The Rock Cycle its Story

Formation of Rocks in More Detail

Do Now:

• Every day the man-Mr. Doughman, bakes the cookies. He makes the dough, puts it in the oven, and bakes them. Then he lets them cool and harden. Another man –Mr. Crumbles, takes the cookies and crumbles them, building up layer and layer of cookies. Then Mr. Squeezy comes along and takes all the cookies and squeezes them together over and over. The cookies get warm again in his hands as he does this. The sun sets and rises, and Mr. Doughman makes the cookies again, over and over…

Hey, that’s a lot of cookies…

• Compare the gentlemen in the story to the Rock types we learned about:– Mr. Doughman– Mr. Crumbles– Mr. Squeezy

– Something that occurs over and over again is________________?

See p6 ESRT

• To Read the Rock Cycle, follow the arrows around

Start with Magma, these are types of Igneous Intrusions which will become

Igneous Rock

Sometimes pieces of the surrounding rock remain unmelted and become part of the igneous rock (xenolith)

Igneous Intrusions-cut through the parent rock

Making Sediments and Sedimentary Rock…

• Uplift• Weathering • Erosion• Deposition• Burial• Compaction• And Cementation (natural glue- silica, calcite

or iron oxides)

Sediment Sorting in Land Derived Sedimentary Rocks

Sorting of sediments produces separation of the particle sizes(p6)

• Pebbles/gravels are dropped first (form conglomerate)

• Sands (form sandstone)• Silts, clays are dropped last (form

shale)

Chemical Origin in Chemically formed Sedimentary Rock

• Water contains dissolved minerals, which can fall out of solution (precipitate) due to evaporation or chemical action

• Limestone can be formed from tiny grains of calcite deposited from sea or lake waters

• Other examples are rock salt (halite) and rock gypsum

Organic Origin

• Calcite is dissolved out of rocks on land, carried to an ocean or lake, and taken out of the water by shell-producing organisms (eg. Clams, oysters, sea snails)

• When these organisms die, their shells pile up and are broken down into fragments, and can form organic limestone

Metamorphism…

• Metamorphic rocks are not formed from magma or sediment

• Metamorphic rocks “morph” (change) from existing rock, due to heat, pressure and chemicals

• Pressure squeezes grains closer together (more dense, less porous)

• Heat and chemicals may rearrange the particles (new minerals may be formed)

Types of Metamorphism

Regional Metamorphism: large areas of rock are under intense heat/pressure, which occurs during mountain-building

• Heat comes from friction of rocks, and pressure from overlying weight and the squeezing of moving rocks

Contact Metamorphism: when hot magma forces itself into overlying rock (intrusions) and bakes the rock

Contact Metamorphism

Results in Folations if more then one mineral makes up rock

• Occurs when the pressure on the rocks squeezes minerals into parallel layers

• The rocks tend to split easily along these layers

What is the Rock Cycle?• Is the repeated series of events by which rock

gradually and continually changes from one type to another

• Theses events are geological events-meaning they happen in the Earth’s crust or on it

• Another word to describe this is geologic process

• Can you name some of these processes?

Reading the Rock Cycle Chart

• See page 6-7 in the ESRT

• First Classify your Rock Samples-work together with your partner

• Place them on the Rock Cycle diagram enlarged copy-work together to complete Part II of Lab

Complete Understanding the Rock Cycle-for homework

1. When granite changes into schist, what geologic processes does it have to undergo? 2. Change gneiss into conglomerate, which geologic processes are involved? 3. Which type of rock can change into the same kind of rock without going through the entire rock cycle?

Sum Up:

• What are 3 great “truths” about the Rock

Cycle? Think about everything we talked about today and see if you can list them below:

Sum Up: (well maybe 5 truths…)

1. The Rock Cycle is a model of the natural changes that occur in rocks and rock material

2. Shows all Rocks are made from other rocks or rock remains

3. Shows Rocks are classified upon basis of formation4. Shows that there are a variety of ways that rocks

can change at the surface or within the Earth5. It keeps on going and going….and has been since

the Earth’s Spheres formed

Follow up Assignment: • Complete a RAFT to help you understand Rocks and the Rock Cycle

better. The directions are as follows: • Role-You are a Geologist• Audience-Students in a High School Earth Science Class• Format-Can choose any way to write this-poem, story, email, riddle,

song, etc…• Topic: Earth’s Dynamic(Ever Changing) Crust and the Rock Cycle • Be prepared to share your RAFT with the class on Tomorrow! (read

aloud)

Food for thought…

• Do we have any influence on the Rock Cycle? If so, what?

• What force is driving the Rock Cycle?