Mountains and Metamorphic Rocks

Mountains and Metamorphic Rocks

Middle School

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Learning Objectives

• Describe the cycling of Earth's materials and the flow of energy that drives it.

• Explain how lithospheric plate movement, driven by internal energy, forms mountain ranges.

• Describe how heat and pressure from Earth's interior create metamorphic rocks.

• Explain how weathering and erosion, driven by the sun, change and shape landforms.

• Model the rock cycle, explaining how any rock can change into another type.

Key Vocabulary

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Geosphere

The geosphere is the solid part of Earth, which includes all rocks, landforms, the crust, and the underlying mantle.

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Lithosphere

The lithosphere is the rigid, rocky outer layer of the Earth, consisting of the crust and the solid upper mantle.

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Asthenosphere

The asthenosphere is a semi-fluid layer in the upper mantle, located just beneath the rigid lithosphere on which plates float.

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Plate Tectonics

Plate tectonics is the scientific theory that Earth's outer shell is divided into several large plates that slowly move.

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Subduction

Subduction is the geological process where one tectonic plate slides underneath another plate and sinks into the mantle.

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Metamorphic Rock

Metamorphic rock is a type of rock that has been completely changed by intense heat and pressure within the Earth.

Key Vocabulary

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Rock Cycle

The rock cycle describes the series of processes that are responsible for creating and transforming rocks.

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Foliation

Foliation is the parallel alignment of minerals within a metamorphic rock, giving it a layered appearance.

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Deformation

Deformation refers to the change in a rock's original shape, which is caused by geological stress.

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Crystallization

Crystallization is the process of forming solid crystals as atoms arrange themselves in an ordered structure.

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Weathering

Weathering is the process that breaks down rocks and minerals through contact with the Earth's atmosphere.

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Sedimentation

Sedimentation is the process where rock particles settle and are deposited in a new location.

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Earth's Systems and Layers

• Earth has four interconnected systems: geosphere, hydrosphere, atmosphere, and biosphere.

• The geosphere has a solid crust, a partly fluid mantle, and a metallic core.

• The lithosphere is the crust and the solid upper part of the mantle.

• This lithosphere floats on a fluid part of the mantle called the asthenosphere.

Multiple Choice

Which of Earth's four systems is primarily composed of land and the planet's physical structure?

• The geosphere

• The hydrosphere

• The atmosphere

• The biosphere

Multiple Choice

Which statement best describes the composition of the lithosphere?

• It is composed of the crust and the solid upper part of the mantle.

• It is the fluid layer that exists deep within the core.

• It is made up of only the Earth's crust and oceans.

• It is the layer of air surrounding the Earth.

Multiple Choice

Based on the relationship between Earth's layers, what would be the most likely consequence if the asthenosphere were solid instead of fluid?

• The lithosphere would not be able to 'float' and move.

• The Earth's core would become much hotter.

• The atmosphere would mix with the hydrosphere.

• The biosphere would not be able to support life.

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Energy Driving Earth's Processes

• All Earth's processes are driven by energy from the sun and Earth's interior.

• ​The sun's energy drives surface processes like the movement of water and wind.

• This movement of water and wind causes the weathering and erosion of rocks.

• Heat from Earth's interior melts, deforms, and crystallizes rock, moving tectonic plates.

Multiple Choice

What is the primary source of energy for most processes that happen on Earth's surface?

• Energy from the sun

• Energy from Earth's interior

• Energy from the movement of water

• Energy from the movement of wind

Multiple Choice

What is the relationship between solar energy and the erosion of rocks?

• It causes the movement of water and wind, which wears away rocks.

• It directly melts the surface of rocks, causing them to break.

• It helps new types of rock crystallize on the surface.

• It pushes tectonic plates together, which breaks up surface rocks.

Multiple Choice

Which of the following major Earth process is powered by energy from the planet's hot interior?

• The movement of tectonic plates

• The erosion of a coastline by waves

• The weathering of a mountain by a glacier

• The formation of clouds in the atmosphere

Moving Tectonic Plates

• The lithosphere is broken into large slabs called lithospheric plates that constantly move.

• Energy from the Earth's interior drives this movement, creating a "slab pull."

• These forces cause plates to move and interact with each other at boundaries.

Multiple Choice

What are lithospheric plates?

• Large, constantly moving slabs that make up the lithosphere.

• Stationary continents that do not move.

• Layers of molten rock found in the Earth's core.

• Currents of water flowing in the deep ocean.

Multiple Choice

What provides the force that drives the movement of lithospheric plates?

• The gravitational pull of the Moon.

• The spinning of the Earth on its axis.

• Energy from the Earth's interior.

• Heat from the Sun warming the planet's surface.

Multiple Choice

Which statement best summarizes the process described?

• The movement of lithospheric plates is the primary source of the Earth's internal energy.

• Energy from within the Earth causes slabs of the lithosphere to move and interact at their boundaries.

• Interactions at plate boundaries stop the flow of energy from the Earth's interior.

• The lithosphere is a single, unbroken slab that is heated by the Earth's core.

Constructive Forces: Mountain Building

• Constructive processes build up landforms like mountains.

• Two continental plates colliding can form huge mountain ranges.

• Volcanoes form when an oceanic plate subducts under a continental plate.

Multiple Choice

What is the primary function of a constructive process?

• To build up landforms on the Earth's surface

• To break down and wear away existing landforms

• To cause earthquakes and tsunamis

• To create new oceans between continents

Multiple Choice

How are vast mountain ranges formed?

