Tag: geology

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Earthquakes & Plate Tectonics: a guide to causes, magnitude, epicenters, and more

earthquake diagrams showing an epicenter, focus, fault scarp, ruptured fault, and more.
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In this post, you’ll read about why and where earthquakes happen. Learn how scientists measure earthquakes and what the “magnitude” of an earthquake actually means and what an “epicenter” is. You’ll discover the connection between earthquakes and the theory of plate tectonics, and learn about the boundary types along which severe earthquakes most commonly occur.

For Teachers: If you’re an educator planning to teach earthquakes or plate boundary movement, great learning resources are key to deepening understanding! I think you and your students will love my complete Plate Tectonics Unit. The information and images in this post come from the unit, and the unit is also packed with diagrams, readings, and activities covering earthquakes, volcanoes, Earth’s layers, boundary types, and more (plus you’ll support my blog with your purchase! ❤️)

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What is an earthquake?

An earthquake is ground shaking caused by a sudden release of energy stored within the crust. This energy is supplied by plate tectonic forces. Ground shaking during earthquakes may damage structures, roadways, and other human infrastructure. Earthquakes can also trigger other hazards like tsunamis and landslides.

Where do earthquakes happen?

Earthquakes can happen anywhere different forces are applied on either side of a fault. Earthquakes are most common along plate boundaries. Severe earthquakes occur along transform boundaries and at convergent boundaries with subduction.

diagram of a transform plate tectonic boundary
This diagram shows how tectonic plates move along a transform boundary, sliding past one another.

Why do earthquakes happen?

We know that earthquakes usually happen at tectonic plate boundaries. But why? It all starts when forces, supplied by tectonic plate movement, are applied to a fault. A fault is a crack or fracture in the bedrock. First, the rocks on either side of the fault must experience different forces. But even when different forces are applied on either side of a fault, the friction between the rocks prevents movement. This causes strain to build.

When the strain becomes too great, it overcomes the friction, and the rocks move rapidly along the fault. This produces ground movement and shaking – what we experience during an earthquake. Think of it like slowly overstretching a rubber band – eventually it will break and rapidly snap back, releasing stored energy. Look at the example below, which shows how forces applied to different sides of faults create an earthquake.

These diagrams show how strain builds along a fault then is released during an earthquake.

How are earthquakes measured?

The ground movement during an earthquake is caused by seismic waves. Scientists can measure these waves by measuring the ground’s movement up and down or side to side. By measuring seismic waves at different locations, scientists can pinpoint the focus of an earthquake – that is, the exact spot within the ground where the seismic waves are coming from. The epicenter of an earthquake is directly above the focus, on the Earth’s surface.

In addition to finding the location of an earthquake’s focus and epicenter, scientists also measure and compare the size of earthquakes. Often, we rank earthquakes using a number called the magnitude. Lower magnitude earthquakes are common and usually cause minimal damage. Higher magnitude earthquakes are less common but may cause serious damage.

This image shows the epicenter and focus of an earthquake. Different forces applied to either side of a fault cause strain to build. When the strain becomes too great, rapid movement happens along the fault, which causes an earthquake.

How can we protect ourselves from earthquakes?

In areas at risk of severe earthquakes, people take steps to protect themselves. For example, engineers design buildings that are earthquake-resistant. During an earthquake, the ground under the building rapidly moves back and forth, which makes the building bend and sway. To withstand this, buildings must be made from strong, flexible materials that can bend without breaking or cracking. One good material is steel, but there are other options as well.

Individual people and families can also take measures to protect themselves from earthquakes. Know the earthquake risk in your area. If your area is at risk, make a family earthquake plan for what to do and where to go if an earthquake happens.

Continue Reading…

Continue reading about plate tectonics, Earth’s layers, volcanic activity, and more:

Study earthquakes with Wild Earth Lab!

There’s no need to scramble to put together the perfect earthquakes lesson  – I’ve already created it for you, and you’ll find it within my complete Plate Tectonics Unit! This set includes all the printable materials you need for studying this subject.

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Find your next topic, from Wild Earth Lab…

If you enjoyed this post, I know you will love trying my other science and nature units in your classroom too!

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References and Further Reading

  1. British Geological Survey (n.d.). What causes earthquakes? Available: https://www.bgs.ac.uk/discovering-geology/earth-hazards/earthquakes/what-causes-earthquakes/
  2. Michigan Tech (n.d.) Why do earthquakes happen? UPSeis. Available: https://www.mtu.edu/geo/community/seismology/learn/earthquake-cause/
  3. C.C. Plummer, D.H. Carlson, and L. Hammersley (2019). Physical Geology. McGraw-Hill Education. (Chapters 1, 4, 16, and 19)
  4. Thompson, A. (2023). How to Engineer Buildings That Withstand Earthquakes. Scientific American. Available: https://www.scientificamerican.com/article/how-to-engineer-buildings-that-withstand-earthquakes/

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A Guide to The Theory of Plate Tectonics

a classroom guide to the theory of plate tectonics
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Perhaps you are wondering: “What is the Theory of Plate Tectonics?” Get ready to find out! This post guides you through the theory of plate tectonics and how tectonic plates move. You will learn what tectonic plates are, why they move, and what it takes for a concept to become a scientific theory. The post ends with links to a few additional tools for teaching plate tectonics, including other helpful blog posts and other related resources for studying plate tectonics and similar topics.

For Teachers: If you’re an educator planning to teach plate tectonics, you know that engaging activities and thoughtfully crafted visuals are key to deepening understanding. That’s why I create Earth science units that are packed with hands-on activities and my watercolor artwork incorporated into diagrams. The information in this post comes from my comprehensive Plate Tectonics Unit, which includes handouts, worksheets, activities, and diagrams covering tectonic plate boundaries, Earth’s layers, volcanoes, and earthquakes. I think you and your students will love it (plus you’ll support my blog with your purchase! ❤️)

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What is a tectonic plate?

You may already know that the Earth is made of several compositional layers: crust, mantle, and core. You may wonder: “Why does the Earth have layers?” It all comes down to density. Density tells us about how heavy something is relative to its volume. You may have noticed that differences in density allow oil to float on top of water. The oil stays on top because it is less dense than the water. Just like oil on water, Earth’s inner materials are separated into layers based on their densities. The less dense surface “floats” on top of the denser, inner layers.

