Geology Wec Revsion Flash Cards

Front 1

GL1 - key idea 1
list all the differences between the oceanic crust and the continental crust !

Back 1

oceanic crust: rich in Fe and Mg, contains basalt (pillow lavas), dolerite (dykes), Gabbro (layers), its density is 2.9 g/cm3, oldest oceanic crust is 200 ma & average thickness is 7km.
Continental crust : rich in Al and Si, contains granitic rocks and igneous, metamorphic & sedimentary rocks. average density is 2.7 g/cm3, all ages up to 4000 ma and the average thickness is 35 km.

Front 2

GL1 - key idea 1
what is the composition and physical state of the mantle? upper and lower mantle.

Back 2

upper mantle - solid but less dense than lower mantle, composition- main rock is peridotite.
Lower mantle-solid, composition - silicate materials same types as stoney meteorites.

Front 3

GL1 - key idea 1
How do meteorites and S-waves provide evidence for the internal structure of the earth ?

Back 3

meteorites provide evidence as they are compoesed of the same stuff and have the same age. Iron - core
stoney -mantle
seismic waves cannot pass through liquid, the outer core is liquid this is proven as s-waves cant pass through outer core (SHADOW ZONE)

Front 4

GL1- key idea 1
what is the composition and physical state of the inner and outer core?

Back 4

inner core - solid material due to extreme pressure, evidence: p & s waves travel through, composition-iron nickel based on meteorite evidence.
outer core-liquid iron nickel- s waves cannot pass through, pressure is less then inner core allowing liquid to exist.

Front 5

GL1- key idea 1
explain the nature of the mohorovicic discontinuity ?

Back 5

The Mohorovicic Discontinuity, or "Moho", is the boundary between the crust and the mantle.this boundary marks the compositional change between crust and mantle.