Ch 4. Distribution of Oceans and Continents

Question 1

Who proposed the Continental Drift Theory ?

Answer 1

Alfred Wegener in 1912

Question 2

What is Continental Drift Theory ?

Answer 2

According to Wegener’s Continental Drift Hypothesis, all the landmasses were a solitary continental mass. This super continent was called Pangea and a super sea called Panthalassa encompased the landmass

Question 3

When did Pangea split ?

Answer 3

200 million years ago

Question 4

Pangea broke into ____ and ____

Answer 4

Laurasia and Gondwana

Question 5

Which sea partitioned Laurasia and Gondwana ?

Answer 5

Tethys sea

Question 6

What is Tillite ?

Answer 6

It is a sedimentary rock formed out of deposits of glaciers found in the Gondwana land system of sediments

Question 7

What forces are responsible for the continental drift (according to Wegener) ?

Answer 7

1. Pole fleeing force
2. Tidal force

Question 8

Thermal Convectional Current Hypothesis was given by ____ in the year ____

Answer 8

Arthur Holmes in the year 1928-1929

Question 9

What is Convectional Current Hypothesis ?

Answer 9

The driving force of the mountain building is thermal convection currents which occur due to excess heat in the substratum where disintegration of radioactive elements generates heat regularly

Question 10

What is a Continental Shelf ?

Answer 10

It is basically the streched margin of all the continents which is occupied by comparatively shallow gulfs and seas. It is the shallowest piece of ocean

Question 11

What is the average width of an ocean shelf ?

Answer 11

80 km

Question 12

The largest ocean shelf in the world is ?

Answer 12

Siberean shelf in the Arctic Ocean (480 km to 2,000 km (not imp.))

Question 13

What is the depth of continental slope ?

Answer 13

180 - 3600 meters

Question 14

What is Continental Rise ?

Answer 14

The base of the continental slope has some deposits of sediments. This belt of sediment is called Continental Rise

Question 15

What is a deep sea plain / Abyssal plain ?

Answer 15

The plain area lying in between the foot of a continental rise and a mid-ocean ridge. Flattest and the most featureless area in the ocean

Question 16

Depth of Abyssal plain is ?

Answer 16

3000 - 6000 meters

Question 17

What are Oozes ?

Answer 17

The sediments which are developed from the remains of the living organisms are known as Oozes

Question 18

How are Trenches or Oceanic Deeps formed ?

Answer 18

They are formed due to tectonic activities like ocean-ocean plates convergence or ocean-continent convergence

Question 19

What is the deepest trench in the world ?

Answer 19

Mariana Trench off Guam Islands in the Pacific Ocean is the deepest trench with a depth of more than 11 km

Question 20

What are Mid-Oceanic ridges ?

Answer 20

These are submerged mountain ranges, formed by plate tectonics. It is made of two chains of mountains separated by a large depression

Question 21

What is a seamount ?

Answer 21

A mountain having pointed peak, mounting from the seafloor and which usually do not reach the surface of the ocean. They are generally 3000 - 4000 meter tall

Question 22

Which is the largest Canyon on earth ?

Answer 22

Congo Canyon

Question 23

What is a Guyout / Table mount ?

Answer 23

A flat-topped seamount

Question 24

What is an Atoll ?

Answer 24

A ring shaped coral reef containing a coral rim which encompasses a lagoon completely or incompletely

Question 25

Who gave the theory of Sea Floor Spreading ?

Answer 25

Harry Hess in 1962

Question 26

What is Seafloor spreading ?

Answer 26

Seafloor spread is a process that occurs at mid-ocean ridges, where new oceanic crust is formed through volcanic activity and then gradually moves away from the ridge.

Question 27

In the Trenches where subduction occurs, the value of the gravitational constant ‘g’ is more. True or false ?

Answer 27

False

Question 28

Who gave Plate Tectonic Theory ?

Answer 28

McKenzy and Parker in 1967

Question 29

What is Plate Tectonic Theory ?

Answer 29

Theory that considers the Earth’s lithosphere to comprise a number of large tectonic plates which have been slowly moving since about 3.4 billion years .

Question 30

Which tectonic plate is moving fast ?

Answer 30

East Pacific Rise in the region of South Pacific (around 3400 km west of Chile) has the fastest rate (more than 15cm per year)

Question 31

Which tectonic plate is moving slower ?

Answer 31

Arctic Ridge has the slowest rate (less than 2.5 cm / year)

Question 32

What are the major tectonic plates ?

Answer 32

1. Antarctica and the surrounding Oceanic plate
2. North American plate
3. South American plate
4. Pacific plate
5. India-Australia-New Zealand plate
6. Africa with the eastern Atlantic floor plate
7. Eurasia and the adjacent oceanic plate

Question 33

What are different types of plate boundaries ?

Answer 33

1. Divergent plate boundary
2. Convergent plate boundary
3. Transform / Transcurrent fault boundary

Question 34

What is a Transcurrent Edge / Conservative Edge / Transform Fault ?

Answer 34

Two plates grind against each other but there is no creation nor destruction of landform but just deformation of the existing landform. These faults are generally perpendicular to the mid-oceanic ridges

Question 35

Which minerals (economically important) are found closer to the boundary of tectonic plates ?

Answer 35

Copper and Uranium

Question 36

What is the Pacific ring of fire ?

Answer 36

The Ring of Fire is a region around much of the rim of the Pacific Ocean where many volcanic eruptions and earthquakes occur. It is 40,000 km long and up to about 500 km wide.