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Science
Ch. 7 – Notes
Lesson 1
- Rock: a natural, solid, nonliving material made of one or more
minerals
- Physical Properties of Rocks:
o color
o what minerals it’s made of
o texture (size of the minerals that make up rock)
- Types of Rocks:
- Igneous Rock:
- forms from a very hot mixture of melted minerals and gases
- if it is cooled rapidly above ground it will have smaller mineral
grains
- if it is cooled slowly below ground it will have larger mineral
grains
- Sedimentary Rock:
- formed from bits of rocky matter (sediments) that settle to the
bottom of river, lakes, and oceans
- over thousands of years, the sediments are pressed together
one layer at a time
- fossils of extinct plants and animals are found in these rocks.
older fossils are usually in the deeper layers
- Metamorphic Rock:
- Igneous or Sedimentary Rock that has been changed by heat
and pressure
Lesson 2
- Mineral: a natural material that forms from nonliving matter
- Properties of Minerals:
o color
o luster – how the mineral reflects light
o streak – color left behind when mineral is rubbed on a hard
surface
o hardness
* Best way to identify a mineral is by hardness and streak
- Minerals we use every day:
o halite – salt we use on our food
o copper – what some pots and pans are made of
o fluorite – in our toothpaste
o graphite – in our pencils
o iron – what some tools, cars, and machines are made of
o quartz – what some glass is made of
Lesson 3
- Soil: thin layer of loose materials that covers most of the Earth’s
surface
- Soil layers:
o Topsoil: top layer of soil that includes rock particles mixed
with the dark products of decay. Decayed parts of plants
and animals are humus. Humus contains the nutrients plants
need to grow.
o Subsoil: under topsoil. Includes pieces of broken rocks. Tree
roots grow in subsoil. Water from precipitation may be here.
o Bedrock: as this rock breaks down it provides raw material
for making new soil.
- Types of Soils:
o Sand: large particles. Water passes quickly through sand, so
roots do not have enough time to soak up water.
o Silt: medium particles. Holds water well.
o Clay: small particles. Water passes slowly through clay.
o Loam: made of sand, silt, and clay. Has high amounts of
decayed matter and minerals. Has good nutrients. Holds
on to water loosely enough for plants to soak it up.
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