Natural Resources

In this unit, students use what they know about the relationship between energy and matter to investigate how energy powers the cycling of Earth materials. In this lesson, they analyze the phenomena of processes that form fossil fuels, which determine how these natural resources are distributed around the planet. This page highlights all the parts of this lesson.

Science Background for Teachers:

The science background section gives teachers more in-depth information on the phenomena students explore in this unit. Below is an excerpt from the science background on natural resources.

Fossils and Fuel

Scientists can read the size, shape, and arrangement of sedimentary particles to get an idea of the environmental conditions on Earth over time. The type of sediment and fossils found in sedimentary rock may reveal ancient oceans, glaciers, and swamps that existed and disappeared over time. Sedimentary rock can also tell geologists something very valuable: that crude oil or natural gas may be present.

Long before the dinosaurs roamed, more than 300 million years ago, oceans covered most of Earth’s surface. The oceans teemed with tiny plants and animals called plankton. After these organisms died, they sank to the bottom of the ocean. Over time, sand and mud covered their remains.

As the once-living remains decomposed, they formed organic material that mixed with the sediment. Organic material is anything that is living or was once living, such as fallen leaves or animal remains. Anything that is not living and never was living is inorganic. Water and rocks are both inorganic. As new sedimentary layers were deposited, the layers put tremendous pressure on the sediment and organic matter, while Earth’s interior provided heat.

The heat and pressure turned the organic material into coal, crude oil, and natural gas. This is why coal, oil, and natural gas are called fossil fuels—they are nonrenewable energy sources that formed millions of years ago from plant and animal matter.

Chemical Reactions

The chemical reactions that transform dead organic matter into new substances with different properties require energy. That energy comes from deep within Earth’s interior. Just like matter, energy is never created or destroyed. This means that there is the same amount of energy today as there was during the time of the dinosaurs, but energy is always on the move, transforming from one form to another.

Remember that all chemical reactions require energy because it takes energy to break the chemical bonds holding atoms and molecules together, and it takes energy to form new bonds. In exothermic reactions, more energy is needed to break the bonds of the reactants than is needed to form the new bonds of the products. As a result, energy is released into the environment. In endothermic reactions, more energy is needed to form the bonds of the products than is needed to break the bonds of the reactants. That is why endothermic reactions absorb energy from their surroundings, becoming cooler.

Photosynthesis is an example of an endothermic reaction that is fundamental to all life. During photosynthesis, plants convert energy from the sun into a usable form of energy. The absorbed energy allows an endothermic reaction involving water and carbon dioxide to take place. Plants and animals store that energy, and it remains stored for millions of years as the organic remains turn into fossil fuels.

That stored energy is released in an exothermic reaction when the fossil fuels are burned. Exothermic reactions release thermal energy, making the surrounding temperature warmer. Exothermic chemical reactions that burn fossil fuels are some of the primary sources of energy in the United States.

Looking for Oil

Oil companies spend vast amounts of time, effort, and money searching for fossil fuels. Once geologists have a good sense of how fossil fuels are formed, they then look for clues in Earth’s geology to try to figure out where fossil fuels might be found. It’s not easy, because fossil fuels rarely stay where they are formed. Because Earth is a dynamic planet, once oil and gas are formed within rocks, they continue to move around the planet, in ways both big and small.

Let’s start with the small movements. Oil and gas form into a type of sedimentary rock called source rock—rock from which hydrocarbons are formed. Source rocks have organic material from the once-living organisms, as well as inorganic sediment.

Over time, crude oil flowed from the source rock and began to accumulate in a reservoir rock. Reservoir rocks hold oil and gas like a sponge. This is because they tend to have a lower density—the mass of a substance in a given area. They are also permeable and porous. Porosity refers to the number of spaces between particles in a substance. Porous rocks have tiny spaces, called pores, that allow substances such as oil to collect. Permeability refers to the ease with which substances move through a material.

Oil and gas move through the permeable reservoir rock. Some of it will reach Earth’s surface and seep out. More often, however, it will reach a kind of impermeable rock called cap rock. The cap rock holds the oil in place. Over many thousands or millions of years, the oil slowly builds up, forming a reservoir. These reservoirs are called oil and gas traps.

