Magnetic Stripes

Question 1

Earth’s magnetic field

Answer 1

invisible lines of force that extend from one magnetic pole to the other

Question 2

Do the magnetic poles align with the geographic poles perfectly?

Answer 2

no

Question 3

How do compass needles work?

Answer 3

get aligned with magnetic line of force and points to the magnetic poles/magnetic north

Question 4

How do we know that we have a magnetic field?

Answer 4

can use it for navigation and some minerals are magnetitic

Question 5

Definition of paleomagnetism

Answer 5

rocks record the strength and direction Earth’s magnetic field at the time the rocks formed

Question 6

Example of the process of paleomagnetism using what type of rocks

Answer 6

iron-rich, volcanic, basalt, magnetite

Question 7

Magnetic reversal

Answer 7

Earth’s magnetic field periodically reverses polarity, magnetic north poles will become south pole, vice versa

Question 8

What do these rocks need to cool below for this process to begin, explain it pls

rocks in lava, once below, what happens?

Answer 8

Nonmagnetic in molten lava, but once below Curie point (585C for magnetite), iron grains become magnetized and align themselves in the direction of the present magnetic lines of force

Question 9

Normal polarity

Answer 9

rocks with the same magnetism as the present magnetic field

Question 10

reverse polarity

Answer 10

rocks with the opposite magnetism as the present magnetic field

Question 11

What was used to create a magnetic time scale and what was used to create magnetic surveys?

Answer 11

radiometric dating
magnetometers

Question 12

what were magnetometers originally used for and when?

Answer 12

to look for submarines
WW2

Question 13

Why were oceanographers conducting magnetic surveys?

Answer 13

to make maps of seafloor topography and see variations in the strength of magn.field

Question 14

What did Vine and Matthews discover?

Answer 14

high and low intensity strips supported seafloor spreading

Question 15

High intensity stripes vs low intensity stripes (anomaly and polarity)

Answer 15

high intensity=positive anomaly and normal polarity

low intensity=negative anomaly and reverse polarity

Question 16

What do the high and low intensity stripes do to Earth’s magnetic field?

Answer 16

high intensity: strengthen
low intensity: weakens

Question 17

how are the stripes forming this symmetrical pattern?

Answer 17

magma solidifies and is magnetized with the present polarity, seafloor spreading causes it to widen, but reverse polarity seafloor will form in the middle of old strip (normal polarity), causing the same strip to be pulled in opp.directions

Question 18

What was the drilling ship called of the Deep Sea Drilling Project?

Answer 18

Glomar Challenger

Question 19

How did researchers on the Challenger date seafloor?

Answer 19

fossil remains of microorganisms in the sediment

Question 20

Where are the youngest ocean floor found? oldest?

Answer 20

near ridge crest
far from ridge crest, near continents

Question 21

what’s the age of the ocean floor?

Answer 21

180 million yrs old

Question 22

How did the Hawaiian island chain form?

Answer 22

mantle plume rises, pressure drops, and partial melting occurs (hot spot.) As the Pacific plate moves over it, a hot-spot tack is built

Question 23

Old Hawaiian island have ___ volcanoes? New?

Answer 23

inactive
active