This “floating” surface, however, is not just one big piece. Earth’s lithosphere (surface; comprised of the crust and upper mantle) is cool, rigid, and brittle compared to the hotter, softer layers beneath it. The brittle lithosphere is broken into massive, irregularly shaped pieces, called tectonic plates. Picture the Earth as a hard-boiled egg with a cracked shell. Some of the tectonic plates are so large that they span entire continents. Others are smaller. Tectonic plates in the lithosphere sit atop a denser, soft part of the mantle called the asthenosphere.

a diagram showing the compositional and mechanical layers of the Earth

Why do plates move?

Heat is the force driving plate movement. The Earth is cool on the surface but hot deep inside. Deep within the Earth, material heats and expands, causing it to rise towards the surface. As material rises, it cools and contracts, causing it to sink again. This cycle of rising and sinking creates convection currents in the mantle. These currents move the overlying tectonic plates. Of course, all this movement is happening gradually over a very long time. It is hard to imagine rocks moving and flowing, because it happens so slowly that we cannot see it. Most tectonic plates only travel a few inches or less each year.

What is the theory of plate tectonics?

The theory of plate tectonics is a scientific theory central to the field of geology. This theory explains that the surface of the Earth is broken into large plates that are slowly moving. These plates slide past and over one another. Their motion gradually changes the appearance of Earth’s landmasses and oceans over time. Plate movement also causes earthquakes and volcanic eruptions along plate boundaries.

There are a few different plate boundary types. They are:

  • Convergent boundaries – plates moving together
  • Divergent boundaries – plates moving apart
  • Transform boundaries – plates sliding past one another

You can read more about these in my post on tectonic plate boundary types.

boundary type diagrams
These tectonic plate boundary diagrams come with my Plate Tectonics Unit.

What is a theory in science?

Conversationally, the word “theory” can mean a hunch or guess. But in science, theory has a different meaning. A scientific theory is an explanation of events in the natural world that has been widely and repeatedly tested. Theories are universally or nearly universally accepted among scientists. This is because theories are supported by lots of evidence, gathered using the scientific method.

If new evidence is found that does not fit with a theory, the theory can be modified or rejected. A theory provides a framework that ties together and explains many observations of the natural world. Theories not only explain what is happening, but also why or how it happens.

Classroom Activity: Can you think of any other theories from science? In small groups, assign students different theories from various scientific fields. Have each group look up the theory, then explain the theory to the class in a few sentences. (Suggestions: cell theory, theory of evolution by natural selection, big bang theory, climate change, plate tectonics)

More Tools for Teaching Plate Tectonics

If you want to continue learning more about plate tectonics, try one of these:

Study Plate Tectonics with Wild Earth Lab!

There’s no need to scramble to put together the perfect plate tectonics lessons– I’ve already created them for you and organized them into a complete Plate Tectonics Unit! This set includes all the printable materials you need for studying tectonic plates, the layers of the Earth, volcanoes, and earthquakes.

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Explore more lessons from Wild Earth Lab:

If you enjoyed this post, I know you will love trying my other printable science and nature units in your classroom too!

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Metamorphic Rocks: properties, formation, and subtypes!

a large foliated rock sample being examined by students
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Learning about rocks and the rock cycle in your classroom this year? You may already know that there are three main types of rocks: igneous, sedimentary, and metamorphic. In this post, we will take a closer look at metamorphic rocks. Get ready to explore the formation, subtypes, properties, and examples of metamorphic rocks!

For Teachers: If you’re an educator planning to teach rocks, great visuals and activities are key to deepening understanding! Try my my Rocks Unit – a complete set of all the printable worksheets, activity directions, and visuals you’ll need (plus you’ll support this blog with your purchase! ❤️)

How do metamorphic rocks form?

Metamorphic rocks form deep below the Earth’s surface. Metamorphic rocks form when other rocks experience lots of heat and pressure underground. The heat comes from the Earth’s interior and the pressure comes from the weight of overlying layers of rock and sediment.

Every metamorphic rock was once a different rock, called the parent rock, or protolith. The protolith can be sedimentary, igneous, or even a different metamorphic rock. For example, when the sedimentary rock sandstone is exposed to intense heat and pressure, it can become the metamorphic rock quartzite. This transformation, called metamorphism, forces the minerals in the parent rock to reorganize into a more compact structure, making metamorphic rocks quite sturdy and dense.

Metamorphism can only happen when the amount of heat and pressure are just right. If there is too little heat and pressure, metamorphism will not happen. If the heat and pressure grow too high, the rock will melt into magma instead.

Properties of Metamorphic Rocks

There are many different metamorphic rocks, and they do not all look the same. Shimmering schist, sturdy slate, and glimmering marble are all metamorphic! Their varied appearances are influenced by several properties including their mineral composition, grain (crystal) size, and foliation. Let’s learn some more about each of these properties…

Composition

As you now know, metamorphic rocks all share one important thing in common: they formed under heat and pressure. However, each rock has its own special blend of minerals. Metamorphic rocks are made of one or more minerals. If you can identify the mineral(s) in a rock, it will help you identify the rock.

Grain Size

Metamorphic rocks are made of crystals of minerals. Crystals come in different sizes. Rocks with large crystals can appear sparkly or shimmery, like schist or marble. But not all crystals are big. In fact, some rocks are made of crystals so tiny that you need a microscope to see them. Rocks made of microscopic crystals may appear more dull.

In general, bigger crystals form under higher heat and pressure. A rock with large, visible crystals formed under higher heat and pressure than a rock made of tiny crystals.

