worksheet 5

Question 1

when was pangea

Answer 1

started approx 320 mya

Question 2

where was ireland during pangea

Answer 2

near the tropic of cancer at 25-30ºN (where the sahara is today)

Question 3

what was the super-ocean around pangea and how wide was it

Answer 3

panthalassa was 30,000 km wide

Question 4

when did pangea start to break up

Answer 4

180-190 mya

Question 5

where did the breaking up of pangea originate

Answer 5

between NW africa and eastern seaboard of the USA

Question 6

how far has ireland drifted over last 200 mya

Answer 6

drifter 26º north and 17º west which is 3000 km

Question 7

what are the possible process that could have broken pangea

Answer 7

1. passive model –> slab pull
2. active model –> hotspot due to mantle plume that moved plates

Question 8

give evidence for continental drift

Answer 8

• continents look like jigsaw pieces that can fit together (africa and south america)
• mountain belts end abruptly but they match up in pangea (in central antartica/east australia, caledonian mountain belt is appalachians/east greenland/norway/scotland)
• fossils match on different continents
• bedrock geology matches
• glacial deposits make sense together

Question 9

how can palaeomagnetism of minerals help explain pangea

Answer 9

the paleomagnetism of minerals can be used to calculate the paleolatitude where the minerals were formed or deposited since the angle of inclination of the geomagnetic field changes with latitude from 0º at magnetic equator to 90º at magnetic pole.

Question 10

how can you calculate paleolatitude

Answer 10

tan I =2 tan λ
I = measured inclination of mineral magnetic field
λ = paleolatitude

Question 11

what are some possible errors in calculating paleolatitude

Answer 11

• strata could fold (can account for this with dip and strike and assume it was laid horizontally)
• original magnetism could have been destroyed and replaced by new magnetic orientation (with high heat flow or strong tectonic deformation)
• magnetic field can wander

Question 12

how did the himalayas form

Answer 12

when india and eurasia plates collided

Question 13

what is orogeny

Answer 13

when mountains are built due to continental crust buckling and thickening which form mountains at convergent plate margins

Question 14

what caused the alps to form and when

Answer 14

when africa and eurasian plate combined from 2.5-60 mya

Question 15

how did the pyrenees mountain belt form

Answer 15

iberian continental block rotates which opens the bay of biscay and closes the sea between france and spain which cause pyrenees