8.12.1-Rocks & the Rock Cycle

Rocks

Rocks are everywhere. Mountains, valleys, and the seafloor are made of rocks. Parts of your home are likely made of rock. Floors, countertops, and some tabletops are made of rock. A rock is a natural, solid mixture of minerals or grains. These particles are made of mineral crystals, broken minerals, or rock fragments. Sometimes a rock can also include remains of an organism or volcanic glass. Processes on Earth’s surface can cause rocks to break apart into fragments. Geologists call the fragments that make up a rock grains. Grains are identified according to the grain’s shape, size, and chemical composition. Overall, rocks are classified according to their texture and composition.

Multiple Choice

Grains are identified according to their

• size

• shape

• Chemical composition

• all of the above

Multiple Choice

Which one of these are particles in rocks NOT made of

• mineral crystals

• Broken Minerals

• synthetic diamonds

• rock fragements

​Two observations Scientists use #1

​A rock’s texture is one way that geologists classify rocks. The grain size and the way grains fit together in a rock are called texture. When a geologist classifies a rock by its texture, he or she looks at the size of minerals or grains in the rock, the arrangement of the individual grains, and the overall feel of the rock. Texture helps geologists determine the environment in which a rock formed. For example, a rock that has many smooth grains was likely formed by strong forces acting on the rock.

Multiple Choice

texture helps geologists determine the _______ in which a rock formed

• environment

• laboratory

• volcano

• planet

​Two observations scientists use #2

​The second thing scientists use to classify a rock is its composition. This is the type of grains that makeup a rock. Rocks that formed inside a volcano have a different composition from rocks that formed along a river. Geologists use maps, field journals, compasses, rock hammers, and other tools to help classify a rock’s texture and composition. These tools also help geologists interpret how a rock formed. When geologists identify certain minerals, they can conclude that a rock formed under extreme temperature and pressure. The presence of other minerals suggests to geologists that a rock formed from molten material deep below Earth’s surface.

Multiple Choice

A rocks composition can help scientists

• decide where the rock was made in a lab

• decide where the rock formed in nature

• get rich

• find other rocks

​Three major rock groups

​Rocks are classified, or placed into groups, based on how they form. The three major groups are igneous rocks, sedimentary rocks, and metamorphic rocks. Each rock type can be described by both physical and chemical characteristics. Geologists interpret the environment in which the rocks formed based on these characteristics.

​Igneous Rocks

Igneous rocks form from magma. Magma is molten, or liquid, rock underground. As the magma, or molten rock cools, mineral crystals form. These crystals become the grains in an igneous rock. Magma can cool on Earth’s surface or deep within Earth. Molten rock that erupts on Earth’s surface is called lava. Igneous rock forms when the magma or lava cools and crystallizes. Igneous rock forms in many environments, such as subduction zones, mid-ocean ridges, and around hot spots where volcanoes are common.

Multiple Choice

Molten rock that erupts ON earths surface is called

• magma

• lava

• ro

• crystals

Multiple Choice

Igneous rocks often form near ________, mid ocean ridges, and hot spots

• villages

• subduction zones

• fields

• in caves

​Sedimentary Rocks

​Rocks on Earth’s surface can break down and be transported to new environments by 4 main forces. Wind, running water, ice, and gravity break down rocks on Earth’s surface.

​

Sediment is rock material that forms where rocks are broken down into smaller pieces or dissolved in water as rocks erode. These materials are the building blocks of sedimentary rocks and include rock fragments, mineral crystals, and the remains of certain plants and animals. Sedimentary rocks form where sediment is deposited. Environments in which sedimentary rocks are formed include rivers, streams, mountain valleys, and deserts.

Multiple Choice

Wind, _____, ice, and gravity break down rocks

• tornadoes

• still water

• sleet

• running water

​Metamorphic Rocks

​Metamorphic rocks form when preexisting rocks are exposed to extreme temperatures, extreme pressure, or chemical fluids. This causes changes to both the composition and texture of the rock.

​

In many cases, the grains of the rock appear as bent or twisted layers. Metamorphic rocks can form from any igneous or sedimentary rock. Even other metamorphic rocks can be formed into new metamorphic rocks by extreme conditions. For example, granite is an igneous rock. It can metamorphose, or change, into gneiss. The sedimentary rock limestone can metamorphose into marble. Metamorphic rock often forms along plate boundaries, where extreme temperatures and intense pressure occur.