Foliation

Some (but not all) metamorphic rocks have foliation – which means banding or layering. Foliation presents in several different ways, depending on the conditions while the rock is formed and the mineral crystals in the rock. A foliated rock with large crystals formed under high heat and pressure. This rock may appear to have bands or stripes of different colored mineral crystals. An example of this is gneiss, which appears to have alternating bands of light and dark crystals. However, a foliated rock with microscopic crystals formed under lower heat and pressure. This rock may appear to be made of layers or plates, like slate.

diagram of igneous rock textures: phaneritic, aphanitic, porphyritic, bubbly, glassy, and pyroclastic

Metamorphic Subtypes

There are two types of metamorphic rocks: foliated and nonfoliated. With a little practice, you can learn to tell them apart. Let’s learn a little more about each.

Metamorphic Foliated

Metamorphic foliated rocks have bands or layers. Some, like gneiss, have alternating bands of light and dark crystals. Others, like phyllite and slate, look like they are made of sheets or layers. Foliation forms when a rock is being squeezed hardest in a particular direction rather than from all sides. This may happen when a rock is buried deep underground. The directed pressure forces the minerals to line up in the same direction, creating the bands or layers.

Metamorphic Nonfoliated

Metamorphic nonfoliated rocks form when the pressure comes from all sides or if the minerals do not line up. Consequently, nonfoliated rocks do not have bands or layers. Instead, nonfoliated rocks are usually a single solid color and made of interlocking mineral crystals. These crystals can be quite large or appear fine-grained. Some nonfoliated rocks, like marble, are prized for their strength and beauty, which makes them popular in construction and fine arts.

Teaching rocks? Check out my printable handouts with info on metamorphic, igneous, and sedimentary rocks!

Examples of metamorphic rocks

Here are some examples of common metamorphic rocks. If you’re studying rock identification or creating a rock collection, you’ll want to make sure to examine the following rocks:

Foliated Rocks

  • Gneiss
  • Schist
  • Phyllite
  • Slate

Nonfoliated Rocks

  • Marble
  • Quartzite
  • Hornfels

What’s Next?

For everyone: there’s more to learn about rocks! Take a closer look at igneous rocks or sedimentary rocks. Or, continue reading more about the rock cycle or the difference between rocks and minerals.

For educators: check out my posts on how to set up a rock ID lab activity, directions for a fun rock ID review bingo game, and a list of rock and mineral activity ideas that you can try in your classroom!

Study this topic with Wild Earth Lab!

I’ve already created an easy way for you to make teaching rocks & minerals in your classroom fun and engaging! This set includes all the printable materials you need for studying rocks and minerals, including diagrams, readings, activity directions, and worksheets!

Explore more lessons from Wild Earth Lab:

If you enjoyed this post, I know you will love trying my other printable science and nature units in your classroom too!

View All Units
Build-Your-Own Bundle & Save!

Are you interested in reading more posts like this? Subscribe or follow Wild Earth Lab using the links below!

References and Further Reading

  1. Earle, S. (2019). Physical Geology. BCcampus Open Education. (Chapters 2-7). Available: https://opentextbc.ca/physicalgeology2ed/
  2. Johnson, C., Affolter, M.D., Inkenbrandt, P., & Mosher, C. (2017). An Introduction to Geology. Salt Lake Community College. (Chapters 3-6). Available: https://opengeology.org/textbook/
  3. Jones, C. E. (n.d.). Igneous Textures. University of Pittsburg. Department of Geology and Planetary Science. Available: https://sites.pitt.edu/~cejones/GeoImages/2IgneousRocks/IgneousTextures.html
  4. Plummer C.C., Carlson D.H., & Hammersley L. (2019). Physical Geology. McGraw-Hill Education. (Chapters 1-7).

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Sedimentary Rocks: properties, formation, and subtypes!

students examining rock samples in a science classroom
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Are you ready to learn all about rocks and the rock cycle in your classroom this year? If so, it’s important to know all about the three main types of rocks: igneous, sedimentary, and metamorphic. In this post, we will take a closer look at sedimentary rocks. Get ready to learn all about the formation, subtypes, properties, and examples of sedimentary rocks!

For Teachers: If you’re an educator planning to teach rocks, great visuals and activities are key to deepening understanding! Try my sedimentary rock printables, also found within my complete Rocks Unit – a complete set of all the printable worksheets, activity directions, and visuals you’ll need (plus you’ll support this blog with your purchase! ❤️)

How do sedimentary rocks form?

Sedimentary rocks form at or near the Earth’s surface.  They form from deposits of sediments, minerals, and/or organic matter.

On the Earth, forces like water and shifting temperatures work endlessly to break rocks down. The tiny broken-down pieces of rocks are called sediments. Some of the minerals in rocks may also dissolve in water, the same way sugar dissolves in tea. We call the dissolved minerals solutes.

Sediments and solutes move and are deposited in new places through a process called erosion. As sediments build up, something special happens. Sediments compact together under their own weight or are cemented together by crystallizing minerals. This forms new rocks, known as sedimentary.

Properties of Sedimentary Rocks

There are many different sedimentary rocks, and they do not all look the same. Soft mudstones, rough sandstones, and even coal are all sedimentary! Their varied appearances are influenced by several properties including their mineral makeup and grain (sediment particle) size. Let’s learn more about some of the properties of sedimentary rocks…

Sedimentary Grain Sizes

You already know that many sedimentary rocks are made from compacted and cemented sediments. The size of those sediments determines the type of sedimentary rock. Mudstones are made from the tiniest clay particles that are so small you cannot see them. Sandstones are made from little grains of sand, which you can see with your naked eye if you look at them up close. Conglomerate and breccia are made from the largest sediments – like gravel and small pebbles.

diagram of igneous rock textures: phaneritic, aphanitic, porphyritic, bubbly, glassy, and pyroclastic

Geologists call the size of the particles in a rock the “grain size”. Grain size is important because it impacts the porosity and permeability of a rock. Very porous rocks like sandstone and conglomerate make good aquifers that store water underground. Do you know where your drinking water comes from? If you drink well water, then your drinking water comes from an aquifer!

Sedimentary Composition

Sedimentary rocks contain compacted and cemented grains, crystals of mineral precipitates, or sometimes organic materials. However, each rock has its own special blend of minerals.

Some sedimentary chemical rocks (those made from recrystallized solutes) contain carbonates. Carbonates are minerals that react with acid – just like how baking soda reacts with vinegar. Geology students find out if a rock contains carbonates by placing a drop of acid on the rock and watching for bubbling or fizzing. Rocks that fizz or bubble in a reaction with acid contain carbonates.

