basaltic rocks that contain a high percentage of ferromagnesian minerals are called this
Describes magma or igneous rock that is rich in feldspars and silica and that is generally light in color.
Intermediate in composition between mafic basalt and felsic rhyolite,
A fine-grained, felsic, igneous rock made up mostly of feldspar and quartz.
dense, dark-colored igneous rock formed from magma; rich in magnesium and iron and poor in silica
A tectonic plate boundary where two plates collide, come together, or crash into each other.
the boundary between two tectonic plates that are moving away from each other
a plate boundary where two plates move past each other in opposite directions
The theory that evolution occurs slowly but steadily
Scottish geologist who described the processes that have shaped the surface of the earth (1726-1797)
a dense sphere of solid iron and nickel at the center of Earth
a layer of molten iron and nickel that surrounds the inner core of Earth
the layer of the earth between the crust and the core
the solid part of the earth consisting of the crust and outer mantle
a mineral consisting of magnesium iron silicate
The solid, plastic layer of the mantle beneath the lithosphere; made of mantle rock that flows very slowly, which allows tectonic plates to move on top of it
the region where an oceanic plate sinks down into the asthenosphere at a convergent boundary, usually between continental and oceanic plates
is the idea that the geologic processes that operate today also operated in the past
denser plate made mostly of basalt
tectonic plate that lies under a continent
Continental Volcanic Arc
mountains formed by igneous activity associated with the subduction of oceanic lithosphere beneath a continent
these eruptions produce clouds and avalanches of pyroclastic debris and happen when gas expands in the rising magma but cannot escape, eventually the pressure becomes so great that it blasts the lava out of the volcano
The pocket beneath a volcano where magma collects.
a material found in magma that is formed from the elements oxygen and silicon
indicates the destructiveness of a volcano
Thick, high viscosity, rubble-like lava.
- Explosive activity
- Intermediate (60%) silica content.
Steep-sided, loosely packed volcano formed when tephra falls to the ground
bits of rock or solidified lava dropped from the air
magma that reaches the Earth's surface
a wide, gently sloping mountain made of layers of lava and formed by quiet eruptions
pebble like bits of magma that cool in the air
Extremely small fragments, usually of glass, that form when escaping gases force a fine spray of magma from a volcano.
A projectile of hot magma or rock that is blown from the vent during a volcanic eruption. These solidify in flight and frequently form an elongated rock of streamlined shape.
Large pieces of pyroclastic material that is made up of rock.
Volcanic Hazards: Explosives, Ash, Gas, Lava, Earthquakes, Tsunamis
how frequently a flood of 'x' severity occurs in average for that particular stream
a volcanic eruption in which a stream of gas and ash is violently ejected to a height of several miles
Mainly associated with felsic magmas, marked by glowing clouds- downslope
a large crater caused by the violent explosion of a volcano that collapses into a depression
an area where magma from deep within the mantle melts through the crust above it
A mudflow composed of water and volcanic ash. Lahars can be triggered by the flash melting of the snow cap of a volcanic mountain or from heavy rain. Lahars are very dangerous because they can occur suddenly and travel at great speeds.
Fiery pyroclastic flow made of hot gases infused with ash and other debris. Move down the slopes of a volcano at speeds up to 200 km per hour (125 ish miles per hour)
mid Ocean Ridge
An undersea mountain chain where new ocean floor is produced
The process that created the Earth's magnetic field. The Earth got so hot that the molten iron got stuck as the planet's core because of density.
(cosmology) the theory that the solar system evolved from a hot gaseous nebula
a vertical geyser of lava which shoots dozens of yards up into the air from a narrow conduit
a vent in a volcanic area from which fumes or gases escape
Ring of Fire
Collection of volcanoes rimming the Pacific Ocean, really a ring of subduction zones
the probability that an event will occur given that oneor more other events have occurred
Frequency v Magnitude
The greater the magnitude of a disaster, the lower the frequency
a principle that states that geologic change occurs suddenly
the boundary between the earth's mantle and crust
the hypothesis that the continents slowly move across Earth's surface
a valley formed when the block of land between two normal faults slides downward
A volcanic eruption emanating from an elongated fissure rather than a central vent.
San Andreas Fault
a huge crack that runs through most of California that separates the North American and Pacific plates
a mound of felsic lava which may form inside a crater; a kind of cap over the vent.
Partial melting of hot mantle rock when it moves upward and the pressure is reduced to the extent that the melting point drops to the temperature of the body.
An explosion in which the energy released is directed horizontally instead of vertically as in a regular eruption.
vast, sheetlike deposit of felsic pyroclastic materials erupted from fissures
a slow-moving type of lava that hardens to form rough chunks; cooler that pahoehoe
a hot, fast-moving type of lava that hardens to form smooth, ropelike coils
high content is more viscous (thick, andesitic/rhyolitic) low content is less (thin, basaltic)
Predictions Based on Precursors
Tilt Meters/GPS, Earthquakes, Temperature changes, Changes in Gas Composition, other geophysical methods
Age of the Earth
4.5-5 billion years
lava and cinders, moderate magma volume, moderate violence, composite or cinder cone, sporatic violence
*type of eruption
-dense cloud of ash-laden gas explodes from the crater and rises above the peak
-steaming ash forms a whitish cloud near the upper level
-Paricutin Volcano in 1947