Multiple Choice

Which example of igneous rock did I just give

• gneiss

• topaz

• granite

• magma

​The Rock Cycle

​Rocks are changing all the time, although you can’t usually observe these changes. The series of processes that change one type of rock into another type of rock is called the rock cycle. Forces on Earth’s surface and deep within Earth drive the rock cycle. The cycle describes how natural processes work to change one rock type into another rock type. One example is igneous rock that begins as lava. The lava cools and crystallizes. Over time, water erodes this rock to form sediments that eventually cement together to become sedimentary rock. Some of the other processes rocks go through include melting, cooling and crystallization, heat and pressure, compaction and cementation, and erosion and deposition. There is no true beginning or end to the rock cycle.

Multiple Choice

Which is the beginning of the rock cycle?

• se

• Igneous

• metamorphic

• There is none

Multiple Select

How are rocks classified? (Select 2)

• Color

• Composition

• Texture

• Shape

Multiple Select

What are the three classes of rock? (Select 3)

• Sedimentary

• Lava

• Metamorphic

• Magma

• Igneous

Multiple Choice

What size crystals form when magma cools slowly inside the Earth?

• Small

• Medium

• Large

Multiple Choice

What are rocks that cool inside the Earth called?

• Extrusive Igneous

• Intrusive Sedimentary

• Intrusive Igneous

• Extrusive Metamorphic

Multiple Choice

What size crystals form when lava cools quickly outside the Earth?

• Small

• Medium

• Large

Multiple Choice

What are rocks that cool outside the Earth called?

• Extrusive Igneous

• Intrusive Sedimentary

• Intrusive Igneous

• Extrusive Metamorphic

Multiple Select

What do scientists use to name sedimentary rocks? (Select 2)

• Size of sediment

• Color of rock

• Type of rock

• Color of sediment

Multiple Choice

What process causes sedimentary rock to form?

• Melting

• Heat and Pressure

• Weathering and Erosion

• Weight pressing layers of sediment together

Multiple Choice

What processes causes metamorphic rock to form?

• Melting

• Heat and Pressure

• Weathering and Erosion

• Weight pressing layers of sediment together

Multiple Select

What kind of rocks did metamporhic rocks start out as? (Select 2)

• Magma

• Sedimentary

• Lava

• Igneous

Multiple Choice

Any rock can change into any other kind of rock.

• True

• False

Match

Match the following terms and definitions.

• Weathering

• Sediment

• Erosion

• Deposition

Wind, water, ice, & temp break down rock

Rock fragments created by weathering

Moving sediment from 1 place to another

Sediment ending up in water or low areas

• Wind, water, ice, & temp break down rock

• Rock fragments created by weathering

• Moving sediment from 1 place to another

• Sediment ending up in water or low areas

Multiple Choice

This rock was another type of rock that was heated and compressed over time. What type of rock is this?

• Sedimentary

• Igneous

• Metamorphic

Multiple Choice

This rock started as molten magma but transformed after a volcano erupted. What type of rock is this?

• Sedimentary

• Igneous

• Metamorphic

Multiple Choice

This rock was formed by smaller pieces of rock that settled at the bottom of a lake millions of years ago. What type of rock is this?

• Sedimentary

• Igneous

• Metamorphic

Multiple Choice

The process when rocks break into smaller pieces due to exposure to natural elements is called...

• Deposition

• Erosion

• Weathering

Multiple Choice

The process by which sediments move from one place to another from wind or rain is called...

• Deposition

• Erosion

• Weathering

Multiple Choice

The process where material is added to land (or a landform). Can be deposited by water, wind or glaciers.

• Deposition

• Erosion

• Weathering

Multiple Choice

What are the 3 major types of rocks?

• Igneous, Sedimentary, Metamorphic

• Metamorphic, Igneous, Cementation

• Magma, Lava, Crystals

• Air, Water, Earth, Fire

Multiple Choice

The process by which metamorphic rocks are formed...

• Erosion and Deposition

• Heat and Pressure

• Melting and Cooling

Multiple Choice

What do we call the material that comes from rocks that have been broken down into smaller pieces?

• Texture

• Weathering

• Sediment

• Erosion

Multiple Choice

What causes igneous rocks to form?

• Erosion and Weathering

• Cooling of magma or lava

• Heat and Pressure

Multiple Choice

Molten rock below the Earth's surface is called...

• Magma

• Lava

• Goo

• Really hot goo

Multiple Choice

Molten rock above the Earth's surface is called...

• Magma

• Lava

• Goo

• Really hot goo

Multiple Choice

What are the remains of plants or animals preserved in petrified form or as impressions made in rock?