Other sedimentary rocks contain organic carbon and consequently burn. Geologists test for organic matter by attempting to combust a rock. The organic matter in the rock will burn in a combustion reaction – allowing the geologist to see how much of the rock was organic.

Sedimentary Subtypes

There are several subtypes of sedimentary: clastic, chemical, organic, and biochemical. They are formed from different materials. Let’s learn a little more about each.

Sedimentary Clastic Rocks

Sedimentary clastic rocks, such as sandstone and siltstone, form from tiny solid particles of rock called sediments. Sediments form through a process called weathering, in which rocks break down over time into smaller pieces. These pieces move around thanks to forces like flowing water, wind, and gravity, eventually coming together to form new rocks.

But how do loose sediments become a solid rock? Two processes, compaction and cementation, are responsible. Compaction happens when sediments are buried and pressed into a rock by the weight above. Cementation happens when water evaporates, leaving behind minerals that act like cement, holding the sediments together. Clastic rocks vary in their grain sizes, from microscopic particles in mudstone to large gravel pieces in breccia and conglomerates.

Sedimentary Chemical Rocks

Have you ever stirred sugar into water until it disappears?  Although you cannot see the sugar, it is still there, dissolved in the water. Like sugar, many minerals dissolve in water too! Most liquid water on Earth contains dissolved minerals.

Now perhaps you are wondering: how does water make rocks? Imagine an ancient ocean, with water rich in dissolved minerals. As time passes, the ocean begins to shrink, eventually drying up completely. When the water evaporates, the minerals from the water recrystallize to form sedimentary chemical rocks. This process, called precipitation, is the opposite of dissolving. Sedimentary chemical rocks are crystalline but often look fine-grained. Some are made of carbonate and react strongly to acid. Rock salt and limestone are two examples of sedimentary chemical rocks.

Sedimentary Organic Biochemical Rocks

Sedimentary organic and biochemical rocks are similar to sedimentary clastic rocks. However, they aren’t composed of sediments but rather form from buried plant and animal matter. Through compaction and cementation, the matter eventually becomes rock. Examples include coal, formed from compressed plant matter, and coquina, made of compacted and cemented shell fragments. These rocks can tell us fascinating stories about life on Earth in prehistoric times!

Examples of sedimentary rocks

Here are some examples of common sedimentary rocks. If you’re studying rock identification or creating a rock collection, you’ll want to make sure to examine the following rocks:

Clastic Rocks

  • Mudstone
  • Siltstone
  • Sandstone
  • Conglomerate
  • Breccia

Chemical Rocks

  • Limestone
  • Rock salt
  • Chert
  • Ironstone

Biochemical and Organic Rocks

  • Fossiliferous Limestone
  • Coquina
  • Diatomite
  • Anthracite
  • Coal

What’s Next?

For everyone: there’s more to learn about rocks! Take a closer look at igneous rocks. Or, continue reading more about the rock cycle or the difference between rocks and minerals.

For educators: check out my posts on how to set up a rock ID lab activity, directions for a fun rock ID review game, and a list of rock and mineral activity ideas that you can try in your classroom!

Study this topic with Wild Earth Lab!

I’ve already created an easy way for you to make teaching rocks & minerals in your classroom fun and engaging! This set includes all the printable materials you need for studying rocks and minerals, including diagrams, readings, activity directions, and worksheets!

Explore more lessons from Wild Earth Lab:

If you enjoyed this post, I know you will love trying my other printable science and nature units in your classroom too!

View All Units
Build-Your-Own Bundle & Save!

Are you interested in reading more posts like this? Subscribe or follow Wild Earth Lab using the links below!

References and Further Reading

  1. Earle, S. (2019). Physical Geology. BCcampus Open Education. (Chapters 2-7). Available: https://opentextbc.ca/physicalgeology2ed/
  2. Johnson, C., Affolter, M.D., Inkenbrandt, P., & Mosher, C. (2017). An Introduction to Geology. Salt Lake Community College. (Chapters 3-6). Available: https://opengeology.org/textbook/
  3. Jones, C. E. (n.d.). Igneous Textures. University of Pittsburg. Department of Geology and Planetary Science. Available: https://sites.pitt.edu/~cejones/GeoImages/2IgneousRocks/IgneousTextures.html
  4. Plummer C.C., Carlson D.H., & Hammersley L. (2019). Physical Geology. McGraw-Hill Education. (Chapters 1-7).

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Igneous Rocks: properties, formation, and subtypes!

igneous rocks - texture diagram
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Are you studying rocks and the rock cycle in your classroom this year? If you’re ready to take a deep dive into all things rocks, it’s important to know all about the three main types of rocks: igneous, sedimentary, and metamorphic. In this post, we will take a closer look at igneous rocks. Get ready to learn all about the formation, subtypes, properties, and examples of igneous rocks!

For Teachers: If you’re an educator planning to teach rocks, great learning resources are key to deepening understanding! I think you and your students will love my complete Rocks Unit – a set of all the printable worksheets, activity directions, and visuals you’ll need (plus you’ll support my blog with your purchase! ❤️)

How do igneous rocks form?

All igneous rocks form from molten rock. When molten rock is underground, we call it magma. Molten rock is only called lava when it’s on Earth’s surface. The intense pressure and heat deep underground keep magma in the molten (liquid) form. However, when the heat and pressure lessen, the molten rock solidifies, forming crystals. This can happen very slowly while the rock is still underground. If the molten rock reaches the Earth’s surface, it cools much more rapidly. This is because the surface of the Earth is very cool compared to the Earth’s insides.

