All terms in this list:

core: the dense center of the earth made of solid and molten iron and nickel

mantle: the layer of the earth that surrounds the core; made of both molten magma and solid rock

crust: the thin, solid, rocky outermost layer of the earth

Viscosity: the ability of a substance to resist flowing

Tectonic forces: forces generated from within the earth that result in uplift, movement, or deformation of the earth’s crust

Primordial: the original as it was in the very beginning of its formation

Focus: the point inside the earth where rock first moves, starting an earthquake

Epicenter: the point on the earth’s surface directly over the focus of an earthquake

Convection current: the circular flow of magma within the molten part of the mantle as it heats up and cools down

Oceanic trench: geologic feature formed in the oceans at convergent boundaries where subduction zones exist

Deformation: the process of physically changing the earth’s crust as a result of tectonic forces

Continental margin: the edges of the continents below sea level that represent the shallowest parts of the oceans

Plate boundary: an area on the earth’s surface where the edges of tectonic plates are interacting

Subduction: the geologic process by which one tectonic plate is forced downward into the mantle under another tectonic plate forming an oceanic trench

Volcanic arc: an arcing chain chain of volcanic islands or volcanic mountains formed by the subduction of an oceanic plate into the mantle under another tectonic plate

aleutian islands: an arc shaped chain of small volcanic islands off the coast of alaska formed by subduction processes along an oceanic convergent boundary

Cascade mountain range: active volcanic mountain range located in the northwest united states formed by the subduction zone between the Juan de Fuca and north american plates that produces volcanic hazards for california

Mid ocean ridge: underwater mountain range that is hundreds of miles long in the middle of the ocean providing evidence that earth’s ` tectonic plates are moving away from each other at a divergent plate boundary as mantle magma rises to form new crust

Mid Atlantic ridge: mid ocean ridge in the middle of the Atlantic ocean responsible for pushing apart the continents of Africa and S. America

Plate tectonics: the theory that the earth’s surface is made of large sections of crust that move and interact with each other

ring of fire: an area of high subduction activity and frequent volcanic eruptions surrounding the pacific plate

Basaltic magma: thin, fluid, runny magma having low viscosity, low silica content (SiO2), small amounts of dissolved gases, and high concentrations of iron and magnesium that produces quiet, non explosive, voluminous eruptions

Rhyolitic magma: very thick and sticky magma having high viscosity due to cooler temperatures, high silica content (SiO2) high gas content, and low concentrations of iron and magnesium that produces extremely violent volcanic eruptions

continental drift: the theory originally proposed by alfred wegener that the major landmass of the earth were once part of one large single supercontinent that broke apart 200 million years ago

diffraction: the process of earth materials separating and sorting by density resulting in a layered
Structure with the densest material (FE & Ni) setting in the core

tectonic plate: a large section of the earth crust that moves and carries everything on it

hotSpot: a stationary high temperature area of melting within the earth’s mantle that can last for several millions of years where superheated mantle magma rises towards the surface

Rift valley: along narrow rip or opening made by the stretching pulling or splitting apart of the earth’s crust along divergent plate boundaries through which mantle magma reaches the surface

sea floor spreading: the theory that oceans widen (open up)and continents are pushed part as new oceanic crust is formed along the crest of mid -ocean ridges at divergent plate boundaries where tectonic plates are moving away from each other

paleomagnetism: a record of the earth's magnetic field preserved by the alignment of magnetic minerals in the rocks of earth’s crust at the time that the rocks were formed at mid-ocean ridges