apes chapter 8

what is the earth’s core composed of?

iron and nickel

what layer of the earth is above the core?

mantle

what is in the mantle?

magma, circulating in convection cells

outer part of the mantle?

asthenosphere

what is in the asthenosphere?

semi-molten ductile rock

what is the crust?

chemically distinct outermost layer

how are hot spots formed?

molten material from the mantle reaches the lithosphere

the theory that the lithosphere is divided into plates, most of which are in constant motion

plate tectonics

the sum of the processes that build up and break down the lithosphere

tectonic cycle

define seismic activity

frequency and intensity of earthquakes over time

how are rocks formed?

magma reaches the surface, cools, and hardens

what are the three distinct rock types?

igneous sedimentary metamorphic

what are the two types of chemical composition igneous rocks can have?

basaltic or granitic

what are the two modes of formation igneous rocks can have?

intrusive or extrusive

how are sedimentary rocks formed?

sediments are compressed by overlying sediments

how are metamorphic rocks formed?

rocks subjected to high temperature and pressure

how is pressure exerted on metamorphic rocks?

overlying rock layers or tectonic processes