• When two continental plates collide with each other

• When an oceanic plate sinks under a continental plate

• When two continental plates slide past each other

• When two continental plates pull apart from each other

Multiple Choice

If an oceanic plate is observed moving toward and sinking under a continental plate, what is the most probable geological outcome?

• A volcano will likely form on the continent.

• A new mountain range will form in the ocean.

• The two plates will stop moving.

• The continent will split into two parts.

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Destructive Forces and Surface Changes

• Destructive forces are responsible for wearing down Earth's surface features over time.

• Weathering is the process that breaks large rocks into much smaller pieces.

• Erosion transports these broken pieces of rock by water, ice, and wind.

• These processes can create canyons or wear down mountains over millions of years.

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Multiple Choice

What is the primary role of destructive forces on Earth's surface?

• They build up new landforms like mountains.

• They wear down existing surface features over time.

• They cause sudden events like earthquakes.

• They create new water sources on the planet.

Multiple Choice

What is the relationship between weathering and erosion?

• Weathering is caused by water, while erosion is caused by wind and ice.

• Weathering breaks rocks into smaller pieces, while erosion carries those pieces away.

• Weathering happens to mountains, while erosion happens in canyons.

• Weathering is a fast process, while erosion is a slow process.

Multiple Choice

If a large, steep mountain is exposed to constant wind and flowing water for millions of years, what is the most likely outcome?

• The mountain would become taller as new rock is pushed up from below.

• The mountain would remain unchanged because rocks are too hard to be affected by wind and water.

• The mountain would become lower and more rounded as rock pieces are broken down and carried away.

• The mountain would develop deep caves but its overall height would not change.

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What is a Metamorphic Rock?

• A metamorphic rock forms when existing rock changes solidly without ever melting.

• Deep burial supplies great heat that rearranges minerals inside the rock over time.

• Heavy layers above create crushing pressure that squeezes and compacts the buried rock.

• Moving tectonic plates fold, stretch, and deform rocks, adding extra force during metamorphism.

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Multiple Choice

What is the defining characteristic of a rock undergoing metamorphism?

• It melts completely into magma.

• It breaks down into small pieces of sediment.

• It changes into a new rock without melting.

• It gets lifted up to the Earth's surface.

Multiple Choice

What relationship explains how metamorphic rocks are formed?

• Melting from a volcano and cooling from water.

• Weathering from wind and erosion from rivers.

• Heat from deep burial and pressure from overlying rocks.

• Compaction of sand and cementation of shells.

Multiple Choice

If a large section of rock is subjected to the immense force of two colliding tectonic plates, what is the most probable geological outcome for that rock?

• The rock will melt into magma due to the intense force.

• The rock will be completely unaffected by the tectonic plate movement.

• The rock will likely be deformed and its minerals rearranged by the intense force.

• The rock will be instantly weathered into sand and clay.

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Features of Metamorphic Rocks

• Metamorphism can make rocks harder through a process called recrystallization.

• ​For instance, soft sandstone transforms into the much harder rock quartzite.

• Pressure rearranges minerals into layers or bands, a feature called foliation.

• Contact with hot magma can bake and alter the surrounding rock.

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Multiple Choice

What is the process that can make metamorphic rocks harder?

• Foliation

• Recrystallization

• Contact

• Layering

Multiple Choice

Which statement best describes the relationship between sandstone and quartzite?

• Sandstone is a layered version of quartzite.

• Quartzite is a harder rock that forms from the alteration of sandstone.

• Sandstone and quartzite are both soft rocks created by pressure.

• Quartzite forms when sandstone is baked by magma.

Multiple Choice

If a rock is subjected to both intense pressure and contact with hot magma, what two features is it most likely to develop?

• Softness and a uniform, non-layered texture

• Hardness and foliation (mineral layers)

• The properties of a liquid rock or magma

• A baked texture with no signs of pressure

The Rock Cycle

• Magma or lava cools and crystallizes to form igneous rocks.

• Weathering and erosion create sediments that form sedimentary rocks.

• Heat and pressure transform existing rocks into metamorphic rocks.

Multiple Choice

Which process leads to the formation of igneous rocks?

• The cooling and crystallization of magma or lava

• The compaction and cementation of sediments

• The application of heat and pressure to existing rocks

• The breakdown of rocks by wind and water

Multiple Choice

What is the relationship between weathering, erosion, and sedimentary rocks?

• Weathering and erosion create the sediments that form sedimentary rocks.

• Sedimentary rocks are weathered and eroded to form magma.

• Weathering and erosion apply heat and pressure to form sedimentary rocks.

• Sedimentary rocks are melted by the process of weathering and erosion.

Multiple Choice

A layer of sedimentary rock is buried deep beneath the Earth's surface and is subjected to intense heat and pressure. What type of rock will it most likely become?

• Metamorphic rock

• Igneous rock

• A new layer of sediment

• Magma

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Common Misconceptions

Misconception	Correction
Metamorphic rocks are rocks that melted and cooled again.	Metamorphism is change by heat and pressure, without the rock melting.
Mountains are permanent and unchanging.	Mountains are constantly built up and worn down by erosion.
Geological changes are always slow.	Changes can be rapid, like earthquakes, volcanic eruptions, and landslides.
The rock cycle is a simple, one-way circle.	The rock cycle is a complex web, not a simple one-way circle.

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Summary

• Earth's processes are driven by internal heat and energy from the sun.

• Constructive forces build landforms, and destructive forces break them down.

• Heat and pressure form harder, often layered metamorphic rocks.

• The rock cycle shows how rocks change over slow and rapid timescales.

Poll

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