Mrs. Storiz Mountains & Volcanoes

Terms	Definitions
mountain	an area of land that rises steeply from the land around it.
mountain range	long lines of mountains that were formed at about the same time an by the same processes.
mountain belt	ranges that are close together.
tectonic plate boundaries	where most of the world's mountain belts are located.
location of Appalachian mountains	interior of plate
Appalachian mountains formed by	ancient plate collisions
folded mountain	forms as continental crust crumples and bends into folds. Form as oceanic plates sink under the edge of a continent or as continents collide.
Himalaya mountains	example of folded mountain. Formed when the India plate collided with the Eurasian plate.
fault block mountains	mountains that form as blocks of rock move up or down along normal faults.
volcano	an opening in Earth's crust through which molten rock, rock fragments, and hot gases erupt. A mountain built up from erupted material.
violent eruption	can cause tremendous destruction even if not much molten rock reaches the surface.
silica	a major portion of all magma, which is a compound of silicon and oxygen. Magma high in this resists flowing, so expanding gases are trapped in it.
volcanic eruptions occur	when a chamber is not large enough to hold additional magma that pushes in.
lava	magma that has reached the Earth's surface.
volcanic ash	consists of particles ranging from the size of dust to about rice grains.
volcanic cinder	contains holes and tunnels left by escaping gases. Larger than ash.
volcanic bombs	molten when they are thrown out of a volcano and often have a streamlined shape.
volcanic blocks	can be the size of a house, erupt as solid pieces of rock.
main gases in magma	water vapor and carbon dioxide.
pyroclastic flow	a dense cloud of super hot gases and rock fragments that races downhill. Most dangerous, can travel faster than 160 km/hr and as hot as 800 degrees C.
Ring of Fire	volcanoes around the Pacific Ocean form a belt
Shield volcano	shaped like a broad, flat dome. It is built up by many eruptions of lava that is relatively low in silica and therefore flows easily and spreads out in thin layers.
Mauna Loa	Largest shield volcano, located in Hawaii. Most active.
Cinder Cone	is a steep, con-shaped hill formed by the eruption of cinders to other rock fragments that pile up around a single crater. May form on the sides of other types of volcanoes.
Composite volcano	a cone shaped volcano built up of layers of lava and layers of rock fragments. It's magma is high in silica and therefore pasty. Steep near top and flattens out toward the bottom.
reasons for violent eruptions	1. expanding gases trapped in rising magma. 2. hardened lava from earlier eruptions often plugs openings in these volcanoes. The rock must be blown out of the way before any magma can escape.
caldera	a huge crater formed by the collapse of a volcano when magma erupts from underneath it. Formed by both shield and composite volcano and can then fill with water from melted snow and ice.
volcanic activity indicators	magma moving underneath, earthquake activity and changes in the tilt of the ground. Also monitor springs and lakes as well as amounts of gas and type of gas given off.
geyser	forms where water collects in an underground chamber, then erupts through a narrow channel.
fumarole	similar to a hot spring. Instead of liquid water, releases steam and other gases.
deep sea vents	are hot springs that form at spreading centers in the ocean. The water coming out of the ocean floor is rich in dissolved minerals and gases from the rock and magma. Support unusual life forms.
magma chamber	inside a volcano where magma collects in a pocket.
pipe	a long tube that connects the magma chamber to the Earth's surface.
vent	where the magma leaves the volcano through this opening.
crater	bowl shaped area around a volcano's central vent.
dormant	not active now but a volcano may become active in the future.
extinct	volcano is not likely to erupt again.
pahoehoe	Pahoehoe is a Hawaiian term for basaltic lava that has a smooth, hummocky, or ropy surface. A pahoehoe flow typically advances as a series of small lobes and toes that continually break out from a cooled crust. The surface texture of pahoehoe flows varies widely, displaying all kinds of bizarre shapes often referred to as lava sculpture
aa	A'a' lava is the most common appearance type of lava flows that cool down forming fragmented, rough, sometimes spiny, or blocky surfaces.