• Crystals

• Fossils

• Geodes

Multiple Choice

Which type of rock are fossils found in?

• Igenous

• Sedimentary

• Metamorphic

Multiple Choice

Any rock can turn into any other kind of rock.

• True

• False

3 main types of rocks

• Igneous

• Sedimentary

• Metamorphic

Igneous rocks: forms from the cooling of molten rock (magma or lava)

• Extrusive Rock – igneous rock formed from lava that erupted onto Earth’s surface; basalt is the most common extrusive rock

• Intrusive Rock – igneous rock that formed when magma hardened beneath Earth’s surface; granite is the most common intrusive rock

• Texture – depends on the size and shape of the mineral crystals  Fine-grained – rapid cooling Glassy – rapid cooling Coarse, large, or medium grained – slow cooling; the slower magma cools, the larger the crystals

Sedimentary rock – forms when particles of other rocks or the remains of plants and animals are pressed and cemented together

• Processes that turn sediment to rock

• Weathering – breaks rock down into sediment

• Erosion – moving of sediment to a new location

• Deposition – dropping of sediment

• Compaction – presses sediment together

• Cementation – dissolved minerals crystallize and glue particles of sediment together 

Types of Sedimentary Rocks

• Clastic – a sedimentary rock that forms when rock fragments squeeze together like shale, sandstone and conglomerate

• Organic – forms when layers of plants and animals are deposited in thick layers like coal and limestone

• Chemical – form when minerals that are dissolved in a solution crystallize or from mineral deposits that are left when seas or lakes evaporate like rock salt

• 
  

• 
  

• 
  

Metamorphic rock – formed when an existing rock is changed by heat and/or pressure

• Foliated – grains arranged in parallel layers or bands like slate, schist and gneiss

• Nonfoliated – mineral grains are arranged randomly like marble and quartzite

• 
  

Rock Cycle

- forces inside the Earth and at the surface produce a rock cycle that builds, destroys, and changes the rock in the crust; the series of processes on and beneath Earth’s surface that slowly change rocks from one kind to another

Any rock can change into another type of rock; rocks of the same type can turn into a new rock of that type

Multiple Choice

What type of rock has undergone changes in chemical or physical form?

• sedimentary rock

• metamorphic rock

• igneous rock

Multiple Select

What type of rock can turn into metamorphic rock?

• metamorphic rocks

• sedimentary rocks

• igneous rocks

Multiple Choice

When rock change from one form to another is called  the _________.

• Rock Circle

• Rock Tranformation

• Rock Exchange

• Rock Cycle

Rocks and The Rock Cycle

Watch the following video then answer the questions that follow

Multiple Choice

How old are most rocks on Earth today?

• 1 million years old

• 100 million years old

• 10 million years old

• 1 billion years old

Multiple Choice

Are rocks are naturally occuring?

• Yes

• No

Poll

What are the three main classes of rock?

• igneous

• metamorphic

• sedimentary

• granite

• sediments

​The three main types of rocks are ...

• ​igneous

• sedimentary

• ​metamorphic

Multiple Choice

Which rock is formed when magma or lava cools down?

• metamorphic rocks

• limestone rock

• sedimentary rocks

• igneous rocks

Multiple Choice

What type of igneous rock is form when mago cools down slowly inside the earth?

• extrusive igneous rock

• intrusive igneous rock

Multiple Choice

When magma cools slowly _________ crystals form.

• small

• no

• large

• very few

Multiple Choice

What type of rock is formed from lava cooling down?

• extrusive igneous rock

• intrusive igneous rock

• coal

• granite

Multiple Choice

Because extrusive igneous rock cools quickly ________ chrystals form.

• large

• very few

• small

• no

Multiple Choice

When rocks are broken down into small pieces by wind, air, water, ice or gravity?

• erosion

• transported

• weathering

• deposition

Multiple Choice

What rock type is formed when layers of sediment are compress by gravity and cemented together?

• igneous rock

• obsidian rock

• metamorphic rock

• sedimentary rock

Multiple Choice

The deposit of sediment in bodies of water over long periods of time will form ____________.

• metamorphic rock

• sedimentary rock

• igneous rock

Multiple Choice

What type of rock has undergone changes in chemical or physical form?

• sedimentary rock

• metamorphic rock

• igneous rock

Multiple Select

What type of rock can turn into metamorphic rock?

• metamorphic rocks

• sedimentary rocks

• igneous rocks