Soil, Rocks, and Minerals Notes
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Recognize and describe materials that come from the earth’s
surface.
Recognize that rocks are made up of minerals.
Explain how fossils provide evidence of Earth’s past.
Identify earth materials used to construct some common objects.
Describe how materials from the earth can be used as fuels for
heating and transportation.
soil- A natural material consisting of small particles (pieces) of rock,
material from decaying plants and animals, minerals, water, and air.
humus- (hyoo mus) Leftover decomposed (rotted) plant and animal material.
Different types of soils have different properties.
These properties are:
 texture- size of the soil particles (pieces)
fine =small
medium = mid-sized
coarse = large
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mineral content- The type of minerals depend on the type of rock it was
made from. Water can dissolve or wash away minerals. Plants also use up
minerals in the soil to make their food. Farmers often add fertilizer to
replace minerals washed away or used up.
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composition and place formed- The material the soil is composed (made
up) of and the place the soil was made. It may have been moved by man,
glacier, or erosion (wind and water)
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thickness- The depth (thick or thin) of the layer of soil.
Soil is found in layered in nature. Each layer is called a horizon. All of the
layers (horizons) in order make up the soil profile. Typically the soil profile
is:
 topsoil- Top layer of soil, rich in humus and minerals, usually dark in color.
It is best for growing most plants, most plants and organisms live here.
 subsoil- A fairly hard layer made of clay and minerals from the topsoil,
light colored.
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bedrock pieces- Coarse broken up bedrock, usually deeper than plant
roots. Bedrock is the hard rock under the soil.
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boulder- Large rock, much larger than gravel. Standing alone, not connected
to other rocks, and usually worn or rounded by weathering.
gravel- Small, rounded pieces of rock, larger than soil.
sand- A type of soil. It has the most coarse (largest) particle size and high
permeability (water moves through quickly).
silt- A type of soil. It has medium texture (medium sized particles) and
medium permeability.
clay- A type of soil. It has the finest (smallest) particle size and low
permeability (water passes through slowly).
loam- A mix of humus, sand, silt and clay in which plants grow very well. Loam
differs according to the amount of the soils, different plants grow best in
different soil types.
pore space- The space between soil particles, filled with water or air.
permeability- The rate (speed) at which water can pass though a material.
Rocks can be broken down into soil by chemical or physical weathering.
(An example of chemical weathering is chemicals dissolved in rain -called
acid rain.)
(Examples of physical weathering are freezing and thawing, growing plants,
and flowing water.)
Soil is considered natural if it has been unchanged by humans.
Soil is considered manufactured if humans have added items to it such as
fertilizer.
Rich soil is very important for growing crops. It will allow the plants to grow
larger and produce more food.
Different crops use and add different nutrients to the soil. Farmers can
rotate the crops they plant in a field. This helps to prevent using up all of a
needed nutrient and having to replace it with a fertilizer. For example, if
crop A uses a lot of nitrogen and crop B replaces nitrogen in the soil, then by
alternating the two crops on the field, there will be enough nutrients for
both crops to grow well.
Rocks and Minerals
mineral- Naturally occurring substance, neither plant nor animal, each has
unique properties
rock- Hardened, non-living material that makes up the crust of the earth,
made up of two or more minerals
sedimentary rock- Rock formed from bits or layers of rocks cemented
together
igneous rock- “Fire-made” rock formed from melted rock material from the
mantle that has cooled.
metamorphic rock- Rock whose form has been changed by heat or pressure
rock cycle-The process by which rocks are changed from one type to
another
Rocks are used in many ways and hold clues to Earth’s past. Rocks and
minerals are used to create many everyday items. For example, bricks are
clay and rock, glass is sand and limestone, concrete is sand and rock and
many, many others.
Fossils
fossil- The hardened remains or marks of a living thing that died millions of
years ago; Latin- meaning “dug up”
cast- A fossil formed or shaped in a mold; it looks like the actual object
mold- A hollow fossil form clearly showing the outside features of an
organism
amber- Hardened tree sap, often a source of insect fossils
Fossils are formed/found in sedimentary rock.
Fossils give us clues to life in the past. some examples are: size, diet,
habitat, age, number of legs walked on,
Only a very small fraction of plants and animals become fossils. Special
conditions must exist in order for remains to be preserved.
Organisms can also be preserved in tar pits, by freezing, mummification,
carbon film, and petrification.
Fossil fuels (fuel created from remains of ancient life) are used in many
ways, especially for heating and transportation. Materials that can be used
as fuel include oil, natural gas, and coal. Crude oil is used to make gasoline
for cars.