Earth's Surface and Systems

Earth's Surface and Systems

Middle School

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Learning Objectives

• Describe the key processes of weathering, erosion, and deposition on Earth's surface.

• Explain how water, wind, ice, and gravity act as agents of change.

• Explain how Earth's surface changes over both short and long periods of time.

• Connect different landforms to the geological processes that created and shaped them.

Key Vocabulary

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Weathering

Weathering is the process of breaking down rock and other materials on the Earth's surface.

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Erosion

Erosion is the movement of broken rock particles by natural forces like wind, water, ice, or gravity.

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Deposition

Deposition is the process of dropping or laying down sediment in a new location after being moved.

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Geoscience Process

A geoscience process is any natural process that is responsible for changing the surface of the Earth.

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Spatial Scale

Spatial scale refers to the size of an area something affects, from microscopic to a global level.

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Temporal Scale

Temporal scale refers to how long a process takes, from seconds to millions or billions of years.

Key Vocabulary

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Catastrophic Event

A sudden, widespread event that causes rapid and significant change to the Earth's surface.

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Plate Tectonics

The scientific theory that describes the large-scale motion of Earth's lithosphere plates.

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Soil

The loose, weathered material on Earth's surface in which plants can grow well.

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Humus

Dark, organic material in soil that is formed from decayed plants and animals.

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Glacier

A very large body of ice that moves slowly down a slope or valley.

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Mass Movement

The downhill movement of rock, soil, and other debris because of the force of gravity.

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Scales of Change in Geoscience

• Geoscience processes shape Earth’s surface on different time and size scales.

• ​Some changes, like moving tectonic plates, happen slowly over millions of years.

• Other events, such as landslides, can change the landscape very rapidly.

• Processes range from tiny, like dissolving minerals, to large-scale, like forming continents.

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Multiple Choice

What is the main characteristic of the geoscience processes that shape Earth's surface?

• They occur on different time and size scales.

• They only happen very slowly over millions of years.

• They only include large events like forming continents.

• They are always completed within a single year.

Multiple Choice

What is the primary difference between the movement of tectonic plates and a landslide?

• The speed at which they change the landscape.

• The type of climate in which they occur.

• The amount of water they involve.

• The time of day they happen.

Multiple Choice

Which pair of events best illustrates the full range of both time and size scales in geoscience processes?

• A large continent forming slowly and a tiny mineral dissolving quickly.

• A mountain forming slowly and a tectonic plate moving slowly.

• A landslide happening quickly and an earthquake happening quickly.

• A small rock breaking apart and a small pebble eroding.

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Plate Tectonics: Shaping the Earth

• The Earth's crust is broken into large pieces called tectonic plates.

• These plates are in constant, slow motion over millions of years.

• When plates collide, they can push up to form huge mountain ranges.

• When plates separate, they can form new oceans over long periods.

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Multiple Choice

Which statement best defines tectonic plates?

• Large pieces of the Earth's crust that are in slow, constant motion.

• The heat that comes from the Earth's core.

• The oceans that are formed between continents.

• The mountains that are created by volcanoes.

Multiple Choice

What is the relationship between the movement of tectonic plates and the Earth's features?

• The movement of plates can form mountains or oceans.

• The movement of plates causes the Earth to spin faster.

• The movement of plates only happens deep in the oceans.

• The movement of plates is too fast for humans to see.

Multiple Choice

Geologists discover a location where two tectonic plates are slowly moving toward each other. Based on this evidence, what can be predicted about this location millions of years in the future?

• A large mountain range will likely form in that location.

• A new ocean will likely form in that location.

• The plates will stop moving and become stable.

• The Earth's crust will become thinner in that area.

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Weathering: Breaking Down Rocks

Mechanical

• Rock is physically broken into smaller pieces without any chemical changes occurring.

• The main causes are the freezing and thawing of water, also known as frost wedging.

• Other causes include pressure release, plant root growth, animal actions, and abrasion.

Chemical

• This process breaks down rock through chemical reactions, creating entirely new minerals.

