| A | B |
|---|
| Abrasion | wearing away of rock by grinding action |
| Absolute time | method of recording events that identify when a rock formed |
| acid rain | rain that contains dissolved sulfer or nitrogen gasses |
| air pressure | weight of the atmosphere per unit area |
| anemometer | instrument to measure wind speed |
| aquifer | permeable earth material that carries groundwater |
| average slope | the slope or gradient between any two points on a hill |
| barometer | an instrument that measures atmospheric pressure |
| carbonic acid | a weak acid formed when carbon dioxide dissolves in water |
| chemical weathering | breakdown of rock that takes place when minerals are changed into differnt substances |
| chromosphere | the layer of the sun's atmosphere just above the photosphere |
| cleavage | the tendency of a mineral to split easily |
| condensation | change from water vapor to liquid water |
| contour line | line on topographic map that connects ponts on land having the same elevation |
| delta | a fan shaped deposit of sediment formed at the mouth of a stream |
| density | ratio between mass and volume of a substance |
| dew | water vapor that condenses on a surface as a liquid when air is saturated |
| evaporation | change of liquid water to water vapor |
| feldspar | one of the most common of all minerals; formed by silica, aluminum and other metals |
| focus | point at which the earthquake originates |
| fracture | apperance of a mineral where it breaks other than cleavage planes |
| front | the boundary between two unlike air masses |
| greenhouse effect | the ability of Earth's atmosphere to absorb long heat waves from Earth after allowing the sun's short waves to pass through |
| hypothesis | possible explanation for an event which is based on information |
| igneous rock | rock formed by the solidification of hot molten rock called magma |
| impermeable | rock material through which water does not pass easily |
| light year | the distance a ray of light travels in one year, about 9.5 trillion kilometers |
| luster | the way a mineral reflects light |
| meridian | an imaginary half-circle that runs in a north-south direction |
| metamorphic rock | rocks formed by the effect of heat,pressure and chemical action on other rocks |
| moraines | accumulations of glacial till |
| nebula | a large cloud of gas and dust in space |
| oxidation | the chemical reaction of oxygen with other substances |
| profile | a line that shows changes in elevation across a topographic map |
| radiation | transfer of heat in the form of short waves |
| rock | a group of minerals bound together |
| Richter Scale | a numerical description of an earthquake's magnitude |
| stratification | the arrangement of rock beds in visible layers |
| striations | scratches left on rock by glacier movement |
| weather | the state of the atmosphere at a given time and place |
