Lecture #8 [Tectonics-Volcanoes]

Question 1

what are the four layers of the earth

Answer 1

CRUST
MANTLE
OUTER CORE
INNER CORE

Question 2

The core (s)

Answer 2

outer core is molten (liquid) extends to roughly 5000 km deep

inner core is solid and dense with a radius of 1450 km

Question 3

The Mantle and its three layers

Answer 3

Extends to ~3000km deep
lithosphere= upper mantle and crust it’s thin hard and rigid.
asthenosphere= rocks are so hot that they deform easy
mesosphere= rocks are rigid again

Question 4

The Crust [and it’s three rock types]

Answer 4

Mixture of rock types, beneath the oceans is 8km thich and beneath the continents is 30 km thick

igneous, sedimentary and metamorphic

Question 5

igneous rocks

Answer 5

formed by cooling and solidifying of magma
extrusive rocks (volcanic) spewed onto surface while still molten, undergo rapid solidification and cooling
intrusive rock (plutonic) cools and solidifies below the surface [i.e granite]

Question 6

Sedimentary rocks

Answer 6

Mechanical and physical weathering= rocks disintegrate
sediment is carried away by rivers and deposited
layers of deposits creates pressure on sediment and chemical cementation binds them

Question 7

Metamorphic Rocks

Answer 7

orginate as igneous or sedimentary
changes by heat and or pressure
changes structure, composirion, texture and appearance

Question 8

alfred wegner came up with which theory in the 20s and how was it supported

Answer 8

pangea super continent, africa and south africa fit like jigsaw but had no mechanis to explain how continental drift could operate

Question 9

Seafloor spreading theory

Answer 9

Harry hess in the 60’s

mid oceanic risged are where new crust is formed, magma rises from mantle, ocean floor spreads laterally
so cracks open spews out and makes new seafloor

Question 10

evidence for seafloor spreading

Answer 10

paleomagetism
iron rock is magnetized, becomes oriented toward the magnetic north and the field as reveresed close to 200 times, this explaines the alternating orientation of the ridges on the seafloor

core sampling
analyzing sea bottom sediments which thickness and age increased with increasing distance from oceanic ridges

Question 11

Divergent boundaries

Answer 11

move away from each other, continuous line of active volcanoes, mid-ocean ridges
“constructive”

Question 12

Convergent boundaries

Answer 12

plates moving in opposite directions collide
"destructive"
there are three types 
1) oceanic continental
2)oceanic oceanic
3)continental continental

Question 13

Transform boundaries

Answer 13

two plates slide past each other, transform faults

“conservative” earth quakes happen along fault

Question 14

Hotspots (mantle plumes)

Answer 14

stationary spots of volcanic activity
plates move over them volcanoes form
as plates move on volcanoes become inactive

Question 15

what are the 4 volcanic landforms

Answer 15

lava flows
volcanic peaks
calderas
volcanic necks

Question 16

Lava flows

Answer 16

lava spreads outward and cools

solidy in horizontal orientation

resembles stratified sedimentary rock

Question 17

Volcanic Peaks

Answer 17

volcanoes= surface expressions of subsurface igneous activity

Question 18

what are the four types of cones (volcanic peaks)

Answer 18

sheild volcanoes
composite volcanoes
lava domes
cinder cones

Question 19

sheild volcanoes

Answer 19

basaltic magma, quiet eruptions, broad and gently sloping [hawaiin islands]

Question 20

composite volcanoes

Answer 20

magma mixed chemistry, explosive or quiet eruptions
large, steep and symmetrical
[mnt st helens or baker]

Question 21

Lava domes

Answer 21

magma high in silica, explosive eruptions

usually small and irregularily shaped

Question 22

cinder cones

Answer 22

basaltic magma, pyroclastics small and steep

Question 23

Calderas

Answer 23

produced when volcano explodes and collapses. a depression with a huge diameter

Question 24

Volcanic neck

Answer 24

small, sharp spire. throat of an old volcano filled with solidified lave after last eruption