Properties of Igneous Rocks

There are many different igneous rocks, and they do not all look the same. Bubbly pumice, smooth obsidian, and sparkly granite are all igneous rocks! Their varied appearances are influenced by their mineral makeup and the specific conditions during their formation. Igneous rocks come in a wide variety of different textures and compositions. Let’s learn more about both of these properties…

Igneous Textures

As molten rock cools, it forms crystals. The size of these crystals depends on how quickly the rock cools. Slow cooling provides time for big, interlocking crystals to form. Rapid cooling makes tiny, fine-grained crystals. We use special terms to describe these different textures: phaneritic (big crystals), aphanitic (tiny crystals), and porphyritic (a mixture of both).  But that’s not all! Some lava rocks, like pumice, have a bubbly texture filled with tiny holes. Others, like obsidian, are smooth and look glassy. There are even rocks made of many pieces of volcanic debris all stuck together, giving them what is known as a pyroclastic texture.

diagram of igneous rock textures: phaneritic, aphanitic, porphyritic, bubbly, glassy, and pyroclastic

Igneous Compositions

Igneous rocks also come in different colors, which can tell us a lot about the minerals inside them – i.e., their mineral compositions. Light-colored minerals rich in silicon and oxygen are called felsic minerals. Rocks with lots of felsic minerals, like granite and rhyolite, are usually light and warm in color. On the other hand, dark-colored minerals rich in iron or magnesium are called mafic minerals. Rocks with lots of mafic minerals, like gabbro and basalt, are mostly dark gray, black, or green.

Subtypes

There are two main subtypes of igneous rocks: intrusive and extrusive. The main difference between them is where they form. Intrusive rocks form within the Earth while extrusive rocks form on the Earth’s surface.

Igneous Intrusive Rocks

More specifically, an igneous intrusive rock starts as magma, which is what we call molten rock located underground. The magma is insulated deep within the Earth, so it cools very slowly. The slow cooling allows plenty of time for large interlocking crystals to form. Granite, diorite, and gabbro are examples of igneous intrusive rocks.

Igneous Extrusive Rocks

In contrast, igneous extrusive rocks form when hot lava cools on the Earth’s surface such as when a volcano erupts. Lava cools very quickly on the surface, so there is not enough time for big crystals to form. If you are trying to decide if an igneous rock is intrusive or extrusive, texture is your biggest clue! While intrusive rocks are always made of large interlocking crystals, extrusive rocks come in a variety of other textures: fine-grained, glassy, bubbly, and more! Basalt, rhyolite, and pumice are igneous extrusive rocks.

Examples of igneous rocks

Here are some examples of common igneous rocks. If you’re studying rock identification or creating a rock collection, you’ll want to make sure to examine the following rocks:

Aphanitic or Porphyritic Rocks

  • Granite
  • Diorite
  • Gabbro
  • Peridotite

Phaneritic Rocks

  • Rhyolite
  • Andesite
  • Basalt

Vesicular Rocks

  • Pumice
  • Basalt
  • Scoria

Others (pyroclastic & glassy)

  • Tuff
  • Volcanic Breccia
  • Obsidian

What’s Next?

For everyone: there’s more to learn about rocks! Continue reading more about the rock cycle or the difference between rocks and minerals.

For educators: check out my posts on how to set up a rock ID lab activity, directions for a fun rock ID review game, and a list of rock and mineral activity ideas that you can try in your classroom!

Study this topic with Wild Earth Lab!

There’s no need to scramble to put together the perfect rocks lesson  – I’ve already created it for you! This set includes all the printable materials you need for studying rocks and minerals.

Explore more lessons from Wild Earth Lab:

If you enjoyed this post, I know you will love trying my other printable science and nature units in your classroom too!

View All Units
Build-Your-Own Bundle & Save!

Are you interested in reading more posts like this? Subscribe or follow Wild Earth Lab using the links below!

References and Further Reading

  1. Earle, S. (2019). Physical Geology. BCcampus Open Education. (Chapters 2-7). Available: https://opentextbc.ca/physicalgeology2ed/
  2. Johnson, C., Affolter, M.D., Inkenbrandt, P., & Mosher, C. (2017). An Introduction to Geology. Salt Lake Community College. (Chapters 3-6). Available: https://opengeology.org/textbook/
  3. Jones, C. E. (n.d.). Igneous Textures. University of Pittsburg. Department of Geology and Planetary Science. Available: https://sites.pitt.edu/~cejones/GeoImages/2IgneousRocks/IgneousTextures.html
  4. Plummer C.C., Carlson D.H., & Hammersley L. (2019). Physical Geology. McGraw-Hill Education. (Chapters 1-7).

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How to Play Rock ID Bingo: directions for a review game!

rock id bingo cards
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Rock identification can be a challenging but fun subject to teach in any science classroom. If you’ve taught your students the basics of rock ID, but need a fun review game to end your unit or prepare for a test, I’ve got you covered! In this post, I’ll share the materials and directions for playing rock ID bingo in your classroom!

If you’re teaching rock identification, you are probably studying minerals too! If you’d like to review mineral ID as well, you can head over to my separate post about how to play mineral ID bingo!

Before we dive in: If you’re an educator planning to try this game with your students, you can save yourself the time of making your own bingo cards and calling cards. My printable rock ID bingo card set is available on TpT and Etsy. The set includes 25 unique bingo cards with illustrations of each rock, plus calling cards with each rock’s key traits and other hints (plus you’ll support this blog with your purchase! ❤️)

Prior Knowledge Required

To do this activity, your students must know the difference between rocks and minerals. They should have already practiced some rock ID and be familiar with common rocks such as:

  • Granite
  • Basalt
  • Pumice
  • Marble
  • Gneiss
  • Slate
  • Sandstone
  • Limestone
a box of rock samples

Furthermore, your class should be familiar with the following rock-related concepts:

You can brush up on rock ID by working through a rock identification lab activity with your class by following these directions. Or, read my list of fun rock & mineral activity ideas for other geology projects and lessons for your classroom.

Finally, you can get my most comprehensive rock and mineral teaching materials in the Rocks and Minerals Unit. It’s my complete set of printable materials for teaching rocks and minerals – with worksheets, activity directions, tons of diagrams, and much more. I know you will love it!