The tectonic plates can also cause entire reservoirs to move over millions of years. These complex motions make oil and gas reservoirs very difficult to find.

Supports Grade 8

Science Lesson: Exploring Natural Resources

Once students understand the processes that drive the rock cycle, they discuss how those same processes cause fossil fuels to form. Students use maps to evaluate the science phenomena of the distribution of oil and natural gas reserves in the U.S. and then analyze the physical properties of sedimentary rock samples to determine how oil and natural gas can be stored and contained within Earth.

Science Big Ideas

  • The processes that cause sedimentary rock to form are the same that are responsible for the formation of fossil fuels—nonrenewable energy sources that formed millions of years ago from plant and animal matter. Oil and natural gas are two kinds of fossil fuels.
  • Because of how fossil fuels are formed, there are patterns in where fossil fuels are found on Earth.

Sample Unit CTA-2
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Science Essential Questions

  • How are the processes that form oil and natural gas similar to the processes that form sedimentary rock?
  • Why are fossil fuels organic?
  • Why are oil and gas deposits usually found in areas that used to be ocean or where there is sedimentary rock?
  • What properties are needed for sedimentary rock to hold oil and gas?
  • Why is it important for oil and gas to be able to move through rock?

Common Science Misconceptions

Misconception: Geological processes happen in human time frames, and any change will happen within a person’s lifetime. 

Fact: Many of the changes to Earth’s surface occur over thousands or millions of years. Other changes can be very rapid.

Science Vocabulary

Fossil Fuel : a nonrenewable energy source that formed millions of years ago from plant and animal matter

Hydrocarbon : any chemical compound that consists only of the elements carbon (C) and hydrogen (H)

Inorganic : anything that is not living and never was living (e.g., water and rocks)

Organic : anything that is living or was once living (e.g., fallen leaves and animal remains)

Permeability : the ease with which substances move through a material; a property of matter

Porosity : having tiny spaces, called pores, that allow substances—such as oil or water—to pass through; a property of matter

Nonrenewable Resource : a resource that cannot be replenished in a short period of time

Lexile(R) Certified Non-Fiction Science Reading (Excerpt)

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A Geological Treasure Hunt

Shar Anderson spends her days using computer models and gathering data about the properties of rocks in particular locations. She sees her job as a treasure hunter, looking for clues on Earth’s surface and underground. Anderson is a petroleum geologist, and her job is to analyze data to determine where the best locations are to drill for oil and gas.

Oil and gas are both fossil fuels—nonrenewable energy sources that formed millions of years ago from plant and animal matter. They are nonrenewable resources because they take millions of years to form and therefore cannot be replenished in a short time.

The search for oil and gas is a part of geology because some of the processes that shape Earth’s surface—including the movement of tectonic plates and the processes that power the rock cycle—are also responsible for the formation of fossil fuels. Petroleum geologists like Shar Anderson use what they know about the movement of the tectonic plates and the properties of different rocks to gather data using a variety of different tools. They then analyze the data for patterns in Earth’s geology that might indicate the presence of fossil fuels.

These scientists analyze the properties of Earth materials for the presence of fossil fuels. This is important because fossil fuels, like many natural resources, are not distributed evenly around the planet. They are formed through specific natural processes, and those processes help to determine where fossil fuels can be found.

Finding fossil fuels begins with an understanding of how interactions between the geosphere and the biosphere caused them to form. Millions of years ago, oceans covered most of Earth. The oceans were home to tiny sea animals and plants called plankton. Like all living things, these plants and animals had chemical potential energy stored in their bodies.

When those organisms died, they sank to the bottom of the ocean. Sand and silt covered their remains. Over millions of years, the same pressure and heat that caused the sand and silt to turn into sedimentary rock also caused chemical reactions that broke the organic matter down into more basic structures.

