- Faultsearch for term
A crack or fracture in the earth's surface. Movement along the fault can cause earthquakes or--in the process of mountain-building--can release underlying magma and permit it to rise to the surface.
- Fault Scarpsearch for term
A steep slope or cliff formed directly by movement along a fault and representing the exposed surface of the fault before modification by erosion and weathering.
- Felsicsearch for term
An igneous rock having abundant light-colored minerals.
- Fire fountainsearch for term
A rhythmic vertical fountainlike eruption of lava.
- Fissuressearch for term
Elongated fractures or cracks on the slopes of a volcano. Fissure eruptions typically produce liquid flows, but pyroclastics may also be ejected.
- Flank Eruptionsearch for term
An eruption from the side of a volcano (in contrast to a summit eruption.)
- Fluvialsearch for term
Produced by the action of of flowing water.
- Formationsearch for term
A body of rock identified by lithic characteristics and stratigraphic position and is mappable at the earth's surface or traceable in the subsurface.
- Fracturesearch for term
The manner of breaking due to intense folding or faulting.
- Fumarolesearch for term
A vent or opening through which issue steam, hydrogen sulfide, or other gases. The craters of many dormant volcanoes contain active fumaroles.