melted rock cools and hardens, forming what?
igneous rocks
a material on Earth that is necessary or useful to people
natural resource
a resource that can be used over and over
renewable resource
harmful things in the air
pollution
mineral property identified by the color of the powder left behind when it is rubbed across a surface
streak
a rock that is formed by layers of sediment
sedimentary rock
topsoil
energy from the sun
solar energy
water held in rocks below ground
groundwater
how light reflects off of a mineral
luster
rocks changed by heating and squeezing
metamorphic rocks
tiny bits of rock or dead plant and animal matter
sediment
a resource that takes millions of years to form and cannot be easily replaced
nonrenewable resource
where is most of Earth's water located?
oceans
impressions that living things leave behind in mud
imprints
salt is a type of what?
mineral
humus
the remains or traces of something that lived long ago
fossils
making resources last longer
conservation
what are fossil fuels?
coal, natural gas, oil
another name for a valuable mineral such as a diamond or ruby
gem
what is the top layer of soil that is solid rock
bedrock
energy used in homes or cars
fuel
what are the renewable resources
plants, water, air
what are water sources that contain fresh water?
glaciers, groundwater, lakes, rivers, ponds, streams