Materials

To play rock ID bingo, you will need the following materials

  • 25 unique bingo cards featuring different rocks (download & print mine here, featuring common rocks, or create your own with your rocks of choice)
  • Calling cards – a list of each rock’s traits (hints) on small pieces of paper or index cards (also included in my printable bingo set!)
  • A hat or bucket
  • Bingo chips or small items (pennies, candies) to place over the squares on the bingo cards

How to Play

Follow these steps to play rock ID bingo with your students:

  1. Each student gets one unique bingo card.
  2. Cut apart the calling cards with each rock’s properties/hints. Place your calling cards into a hat or bucket.
  3. Pull one calling card at a time and read it out loud to the class, sharing the hints and properties of the rock without revealing the name of the rock.
  4. Students should find the corresponding rock on their bingo cards and mark or cover it.
  5. The first student to get four rocks in a row gets “bingo” (across, diagonal, or vertical).
  6. Check the student’s card to ensure all rocks were identified correctly.

Helpful Hints

When reading out clues for a rock, start with the more obscure hints, and then progress to the more obvious clues.

Products Mentioned in this Post:

There’s no need to scramble to put together the perfect printable materials for this activity  – I’ve already created it for you! This bingo set includes all the printable materials you need for playing rock ID bingo.

For more rocks and minerals learning fun, try my Rocks & Minerals Unit – a complete set of printable classroom materials for teaching this subject:

Studying mineral ID too? Check out my mineral ID bingo review game as well:

Explore more lessons from Wild Earth Lab:

If you enjoyed this post, I know you will love trying my other printable science and nature units in your classroom too!

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Geology Review Game Idea: mineral ID bingo

mineral ID bingo cards
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Are you teaching rocks & minerals in your science classroom? If you’ve taught your students the basics of mineral ID, but need a fun review game to end your unit, look no further than mineral ID bingo. In this post, I’ll go over how to play mineral ID bingo in your classroom and the materials you will need to play!

Before we dive in: If you’re an educator planning to try this game with your students, you can save yourself the time of making your own bingo cards and calling cards. My printable mineral ID bingo card set is available on TpT and Etsy. The set includes 25 unique bingo cards with illustrations of each mineral, plus calling cards with a list of each mineral’s properties (plus you’ll support this blog with your purchase! ❤️)

Prior Knowledge Required

To do this activity, your students must know the difference between rocks and minerals. They should have already practiced some mineral ID and be familiar with common minerals such as:

  • Biotite
  • Calcite
  • Feldspar
  • Galena
  • Halite
  • Muscovite
  • Pyrite
  • Quartz

Furthermore, your class should be familiar with the physical properties of minerals, including:

You can brush up on mineral ID and mineral physical properties by reading my post about mineral physical properties. You could also try a mineral ID lab with your class, by following these directions or reading my list of fun rock & mineral activity ideas for the classroom.

Finally, you can get my most comprehensive rock and mineral teaching materials in the Rocks and Minerals Unit. It’s my complete set of printable materials for teaching rocks and minerals – with worksheets, activity directions, diagrams, and much more. I know you will love it!

an eye dropper held above some mineral samples
Example of a Mineral ID lab activity

Materials

To play mineral ID bingo, you will need the following materials

  • 25 unique bingo cards featuring different minerals (download & print mine here, featuring common minerals, or create your own with your minerals of choice)
  • Calling cards – a list of each mineral’s physical properties (hints) on small pieces of paper or index cards (also included in my printable bingo set!)
  • A hat or bucket
  • Bingo chips or small items (pennies, candies) to place over the squares on the bingo cards

How to Play

Follow these steps to play mineral ID bingo with your students:

  1. Each student gets one unique bingo card.
  2. Cut apart the calling cards with each mineral’s physical properties. Place your calling cards into a hat or bucket.
  3. Pull one calling card at a time and read it out loud to the class, sharing the physical properties of the mineral without revealing the name of the mineral.
  4. Students should find the corresponding mineral on their bingo cards and mark or cover it.
  5. The first student to get four minerals in a row gets “bingo” (across, diagonal, or vertical).
  6. Check the student’s card to ensure all minerals were identified correctly.

Helpful Hints

When reading out clues for a mineral, start with the more obscure hints, and then progress to the more obvious clues.

Products Mentioned in this Post:

There’s no need to scramble to put together the perfect printable materials for this activity  – I’ve already created it for you! This bingo set includes all the printable materials you need for playing mineral ID bingo.

For more rocks and minerals learning fun, try my Rocks & Minerals Unit – a complete set of printable classroom materials for teaching this subject:

Studying Rock ID too? Check out my rock ID bingo review game as well:

Explore more lessons from Wild Earth Lab:

If you enjoyed this post, I know you will love trying my other printable science and nature units in your classroom too!

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Teaching Landforms: sorting and compare & contrast activities

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Teaching landforms in your classroom? If you’re searching for a quick and easy way to help students learn about landforms—without needing lots of extra supplies—you’ve come to the right place! This post shares simple sorting and compare/contrast activities perfect for introducing landforms. All you’ll need are some landform flashcards or pictures, making this activity both fun and hassle-free!

Materials

All you need for this simple learning activity is some good landform flashcards or pictures. I recommend downloading and printing my landform three-part cards. Optionally, you can also purchase my water features three-part cards. You’ll receive high-quality illustrations of each landform on printable flashcards, plus you’ll support my blog with your purchase!

landforms flashcards

Or, if you’re looking for EVEN MORE landforms materials for your lessons, I recommend checking out my complete Landforms Unit. It includes the landforms flashcards, a printable version of the directions in this blog post, and additional activities and printable materials.

Step 1: Get to know the common landforms

Using your landform flashcards, work through the following steps with your students to introduce the common landforms.

  • Look through the whole-card flashcards together.
  • Read the definitions on the information cards and learn about how each common landform is formed.
  • Practice matching landform pictures to landform names with the picture-only and word-only flashcards.
  • Can you spot any of these landforms on the coastal and desert landscape posters?

Landform Sorting Activities

Arrange the flashcards into different groups:

  • Landforms that are surrounded by water and landforms that are not surrounded by water.
  • Landforms made of loose sand or soil and landforms made of solid rocks.
  • Landforms that stick up out of the earth and landforms that go down into the earth.

Which landforms…

Which landforms…

  • Are flat on top?
  • Are pointy?
  • Are steep?
  • Are gently sloping?
  • Are hollow inside?
  • Can be found in your local area?

