Fossils, Fossil Fuels and Energy Resources Study Guide
FOSSILS
Fossils are the remains or impressions of plants or animals that lived long ago, such as mineralized
bones, shells, footprints, or leaf prints.
A plant or animal that no longer exists anywhere on the Earth is called extinct.
Scientists learn about extinct animals by observing and comparing fossils.
Paleontologists are scientists who study species that lived in the past.
Scientists around the world who share ways of thinking are called the scientific community.
Trilobites were hard-shelled arthropods with multiple body segments and jointed legs. Trilobites lived
in oceans all around the world, but are now extinct.
Trilobite 1
Trilobite 2
Fossil shark teeth were found in the same places as fossils of
Trilobite 2, and scientists have discovered that they lived at the
same time. No shark teeth have been found from the same time
and place as Trilobite 1.
What could you infer about these observations?
When sharks began to live in the oceans, they ate trilobites,
so trilobite species that had or developed spines were better adapted for survival. Trilobite
species without spines were reduced in numbers or died out completely.
When trilobite fossils are found with other fossils, scientists can use the known trilobite to identify the
age of the other fossils.
FOSSIL FUELS
Coal, oil, and natural gas are called fossil fuels. Oil is also called petroleum.
Oil comes from microscopic plants and animals in the ocean that died millions of years ago.
(o-o-o oil-ocean-organisms)
Coal comes from fossil remains of giant ferns and trees that lived millions of years ago.
(la-la-la coal-land-plants)
Coal, oil, and natural gas are made from four main ingredients:
• dead plants and animals that are covered with many layers of sediment
• lots of pressure from the weight of many layers of sediment
• lots of heat from all the layers of sediment
• millions of years of time
The energy in fossil fuels originally came from the Sun. Plants use the energy in sunlight to make
their own food. The energy in plants passes to the animals that eat the plants. Some energy remains
in plants and animals that die and become fossil fuels. Burning the fossil fuels releases the energy
for humans to use. This energy heats our homes, generates electricity, and powers our cars.
Burning of fuels creates air pollution, which can cause acid rain and health problems such as lung
disease. Burning fossil fuels for energy also releases large amounts of carbon dioxide into the
atmosphere, which many scientists believe may be contributing to global warming.
SEDIMENTARY ROCK
Most of the rocks that form layers at Earth’s surface are sedimentary rocks.
A sedimentary rock is made of bits of other rocks called sediments. Sediments form layers at the
bottoms of valleys and seas.
The oldest rock layers are at the bottom, and the youngest rock layers are at the top.
Compaction happens when sediments are packed tightly together.
Cementation binds the sediments together to form a rock.
Fossils are usually found in sedimentary rock layers.
ENERGY RESOURCES
Alternative energy sources are any sources of energy that are not from fossil fuels.
A nonrenewable resource is any natural resource from the Earth that exists in limited supply and
cannot be replaced if it is used up. Oil, natural gas, coal, and uranium are nonrenewable energy
resources. We use them up faster than they can be made by nature.
Nuclear energy is energy in the nucleus (core) of an atom. The most common fissionable atom is
uranium-235, which is the fuel used in most types of nuclear reactors today. Nuclear energy is
nonrenewable because there is a limited supply of uranium in the Earth.
A renewable resource is any natural resource that can replenish itself naturally over time. Solar,
wind, water, geothermal, and biomass are renewable energy resources.
Solar energy is energy from the sun in the form of radiation. A solar cell can convert sunlight into
electrical energy, and is typically made of layers or sheets of silicon. A dark-colored solar panel will
absorb more radiation than a lighter color.
Windmills change the wind’s energy into power (mechanical energy). The power is used to grind
grain, pump water, produce electricity, and do many other jobs. A wind turbine is a streamlined
windmill that produces electricity. Groups of larger wind turbines are called wind farms.
Biofuels are obtained from organic materials (biomass), such as wood and agricultural crops. They
can be burned directly or processed into fuels such as ethanol and methane.
Geothermal energy is a form of energy obtained from the Earth's internal heat, usually near
volcanoes or other hot spots on the surface of the Earth. The Earth can heat water until produces
steam. The steam can be used to turn turbines of generators to produce electricity.
Hydroelectric energy is power that is derived from the force of moving water, such as rivers or
ocean tides. The moving water can be used to turn turbines of generators to produce electricity.
Advantages of Alternative Energy: Alternative energy sources are a lot cleaner for the
environment and are renewable. We will never run out of them.
Disadvantages of Alternative Energy: Energy from alternative resources is more expensive
than using fossil fuels. Some alternative energy sources can only be used in certain places
(windy areas for wind turbines, sunny places for solar panels, “hot spots” for geothermal, rivers or
oceans for hydroelectric).