Question | Answer |
continental drift | the theory that the continents have drifted slowly over time to their current locations. |
Pangaea | the giant landmass of 200 million years ago that broke apart; meaning all land |
sea floor spreading | the 1960 theory of Harry Hess, proposing that hot, less dense material below the earth's crust rises up to th surface at mid-ocean ridges. |
plate tectonics | theory that staes the Earth's crust and part of the upper mantleare broken into sections. |
plate | these move on a plastic-like layer of the mantle |
lithosphere | the crust and the upper mantle |
asthenosphere | plastic-like layer below the lithosphere |
convection current | a cycle of heating, rising and cooling within the Earth's interior |
earthquake | the product of tremendous energy released as rocks break and move apart |
fault | the surface where a break in rock has occured |
seismic wave | waves transmitted through the Earth's materials and along it's surface |
focus | the point inside the Earth where movement first occurs and the energy is released |
seismograph | an instrument used to record the seismic waves of an earthquake |
magnitude | the height of lines on a seisomograph; a measure of the energy released by an earthquake. |
tsunamis | an earthquake that begins on an ocean floor, causing powerful water waves to be produced |
seismic safe | a building will have this certification if it will stand up to against the vibrations caused by earthquakes |
volcanoes | rising magma that leads to an eruption, where magma, solids, and gases are spwed from the top. |
lava | magma as it flows to the top of the earth's surface. |
shield volcano | broad volcano with gently sloping sides |
cinder cone volcano | top less than 300 m and forms in groups near other volcanoes |
composite volcano | steep-sided mountains composed of layers lava and tephra |
tephra | solidified lava, ash, and cinders |
rift | long cracks that form between plate boundaries as they separate |
hot spot | large, hot, rising bodies of magma that rise through the arth's crust and mantle |
convergent boundary | a place where tectonic plates move towards one another |
divergent boundary | a place where tectonic plates move away from each other |
transform boundary | a place where tectonic plates grind past one another |