Compare and Contrast

Look for some similarities and differences between each pair of landforms:

  • Island and peninsula
  • Peninsula and isthmus
  • Mountain and volcano
  • Mountain and hill
  • Hill and sand dune
  • Valley and canyon
  • Cave and volcano
  • Mesa and mountain
  • Cliff and canyon

How did it form? (advanced!)

  Find the cards for the landforms that are formed by:

  • Erosion
  • Deposition
  • Volcanic activity
  • Plate tectonics

(Hint: some landforms can form in more than one way and may fit into more than one category)

What’s Next?

Continue reading about the different types of landforms (complete with examples of each type!) You can also read my post about water features.

Study this topic with Wild Earth Lab!

There’s no need to scramble to put together the perfect landforms lesson  – I’ve already created it for you! This set includes all the printable materials you need for studying landforms in your classroom or homeschool!

Explore more lessons from Wild Earth Lab:

If you enjoyed this post, I know you will love trying my other printable science and nature units in your classroom too!

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Rock ID Lab: directions and materials list for a classroom geology activity

a box of rock samples

In this activity, students will become familiar with rocks’ physical properties and the basics of rock identification. Students will sort rocks into groups based on their observations and learn about the physical properties of rocks. At the end of the rock ID lab, students can try identifying rocks by type, subtype, and name.

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No prior rock ID experience is needed for students to complete this lab activity. Part A especially is a great way for beginners to explore the physical properties of rocks! However, before beginning parts B and C of this activity, students should already be familiar with the rock cycle and the three main types of rocks (igneous, sedimentary, and metamorphic!) and their sub-types.

Before starting the lab, students should also know the difference between rocks and minerals. Often, it makes sense to do a mineral lab before diving into a rocks ID lab. You can find my mineral lab online write up (free) or the printable directions (for purchase).

Please Note: I’ve made the directions for this rock ID lab activity available for free here in this post. However, if you want printable directions, worksheets, flashcards, readings, and teaching posters for a rock ID lab, you can purchase them in my shop. The printable rock ID flashcards are included but also sold individually. Or, you can find all these materials plus more in my complete Rocks and Minerals Unit.

Printable Rock ID Materials
Printable Rock Flashcards Only
Full Rocks & Minerals Unit

Materials

This activity requires one of each item per lab group unless stated otherwise.

  • 10+ rock  samples labeled with numbers 1-10+
    • Recommended: granite, gabbro, rhyolite, basalt, limestone, conglomerate, mudstone, gneiss, slate, and marble
    • You can complete this lab with a different rock sample set, but it is ideal to have a mixture of common igneous, sedimentary, and metamorphic rocks.
  • Hand lens or microscope
  • Juice of a lemon
  • Eye dropper
  • Student worksheets (1 set per student)
  • Teaching posters
  • Rock cards
Save preparation time AND support my blog: purchase all the printable materials you need to complete a rock ID lab in my shop!

Modifications (optional)

  • To make this rock ID lab simpler, do parts B and C all together as a class.
  • As an alternative to parts B and C, you could tell students which rocks are igneous, sedimentary, and metamorphic and then ask students to find some similarities between the rocks within each group.
  • To simplify part C, tell your students which 10 rock samples they have, but do not tell them which is which. This allows students to use the process of elimination to identify the most difficult samples.

Safety Notes

  • Read and comply with any warnings on the packaging and safety information sheets of rock samples and test kit tools used to complete this lab.
  • Adult supervision is required at all times while completing this lab.

Directions

Part A: Examine the Rocks

  1. Allow the students to familiarize themselves with the rock samples by picking them up, looking at them, etc…
  2. Ask the students to take note of which rock samples…
    • Are light colored?
    • Are dark colored?
    • Have several different colors?
    • Are one solid color?
    • Are made of crystals? (use hand-lens or microscope)
    • Are made of sediment particles stuck together? (use hand-lens or microscope)
    • Are fine-grained?
    • Sparkle?
    • Are dull?
    • Are soft or break or crumble easily?
    • Are very solid and don’t break or crumble?
    • Have stripes or layers? (foliation)
    • React to an acid (lemon juice)?
      • Note for acid reactions: rocks with a very high calcium carbonate content (e.g., marble, limestone, and coquina) should react with a drop or two of acidic lemon juice. They will bubble and fizz. Rocks with a lower calcium carbonate content (e.g., some mudstones) may bubble and fizz slightly.
Need worksheets and handouts? Purchase my set of printable materials that complement this activity!

Part B: Rock Types & Sub-Types

  1. As a class, review or research the properties of igneous, sedimentary, and metamorphic rocks and their sub-types. Create a list of the properties (texture, composition, foliation, etc…) you might see in each of these rock types and subtypes:
    • Igneous:
      • Extrusive
      • Intrusive
    • Sedimentary:
      • Chemical
      • Clastic
      • Biochemical and organic
    • Metamorphic:
      • Foliated
      • Nonfoliated
  2. As you create your lists, introduce/review the following concepts: mafic vs felsic, igneous textures, grain sizes, and foliation. For this step, the teaching posters found in my product will be a helpful visual aid.
  3. Students should write detailed descriptions of each rock sample, noting the following physical properties:
    • Texture (use a microscope or hand lens)
    • Composition
    • Luster
    • Color
    • Foliation (use hand lens if needed)
    • Acid reaction (strong reaction, weak reaction, no reaction)
    • Other properties
  4. See if your students can correctly identify the type or subtype of any of the rock samples.
    • Start with rocks that can be most easily identified. For example, a rock with clear foliation can quickly be identified as a metamorphic foliated rock. A rock that is made of sediment particles cemented together can be quickly identified as a sedimentary clastic rock.
    • It is OK if there are some rocks that your students are unsure about. Discuss why they are unsure and if there are any types/sub-types they can rule out. It may not be possible to identify certain rocks in a classroom setting.
  5. After this part of the lab is complete, reveal which rocks were sedimentary, igneous, and metamorphic. You may also lead a discussion on how the physical properties of rocks relate to how they formed. E.g., large crystals form deep underground, foliation forms under directional pressure, etc…
Teaching posters for this Rock ID activity(available for purchase)

Part C: Rock ID

  1. Pass out the rock information flashcards or a different rock ID guide of your choosing.
    • For an added challenge: encourage students to only look at the front (info/text-only) side of the flashcards while making their IDs. The backs of the flashcards include pictures and names of the rocks.
  2. The students should read the properties listed on each flashcard.
  3. Students can compare the rock properties on the flashcards to their written descriptions of each sample.
  4. Students should do their best to match each rock sample to its correct identity.
  5. Rock ID is challenging: assist students if they become stuck.
  6. End the lab by revealing the correct identity of each sample.
My Rock ID cards make identifying common rocks a breeze!