The breakdown of the organic matter led to the creation of hydrocarbons— chemical compounds made up of hydrogen and carbon. Crude oil is one kind of fossil fuel that is made of heavy and complex hydrocarbons. It is a liquid that is found in underground reservoirs and remains a liquid when it is brought to the surface. Natural gas is another fossil fuel that is made of light and simple hydrocarbons. It is found wherever there is crude oil, but it can be found on its own as well. Coal is a third fossil fuel that was formed when ferns and other tree-like plants died and became buried by layers of sediment.

 

The Search for Fossil Fuels

So geologists use a variety of instruments to help them in their search. For example, they look for evidence of source rock, reservoir rock, and cap rock. They also look for deposits of salt because salt indicates that there used to be an ocean. Because of how fossil fuels are formed, evidence of an ocean suggests that fossil fuels might be found there. They also analyze surface features, surface rock and soil types. River deltas, deserts, and Arctic areas hold most of the oil and gas in the world today.

Geologists can also use seismic shock waves to find oil and gas reserves. The shock waves travel beneath Earth’s surface. When they come into contact with various rock layers, they are reflected back. The reflections travel at different speeds depending upon the type or density of rock layers through which they must pass.

Geologists use instruments called hydrophones to capture information about the shock waves, and then interpret the data to look for signs of oil and gas traps. Once geologists find a possible oil and gas trap, they can mark the location using GPS coordinates on land or with a buoy on water.

If it sounds as if a rock might contain oil or natural gas, the companies begin to drill to release the oil and gas from the rocks, which are often far below Earth’s surface. Oil sources are often found below the ocean floor, so oil companies have developed technologies that allow them to drill offshore.

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Refining Oil

Finding the oil is just one part of the process. The next step is removing it from the ground, and then refining it so it can be used. When crude oil is taken from the ground, it contains hundreds of different types of hydrocarbon chains that are all mixed together. There are four main ways to change hydrocarbons.

  • organizing molecules by size
  • breaking down large molecules into smaller ones
  • combining small molecules to produce larger ones
  • changing the shape of the molecules

The length of the chain of atoms in the molecule determines certain properties. As the hydrocarbon molecules get longer, they move from a gas to a liquid. Hydrocarbons with up to four carbon atoms are gasses.

 

How Fossil Fuels Are Used

Fossil fuels play an important role in our society. They are a primary source of energy, and are used to power many vehicles, electronics, and many other modern conveniences.

The reason that fossil fuels are an energy source goes back to the chemical potential energy that the organic matter holds within it. When fossil fuels are burned, that stored energy is released in an exothermic reaction. Exothermic reactions give off energy, making the surrounding temperature warmer. Exothermic chemical reactions that burn fossil fuels are some of the primary sources of energy in the United States today.

Refineries take the crude oil and turn it into gasoline and many other useful petroleum products. Petroleum refers to both crude oil and the products extracted from it at petroleum refineries. Petroleum is used in a wide range of consumer goods, such as detergent, fertilizer, synthetic fibers, vitamins, plastic, CDs and DVDs, candle wax and Band-Aids. Synthetic materials are those materials formed through a chemical process developed by humans, as opposed to those of natural origin.

The length of the chain of atoms in the molecule determines certain properties. As the hydrocarbon molecules get longer, they move from a gas to a liquid. Hydrocarbons with up to four carbon atoms are gasses.

 

Hands-on Science Activity

In this lesson, students use maps as models to evaluate the phenomena of the distribution of oil and natural gas reserves in the U.S. Then, they analyze the physical properties of sedimentary rock samples to figure out how oil and natural gas can be stored and contained within Earth.

Science Assessments

KnowAtom incorporates formative and summative assessments designed to make students thinking visible for deeper student-centered learning.

  • Vocabulary Check
  • Lab Checkpoints
  • Concept Check Assessment 
  • Concept Map Assessment 
  • And More...

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Science Standards

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Standards citation: NGSS Lead States. 2013. Next Generation Science Standards: For States, By States. Washington, DC: The National Academies Press. Neither WestEd nor the lead states and partners that developed the Next Generation Science Standards were involved in the production of this product, and do not endorse it.