F

facies
Characteristic sedimentary rock layers that indicate the processes and environments in which they were formed.
fault
A fracture along which one side has moved relative to the other.
felsic
A type of igneous rock that is made mostly of light minerals such as quartz and feldspar.
fissure
A crack in the ground that may be the site of a volcanic eruption.
flood
An overflow of water in a location.
focus
The point where rocks rupture during an earthquake.
fog
Air condensed below its dew point that is near the ground like a cloud.
fold
A bend in a set of rocks caused be compression.
foliation
Flat layers in rocks due to squeezing by pressure.
food chain
An energy pathway that includes all organisms that are linked as they pass along food energy, beginning with a producer and moving on to consumers.
food web
Interwoven food chains that show each organism eating from different trophic levels.
fossil
Any remains or trace of an ancient organism.
fossil fuel
A hydrocarbon created from the remains of formerly living organisms that can be used for energy.
fossilization
The process of becoming a fossil.
fractional crystallization
The crystallization of a fraction of the minerals in magma depending on temperature.
fracture
(minerology) The way a mineral breaks when it is not broken along a cleavage plane.
(structural geology) A break in rock caused by stresses, with or without movement of material.
frequency
The number of wavelengths that pass a given point every second.
fresh water
Water with a low concentration of salts; found in streams, lakes, ground, ice, atmosphere.
front
The meeting place of two air masses with different characteristics.
fuel
Material that releases energy as it changes chemically.
fuel cell
An energy cell in which chemical energy is converted into electrical energy.