Study Rocks and Minerals with Wild Earth Lab!

Save time by purchasing all the printable materials you need for a rock ID lab! This set includes all the worksheets, teaching posters, flashcards, and handouts you need for completing this rock ID activity:

OR: you can also find all the above materials plus more in my full Rocks and Minerals Unit:

Explore more lessons from Wild Earth Lab:

If you enjoyed this post, I know you will love trying my other science and nature units in your classroom too!

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7 Rocks & Minerals Activity Ideas: learning activities to try in your classroom!

child's hand holding a model of a fossil and paintbrush

Wild Earth Lab is supported by readers like you. This post includes links to my own products and affiliate products. If you purchase through links on my site, I may earn a small commission at no additional cost to you.

Rocks and minerals are an important topic in the field of geology. Learning about rocks and minerals can be so fun for both kids and adults. Here are 7 hands-on rocks and minerals activity ideas to try out in your classroom or homeschool.

A note for teachers: if you’re planning to teach rocks & minerals, great learning resources are key to deepening understanding. That’s why I created my complete Rocks & Minerals Unit. It’s packed with hands-on lab activities, thoughtfully crafted visuals, and all the worksheets and handouts you need to study rocks and minerals. Plus, every purchase helps support this blog! ❤️

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1. Rock Cycle Model

Try making a model of the rock cycle. This is a popular rock and mineral activity for the classroom! There are many ways to do this – with chocolate, marshmallows, Starburst candies, crayons – the list goes on.

The basic concept is this:

  • Sedimentary Rocks: big solid chunks lightly compacted until they stick together. This can be done by cutting up the material into pieces and then squeezing the pieces together in your hands until they stick together.
  • Metamorphic Rocks: warped under heat and/or pressure, but not enough to fully melt. This is done by briefly warming your material to a moderate temperature in an oven and then applying pressure.
  • Igneous Rocks: fully melted, the re-solidified material. This can be done by fully melting your material in an oven and then allowing it to cool at room temperature.
melted chocolate in white bowl
You can use chocolate to model the rock cycle! Melted chocolate symbolizes molten rock! Photo by Monstera Production on Pexels.com

This activity is great for teaching the basics of the rock cycle before continuing on with the other rocks and minerals activity ideas.

2. Mineral Lab

Minerals are the building blocks of rocks. Geologists can examine minerals for their physical properties and then identify them. A minerals lab is super fun because it involves testing minerals for magnetism, acid reaction, and other unique physical properties! To test for these properties, you will need to make or buy a mineral test kit, such as this test kit (external link).

With a little practice, you and your students can identify common minerals too. Read my separate post here about how to set up your own minerals lab in your classroom. You can also download my Minerals Mini Study, which includes all of the worksheets, handouts, and directions that you’ll need for an awesome mineral lab in your classroom!

The activities in the blog post come from my Minerals Mini Study. Download the mini study with worksheets, handouts, directions, and more.

3. Guided Geology Hike

Are there any national parks or state parks in your area? Some have rangers who will put on guided nature hikes covering many topics, including local geology.

If not, you could also reach out to a local geology expert to join your class or homeschool group on a hike to learn about geology. When I was a graduate student, a homeschool group reached out to me to lead a geology hike like this. We hiked a short way through a canyon and talked about how plate tectonics and flowing water helped shape the area.

4. Make Rock Candy

This is a tasty way to learn about mineral precipitates, which you may know form some of our sedimentary rocks, such as limestone. This activity takes several days, during which you will watch crystals form! You can follow a rock candy recipe, such as this recipe (external link).

5. Rock Identification

Rock ID can be challenging, but it is so rewarding to be able to identify common rocks in your area. Learn about foliation, grain size, rock compositions, textures, and more! If you are looking for a good place to get started with Rock ID, I think you’ll love my Rocks Mini Study. It includes all the printable handouts, worksheets, and directions you will need for an awesome Rocks Lab! Another fun activity to try is Rock ID Bingo – more on this below!

If you are looking to learn how to identify rocks, try out my Rocks Mini Study. It includes all the handouts, worksheets, and directions for a rock ID activity!

6. Play Rock or Mineral Bingo

These are great review games for practicing rock and mineral identification. Each student gets a bingo card with different rocks or minerals. The teacher then reads out the properties of a mystery rock or mineral. The students must figure out which rock or mineral it is, then mark it on the bingo card!

I’ve created these mineral bingo and rock bingo sets (complete with calling cards!) to help you play this game in your classroom:

7. DIY Fossils

Unlike living things, which come and go, rocks stick around for incredibly long periods. This allows rocks to act as time capsules, preserving clues about our planet’s past – fossils! Learn about how fossils form by creating your own fossils (external link).

Bonus: see real fossils up close for inspiration! Look for a geology museum in your area to see collections of amazing and rare gems, minerals, rocks, fossils, and much more! You can also look for gem and mineral show events in your area (external link).

paper dyeing with brown dried leaves
Photo by Paul Seling on Pexels.com
white dinosaur skeleton displayed on a wooden table in a museum
Photo by Ansbert Bignon on Pexels.com

Study Rocks and Minerals with Wild Earth Lab

Many of the rock and mineral activity ideas from this post are found in or go great with my complete Rocks and Minerals Unit! It is a complete set of printable materials including worksheets, handouts, classroom posters, lab activities, and much more!

Explore curriculum from Wild Earth Lab:

If you enjoyed the rocks and minerals activity ideas in this post, I know you will love using my environmental science materials in your classroom!

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