Gas (n) ? a substance that doesn?t
have a fixed shape; also called a vapor.
Geology (n) ? the science of the history of the earth and its
life as recorded in rocks.
Geothermal energy (n) ? a renewable source of energy that comes
from heat found under the Earth?s surface.
Glacier (n) ? a huge mass of ice that moves slowly over land.
Global warming (n) ? an increase in the average temperature of
the Earth?s atmosphere.
Grass (n) ? Any numerous plants with narrow
leaves, hollow, jointed stems and spikes or clusters of membranous
Greenhouse Effect/Global Warming (n) - The greenhouse effect is a natural phenomenon that occurs when certain gases in the atmosphere, especially water vapor, carbon dioxide and methane, cause the Earth?s surface to heat up more than it otherwise would, thereby maintaining a global average temperature warm enough to support a rich variety of life. Global warming occurs when the amounts of carbon dioxide and other such gases in the atmosphere increase beyond natural levels, thereby intensifying the greenhouse effect.
Ground water (n) ? fresh water found beneath the Earth?s
surface, usually in aquifers.
Gulf (n) ? a large area of sea or ocean partially enclosed by