| A | B |
|---|
| absolute age | the age of a fossil in years |
| alternative energy source | any source of energy other than fossil fuels - wind, moving water, sun |
| aquifer | an underground layer of rock or soil that has pores and is capable of absorbing water |
| conservation | making resources last longer |
| era | a unit of time measured in millions of years |
| fossil | remains of something that lived long, long ago like bones |
| fossil fuel | a material that formed from the decay of ancient organisms and is used today as a source of energy |
| hardness | a measure of how well a mineral resists scratching |
| humus | tiny bits of rock or dead plant or animal matter |
| igneous rock | melted tock that cools and hardens like granite |
| luster | the way a mineral reflects light from its surface |
| metamorphic rock | rock formed from other rocks by extreme heat and pressure like marble |
| mineral | natural, nonliving, usually solid material found in rock |
| nonrenewable resource | a useful material that cannot be replaced or reused easily |
| ozone | a layer of gas above the Earth's surface that protects living things on Earth |
| pollution | what happens when harmful things get into the water or air and can make living things sick |
| relative age | age of one thing compared to another thing |
| renewable resource | a useful material that can be replaced quickly in nature like wind |
| reservoir | storage area for holding water from a different area and has water safe to drink |
| rock cycle | rocks change from one form to another |
| sedimentary rock | rock that is formed from layers of sediment like sandstone |
| smog | type of air pollution |
| soil | a mixture of bits of rock and bits of dead parts of plants & animals |
| soil horizon | layers of soil divided into three sections |
| topsoil | the dark, top layer of soil, rich in humus and minerals and home to many living things |
| cleavage | the number of planes along which a mineral breaks |
| conglomerate rock | made from smaller rounded stones that have been cemented together |
| crystal | a solid whose shape forms a fixed pattern |
| extrusive rock | forms rapidly from lava on the Earth's surface - pumice |
| fracture | the property a mineral shows when it has uneven or rough surfaces |
| gem | a mineral that is rare, beautiful, usually transparent, and glitters or shines in light |
| geothermal energy | heat produced inside the Earth |
| intrusive rock | forms slowly from magma inside the Earth - granite |
| irrigation | a way to bring water into the soil through pipes or ditches |
| nuclear energy | heat produced from atoms |
| ore | a useful rock that contains a mineral |
| organic | having to do with or coming from living things |
| fresh water sources | running water, standing water, groundwater |
| conservation practices | fertilizing, crop rotation, strip farming, contour plowing, terracing, wind breaks |
