they come from?

Reflection

• Write a poem, narrative, or comic about a rock going though the rock cycle.

Big Idea

• Rocks are created and changed through a process called the rock cycle.