The Rock Cycle Why is the Rock Cycle

The Rock Cycle

Why is the Rock Cycle Important? It is part of Earth’s continuously changing Surface

The Earth’s Changing Surface § There are many different types of changes on the Earth’s surface § Some are quick § Earthquakes § volcanoes § landslides § Some are slow § Weathering § Erosion § The Earth’s surface is always changing

What is Weathering?

Weathering is: § The process of breaking down rocks into smaller and smaller pieces § Rain, wind, moving water, & the sun are causes of weathering

What is Erosion?

Erosion is: § The process that involves the movement of Earth’s materials from one place to another § Wind, water, & ice are causes of erosion

The Rock Cycle § Weathering and Erosion play a huge role in the rock cycle § It is a process of change on the Earth’s surface § Rocks are constantly being formed and destroyed

What are rocks?

Rocks are: § Solid materials that are made up of more than one mineral § They are: § § Mountains Canyons Riverbeds Pebbles on the street

How are Rocks formed?

Through the Rock Cycle § It takes thousands to millions of years for rocks to change § Melting, heat & pressure, weathering & erosion, & cementing and compacting can all cause one type of rock to turn into another type of rock!

The Steps of the Rock Cycle § The Earth pushes rock up to the surface forming Igneous Rocks. § They are formed when magma or lava cools and hardens.

Igneous Rocks § At the surface, the rocks go through changes caused by erosion, weathering, and compacting, or cementing

What is Compacting and Cementing?

Compacting and Cementing is: § When accumulated (collected) sediment (pieces of rock) are pressed together for a long period of time § It usually occurs when sediment flows into a body of water and the pressure of the water “squeeezes” the sediment, compacting it § They are pressed together for so long that they form which kind of rock?

Sedimentary!

§ Eventually the squeezing forces press the sedimentary rock back down into the Earth § Once they get back into the Earth heat and pressure causes them to turn into….

Metamorphic Rock!

§ The intense pressure and heat underground presses the metamorphic rock together, and, over time, can melt it into magma § Some of that magma reaches the Earth’s surface and cools off where it becomes a solid, what kind of rock again?

That’s right! Igneous rock!

All About Igneous Rocks!

What are igneous rocks? § Igneous rocks form when hot, melted rock cools and hardens § Igneous means made from fire or heat § They are called “fire” rocks

How are Igneous Rocks Formed? § Igneous rocks may form on the Earth’s surface (extrusive) or they may form within the Earth’s surface (intrusive) § When rock is a liquid inside the Earth it’s called magma

How are igneous rocks formed continued… § When magma flows out of the Earth’s surface, like during a volcano eruption, the liquid is then called…. . LAVA! § Lava flows down the side of the volcano after it erupts

Examples of Igneous Rocks

Obsidian § Obsidian is nature’s glass § It forms when lava cools quickly on the Earth’s surface § It has been used by many Native American cultures to make arrowheads and blades.

Pumice § Pumice is full of air pockets! § The air pockets were trapped when the lava frothed and foamed out onto the Earth’s surface and cooled § Because of the air pockets, it is the only rock that…. ?

Floats!!

Porphyry

Lava Rock

All About Sedimentary Rocks!

How are sedimentary rocks formed? § Rain, the freeze/thaw cycle, wind, & running water cause igneous rocks to crumble a little bit at a time. § Erosion and weathering cause the sediments from igneous rocks to wash into bodies of water

Igneous rock sediments washing into a body of water

How Sedimentary Rocks are Formed continued § Over many years, layers of different rock settle at the bottom of bodies of water § Eventually the layers of sand mud at the bottom of these bodies of water turn into sedimentary rock through compaction and cementation

Example of how sedimentary rocks are formed

Fun and Interesting facts about sedimentary rocks § It is easy to see which rock layer in a mountain is oldest § The sequence (order) of rock layers from top to bottom corresponds (matches) to the youngest and oldest rocks § Sedimentary rocks cover 75% of the Earth’s surface! § Can you guess what is often found in sedimentary rocks?

Animal & plant fossils! § Animals and plants that have died get covered up by new layers of sediment and are turned into stone within the rock!

Examples of Sedimentary rock

Crinoid

Alabaster

Sandstone

All About Metamorphic Rock!

What does Metamorphic mean? § The word metamorphic comes from the Greek words “Meta” and “Morphic” which mean to change form § Metamorphic rocks are rocks that have changed their form

How are Metamorphic rocks formed? § Metamorphic rocks were originally igneous and sedimentary rocks, but due to the movement of the Earth’s crust and extreme heat and pressure they changed form.

How are metamorphic rocks formed continued § Igneous and sedimentary rocks are subjected (put under) to so much heat and pressure within the Earth’s crust that profound (intense) physical and chemical changes occur to the rock. § Temperatures within the Earth’s crust get to be 302 to 392 degrees

How are metamorphic rocks formed continued § When the Earth’s crust moves, it causes rocks to get squeezed so hard and heated so much that it causes the rocks to change § So basically, any rock that changes into another rock is called…?

Metamorphic! § Under the right conditions, any type of rock can become another type of rock. § Did you know that metamorphic rocks are the least common type of the three types of rock?

Examples of Metamorphic Rock

Schist

Gneiss

Marble § For Your Information: This is Alabama’s state rock!

What are some “Big Idea” Inferences or Conclusions we can make about the rock cycle? § All rocks relate to each other within the big picture of the Earth’s continuously changing surface § The rock cycle is a concept that puts the classifications of Igneous, sedimentary, and metamorphic rocks together into one gigantic “rock recycling” process that is continually going on in and on the Earth’s surface.

What are some “Big Idea” Inferences or Conclusions we can make about the rock cycle continued § Different types of cycles keep the living and non-living factors on the Earth’s surface in check with each other. § These cycles keep the relationships among those factors in a healthy perspective with each other

How are we as humans affected by Earth’s changing surface? § We must understand that the Earth’s changing surface is a continual cycle that will always impact our lives. § The changes on the Earth’s surface affect our lives and the lives of animals and plants. § The changes can often be deadly and/or costly to our society. § We must be knowledgeable about all the types of changes on the Earth’s surface so that we can make informed decisions about everyday life.

That’s the End of our Rock Cycle Unit! http: //www. phschool. com/atschool/phsciexp/active_art /rock_cycle/index. html