Geography

THEORY OF PLATE TECTONICS AND CONTINENTAL DRIFT

THEORY OF PLATE TECTONICS AND CONTINENTAL DRIFT

  1. Eurasia and North Amcrica are the remnants of_______________ .

(a) Laurasia                          (b)   Gondwanaland            (c) Pangaea

The name combines the names of Laurentia, the name given to the North American craton, and Eurasia.

  1. Pangaea was divided into Gondwanaland and Laurasia in_______________ .

(a) Mcsozoic Era                 (b) Palaeozoic                  (c)                                                               Cenozoic

Pangaea was a patchwork supcrcontinent formed in the Late Palaeozoic and continued into the early part of the Mesozoic. The part of Pangaea that lies in the Northern Hemisphere is called Laurasia. It includes most of the present-day North America, Greenland, Europe, and Asia. Gondwana is the part of Pangaea that lies in the Southern Hemisphere. It includes most of the present-day South America, Africa, India, Australia, and Antarctica.

  1. _______ proposed that the moon was torn from the earth in the pacific Basin.

(a) Wegner                           (b) Franklin                      (c)                                                            F.D. Taylor

  1. The word ’lithospheric plates’ denotes their___________ .

(a) Mobile character            (b) Rigidity                       (c)                                                                 Activity

Lithospheric plates are another name for the pieces of die Earth’s fractured crust. These pieces

are better known as the tectonic plates. As a whole the lithosphere is the outermost part of the Earth. It comprises the crust and the upper part of the mantle which is an elastic solid. The theory for plate tectonics states that the lithosphere is like a rigid raft that floats on top of the • lower parts of the mantle.

  1. The number of major and minor plates is____________

(a)    7, 14                         (b)   7, 10                           (c)                                                          1,11    (d) None of these

  1. The theory of, continental drift’ was presented by Alfred Wegener in_______________ .

(a)    1901                         (b)   1815                           (c)                                                         1915    (d) 1801

In 1915, the German geologist and meteorologist Alfred Wegener first proposed that parts of the Earth’s crust slowly drift atop a liquid corc. The fossil record supports and gives credencc to the theories of continental drift and plate tectonics.

7-      _______ in 1939 proposed that movement of land mass is due to heat-sustained convection

cells.

(a) A-Ortelius                                                            (b) Benjamin Franklin

(c) Arthur Holmes                                                     (d) Taylor

  1. Tectonic process takes place at_____________ .

(a)    Plate boundaries (b)          Lithosphere                (c)                                       Mountain ranges    (d) None of these

  1. The largest of all plates is__________

(a) Eurasian                       (b) Pacific                          (c)         North American

The Pacific Plate is the largest cruslal plate on our planet. The plate is presently shrinking as the Atlantic Ocean increases in size pushing the North American Plate slowly westward. This movement has created subduction zones that cause volcanoes to erupt, large subduction zone earthquakes and tsunamis.

  1. North American plate meets________ along California’s San Andreas Fault.

(a)    Nazca Plate               (b)   Pacific  Plate               (c)                                         Caribbean Plate    (d) None of these

 

  1. The African plate extends eastward from the mid-Antarctic ridge between__________________ .

(a) 45N-55S                       (b) 35N-35S                      (c) 45N-65S                     (d) None of these

  1. The Indo-Australian plate meets the pacific plate in______________ .

(a) New Zealand                 (b) East Timor                   (c) New Guinea                (d) None of these

Australia, which sits at the leading edge of the giant Indo-Australian Plate, moves in a north­easterly direction. In so doing, it collides with the western edge of the Philippine Plate. This collision pushes up the ocean floor above sea level, creating island chains, island arcs and a twisted, tumultuous sea floor.

The Pacific Plate, moving northwest, subducts under the eastern edge of the Philippine Plate. This area of subduction is a holbed of volcanic and earthquake activity and part of the infamous “Ring of Fire”.

  1. Australian-Indian Plate meets the Eurasian plate at_______________ .

(a) Himalayas                       (b) Andes                        (c)  Zagros

The Indo-Australian Plate meets the Eurasian Plate and the type of boundary created is a convergent boundary. The collision between the two plates has created the Himalayan Mountains due to this convergence.

  1. ______ is wedged between South Pacific Plate to the east and South American Plate to the

west.

(a) Caribbean Plate               (b) Nazca Plate                (c)  Scotia Plate               (d)   Gorda Plate

The South American Plate is in motion, moving westward from the Mid-Atlantic Ridge. The eastward-moving and denser Nazca Plate is subducting under the western edge of the South American PLie along the Pacific coast of the continent at a rate of 77 mm per year. This collision of plato is responsible for lifting the massive Andes Mountains and causing the volcanoes which are strewn throughout them.

  1. Cocos and Uivcra, both are______________ .

(a) Continental crust                                                    (b)  Oceanic crust nlates

(c) Mountain ranges

Oceanic crust is the part of Earth’s lithosphere that surfaces in the ocean basins. Oceanic crust is primarily composed of mafic rocks, or sima, which is rich in iron and magnesium. It is thinner than continental crust, or sial, generally less than 10 kilometres thick; however it is denser, having a mean density of about 3.3 grams per cubic centimetre.

  1. Scotia Plate is present at the    end of South America.

(a) Northern                          (b) Southern                    (c)  Eastern                     (d)   Western

  1. The tiny_________ Plate will eventually disappear by subduction beneath American Plate.

(a) Juan dc Fuca                 (b) Nazca                                                       (c) Scotia

The zone which separates the Juan de Fuca Plate and the North American Plate has a very large fault area which can produce large earthquakes with a magnitude of 9.0 or greater if a rupture were to occur. It is where the Juan de Fuca Plate is subducting beneath the North American Plate.

  1. Sea floor spreading results from___________ .

(a) Divergence                    (b) Convergence                     (c) Lateral displacement

A divergent plate movement occurs when two plates move away from each oilier. Magma from the mantle underneath the crust rises up to the surfacc cools and solidifies. This divergent

boundary is considered constructive since new crust is formed. This process is also callcd sea- floor spreading.

  1. When due (o tensionnl forces sialic crust is pulled apart,_____________________ is formed.

(a) Ridge                             (b) Rift valley                    (c) Volcano — ~                     (d) Mountain

  1. A major system of rift valleys occurs in______________ .

(a) North America              (b) Eastern Europe             (c) Eastern Africa                    (d) Australia

The East African Rift System (EARS) is one of the geologic wonders of the world, a place where the Earth’s tectonic forces arc presently trying to crcate new plates by splitting apart old ones. In simple terms, a rift can be thought of as a fracture in the Earth’s surfacc that widens over time, or more technically, as an elongate basin bounded by opposed steeply dipping normal faults.

  1. The movement of denser plate towards the interior of Earth during collision is

callcd________ .

(a) Subduction                    (b) Convergence (c) Transform

  1. The subduction zone is a place of___________ tectonic activity.

(a) Intense                          (b)  Less                             (c)    Slight

  1. The process of subduction produces a__________________________________________________ in

(a) Trench                           (b)  Valley                          (c)      Fold

Subduction is a result of a collision between two tcctonic plates, either oceanic to oceanic collision or oceanic to continental plate collision. The heavier or denser plate sinks under the more buoyant less dense plate, and is drawn down into the upper mantle.

  1. ________ are also known as destructive boundaries.

(a) Convergent plates                                                (b)  Divergent plates

(c) Lateral movement zones

  1. Oceanic-Oceanic plate convergence creates___________

(a) Archipelago                   (b)  Ridge                           (c)       Rift

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