MODULE 6 - Seafloor Spreading

Question 1

What supports the theory of seafloor spreading?

Answer 1

magnetic reversal

Question 2

Why were magnetic patterns found on the ocean floor puzzling?

Answer 2

They showed alternating bands of normal and reversed polarity.

Question 3

How did scientist discover that rocks farther away from the mid-ocean ridge
were older than those near it?

Answer 3

by determining the age of rock samples obtained by drilling on the sea floor

Question 4

What does scientist thought about the seafloor before they had data from echo sounders?

Answer 4

The seafloor is completely flat.

Question 5

What features of seafloor mountain ranges on the ocean floor upwells
magma and formed new ocean floor?

Answer 5

mid-ocean ridge

Question 6

What technology did scientist used in mid-1900 to map the mid-ocean ridge?

Answer 6

sonar

Question 7

What features of seafloor is described as the deepest areas of the ocean
where subduction takes place

Answer 7

Trench

Question 8

What indicators where observed by geologist to conclude that the polarity is reversed?

Answer 8

the north and south are at the center

Question 9

scientist from the 1960s is credited for proposing the theory of seafloor spreading?

Answer 9

Harry Hess

Question 10

What earth internal process drives seafloor spreading?

Answer 10

convection

Question 11

Where can we usually found the shrimps, crabs and other organisms
cluster near hot water vents in the ocean floor?

Answer 11

deep-ocean floor

Question 12

What comprises the Mid-Ocean ridges?

Answer 12

mountains

Question 13

Where are you expected to find the oldest rock on the ocean floor?

Answer 13

further away from the ridge

Question 14

How did drilling samples show that sea-floor spreading really has taken
place?

Answer 14

The further away from the ridge the samples were taken, the older the
rocks were, the younger rocks were always in the center of the ridges.

Question 15

In seafloor spreading, in what parts does molten material
rises from the mantle and erupts or flows out?

Answer 15

Along mid-ocean ridges

Question 16

Mr. Alvarez wants to make a research about the magnetic property of the sea
floor. One day he joined his friend in making a research. He noticed that he
used a device that detect magnetic field. What do you call that instrument?

Answer 16

magnetometer

Question 17

How will you compare the age of the rocks in the seafloor?

Answer 17

the younger rocks are in the middle at the ridge, the older are far from
the ridg

Question 18

What are the evidences that support the theory of seafloor spreading?

Answer 18

Molten materials, magnetic strips, drilling sample

Question 19

What feature of seafloor is shallow, gradually sloping seabed around the edge
of a continent and has a depth less than 200 meters and can be thought of as
the submerge edge of a continent

Answer 19

Mid- ocean ridge

Question 20

What device uses sound waves off underwater objects and then record the
echoes of these sound waves

Answer 20

sonar

Question 21

How was new oceanic crust formed?

Answer 21

when molten material cools and forms strip of solid rocks in the center
of the ridge.

Question 22

Before the invention of sonar device, what was the belief of many people about
the ocean floor?

Answer 22

a flat surface

Question 23

Who proposed that seafloor is spreading?

Answer 23

Harry Hess

Question 24

What causes seafloor spreading?

Answer 24

Magma and convection

Question 25

What is the age of the oldest seafloor?

Answer 25

180 million years