tephra		rocks formed from sediments that have been pressed into rock
physical weathering		a break in rock at the boundary between two moving masses
crust		water, ice or windblown sand breaking down rock
sedimentary rock		the volcanic belt that encircles the edge of the Pacific Ocean
Ring of Fire		a trembling or shaking of the earth's crust
chemical weathering		top layer of the earth ranging 40 miles to 3 miles thick
core		breaking of rock without any movement at the break
Moho		the individual substances that make up rocks
fracture		sedimentary or igneous rock changed by heat or pressure
soil		the innermost region of the earth
magma		rocks that form when molten rock solidifies
epicenter		scale to measure the strength of an earthquake
magnitude		scientist who studies the earth
focus		the boundary between the crust and the mantle
tremor		melted rock
minerals		a weak earthquake
igneous rock		the point underground where an earthquake begins
earthquake		rocks that bend without cracking
fumaroles		the place at ground level directly above the focus
metamorphic rock		it's made up of humus and weathered rock
fault		lava fragments that solidify into rock instantly
seismologist		acids breaking down rock
geologist		a scientist who studies earthquakes
fold		an escape vent for underground gases near active volcanoes