• The main agents that cause these changes are water, oxygen, and carbon dioxide.

• Living organisms, such as lichens, and acid rain also contribute to chemical weathering.

Multiple Choice

What is the primary difference between mechanical and chemical weathering?

• Mechanical weathering involves physical force, while chemical weathering involves chemical reactions.

• Mechanical weathering only happens in cold climates, while chemical weathering only happens in warm climates.

• Mechanical weathering is caused by plants, while chemical weathering is caused by water.

• Mechanical weathering makes rocks smaller, while chemical weathering makes rocks disappear.

Multiple Choice

Which process is an example of chemical weathering?

• A rock cracking as a plant's roots grow larger.

• A rock breaking apart from the pressure of freezing water.

• Lichens on a rock's surface creating weak acids that dissolve it.

• A rock being worn smooth by the scraping of other rocks.

Multiple Choice

A scientist observes that a rock has not only broken into smaller pieces but has also formed new, rust-colored minerals on its surface. What is the most likely explanation for this change?

• The rock was broken apart by the physical action of animal burrowing.

• The rock underwent chemical weathering due to a reaction with oxygen.

• The rock was split apart by the release of internal pressure.

• The rock was worn down by abrasion from wind and water.

How Soil is Formed

• Soil is a mix of rock particles, water, air, and organic matter.

• It develops in layers called horizons over hundreds of years.

• Organisms like worms and bacteria help create and mix the soil.

Multiple Choice

What is soil?

• A mixture of rock particles, organic matter, air, and water

• Layers of solid rock deep beneath the ground

• Only the water and air found underground

• Just the dead plants and animals on the surface

Multiple Choice

What is the primary role of organisms like worms and bacteria in the soil formation process?

• They help to create and mix the soil components.

• They turn rock particles directly into the air.

• They prevent water from entering the soil.

• They form the solid rock layers called horizons.

Multiple Choice

If a barren, rocky area had no living organisms, what could you predict about the process of soil formation?

• The soil would likely form much more slowly.

• The soil would form much more quickly.

• The rock particles would not be able to form.

• The soil would contain more water than usual.

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Erosion & Deposition: Gravity and Wind

Mass Movement

• Gravity pulls rocks and soil downhill in a process called mass movement.

• Landslides and mudflows are very fast, while creep is a much slower movement.

• These events can change the shape of a landscape very quickly or gradually.

Wind Action

• Wind erodes land by lifting loose particles and sandblasting rock surfaces.

• When the wind slows, it deposits the sediment it has been carrying.

• This process forms features like large sand dunes and rich loess deposits.

Multiple Choice

What is mass movement?

• The process where gravity pulls rocks and soil downhill.

• The process where wind lifts and carries loose particles.

• The formation of large sand dunes from wind.

• The slow and gradual movement of ice in a glacier.

Multiple Choice

What is the relationship between wind speed and the formation of sand dunes?

• The wind slows down, causing it to drop the particles it was carrying.

• The wind speeds up, allowing it to pick up more particles.

• The wind hits a large rock surface, causing sandblasting.

• The particles become heavier, making them harder for the wind to carry.

Multiple Choice

After several days of heavy rain on a steep mountain, a large area of the hillside suddenly collapses and slides into the valley below. Which statement best explains this event?

• A landslide, because it is a rapid downhill movement of soil and rock.

• Creep, because the landscape is changing gradually over time.

• Wind erosion, because loose particles are being lifted from the surface.

• A loess deposit, because rich soil is being formed by the wind.

Erosion & Deposition: Moving Water

• Runoff from rain and snow erodes land, forming streams and rivers.

• Slow-moving water deposits sediment, forming deltas and alluvial fans.

• Groundwater can dissolve rock, creating large underground caves over time.

Multiple Choice

What process is responsible for the formation of streams and rivers?

• The erosion of land by water runoff

• The dissolving of rock by groundwater

• The deposition of sediment in one place

• The freezing and thawing of water in cracks

Multiple Choice

What happens to the sediment in a river when the water's movement slows down?

• It gains speed and causes more erosion.

• It deposits the sediment it is carrying.

• It begins to dissolve underground rock.

• It evaporates more quickly.

Multiple Choice

Which of the following features would provide the best evidence that groundwater erosion, rather than surface water runoff, has occurred in an area?

• The formation of a river delta.

• The presence of a wide, winding river.

• The presence of large underground caves.

• The creation of an alluvial fan at a canyon's base.

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Erosion & Deposition: Ice and Waves

Shaped by Ice

• A glacier, a huge mass of moving ice, carves the land by pulling and scraping away rock.

• This powerful carving action by the ice is what creates very wide, U-shaped valleys in the landscape.

• As a glacier melts, it leaves behind a mix of sediment called till, forming ridges called moraines.

Shaped by Waves

• The constant force of waves crashing against the shore erodes the land, forming features like sea caves.

• Waves also move and deposit sediment, such as sand, along the coastline in a process called longshore drift.

• This deposition of sediment is responsible for building up landforms like beaches and long barrier islands.

Multiple Choice

What are the two main processes by which ice and waves shape and change the land?

• Erosion and deposition

• Melting and freezing

• Scraping and crashing

• Heating and cooling

Multiple Choice

How do the landforms created by glacial deposition differ from those created by wave deposition?

• Glaciers leave behind ridges of till called moraines, while waves build up landforms like beaches.

• Glaciers carve wide, U-shaped valleys, while waves form sea caves.

• Glaciers deposit sediment in a process called longshore drift, while waves scrape away rock.

• Glaciers create barrier islands, while waves create wide valleys.

Multiple Choice

If a coastal area begins to experience much stronger waves but receives less sand from longshore drift, what is the most likely outcome?

• The coastline will likely wear away, and existing sea caves may become larger.

• The beaches along the coast will become much wider.

• The coastline will be carved into a U-shaped valley.

• A large moraine will be left behind on the shore.

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Catastrophic Events: Rapid Change

• Catastrophic events cause sudden, large-scale, and rapid changes to the Earth’s surface.

• ​These events can create or change landforms in just minutes or hours.

• Examples include volcanic eruptions, earthquakes, and meteor impacts that alter the landscape.

• Later, slower processes like weathering and erosion reshape these new landforms over time.

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Multiple Choice

What is the primary effect of a catastrophic event on the Earth's surface?

• They cause slow and gradual changes over millions of years.

• They only affect the Earth's oceans and atmosphere.

• They are natural processes that are always predictable.

• They cause sudden and large-scale changes to the Earth's surface.

Multiple Choice

What is the relationship between an event like a meteor impact and a landform?

• They can create new landforms in a very short amount of time.

• They only cause changes that are too small to see.

• They prevent slower processes like erosion from happening.

• They gradually wear down mountains over thousands of years.

Multiple Choice

After a catastrophic event like a volcanic eruption forms a new mountain, what is the most likely long-term outcome for this landform?

• The new landform will be slowly reshaped by weathering and erosion.

• The new landform will likely be destroyed by another earthquake within a week.

• The new landform will remain unchanged for millions of years.

• The new landform will prevent any further changes to the landscape.

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Common Misconceptions

Misconception	Correction
Weathering and erosion are the same thing.	Weathering breaks rocks. Erosion moves the broken pieces.
Changes to Earth's surface always take millions of years.	Quick events like landslides and volcanic eruptions can also change the surface.
A landform is created by a single event.	Most landforms are the result of multiple processes.

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Summary

• Geoscience processes change Earth's surface at various time and spatial scales.

• Slow processes like plate tectonics build mountains, while weathering and erosion reshape land.

• Rapid, catastrophic events like volcanoes and earthquakes can dramatically alter the surface.

• Surface features and soil result from a combination of these different processes.

Poll

On a scale of 1-4, how confident are you about explaining how various geoscience processes shape the Earth's surface?

• 1

• 2

• 3

• 4