Chapter 2

Question 1

Tectonic

Answer 1

(tekton - “builder”) large scale processes affecting the structure of the Earth’s crust.

Question 2

Continental Drift

Answer 2

Large-scale movements of continents across Earth’s surface driven by the plate tectonic system. The gradual movement of the continents across the earth’s surface through geological time.

Question 3

Alfred Wegener 1915

Answer 3

Wrote a book on the break up and driftof continents, he laid out the similarity of geologic features on opposite sides of Atlantic. Pangaea - he named.

Question 4

Pangaea

Answer 4

Supercontinent that coalesced in the late Paleozoic era and comprised all present continents. It began to break up in the Mesozoic era.

Question 5

Seafloor Spreading

Answer 5

The mechanism by which new oceanic crust is formed at a spreading center on the crest of a mid-ocean ridge. as two plates move apart, magma wells up into the rift between them to form new crust, which spreads laterally away from the rift and is replaced continually by newer crust (convection).

Question 6

Plate tectonics

Answer 6

Theory that describes and explains the creation and destruction of Earth’s lithospheric plates and there movement over Earth’s surface.

Question 7

13 Major Plates

Answer 7

1 - Eurasian Plate
2 - North American Plate
3 - African Plate
4 - Indian Plate 
5 - Arabian Plate
6 - Philippine Plate
7 - Pacific Plate
8 - Cocos Plate
9 - Caribbean Plate
10 - Australian Plate
11 - Nazca Plate
12 - South American Plate
13 - Antarctic Plate

Question 8

Divergent Plate Boundary

Answer 8

Plates that move apart and new lithosphere is created (plate area increases - convection).

Question 9

Convergent Plate Boundary

Answer 9

Plates come together and one plate is recycled into the mantle (Plate area decreases). Collides into each other with one going under.

Question 10

Transform Faults

Answer 10

Plates slide horizontally past each other (plates do not change). Slide horizontally past each other and lithosphere is neither created nor destroyed.

Question 11

Continental Crust

Answer 11

1 - Continental Crust is not as easily recycled back into the mantle as oceanic crust
2 - Continental Crust is weaker. Plate boundaries that involve continental crust tend to be more spread out and more complicated than those involving oceanic crust.

Question 12

Mid-ocean Ridge

Answer 12

An under sea mountain chain at a divergent boundary, characterized by earthquakes, volcanism, and rifting. All caused by the tensional forces of mantle convection that are pulling the two plates apart.

Question 13

Continental Rifting

Answer 13

Is the belt or zone of the continental lithosphere where the extensional deformation (rifting) is occurring. These zones have important consequences and geological features, and if the rifting is successful, lead to the formation of new ocean basins.

Question 14

Subduction

Answer 14

A geological process that takes place at convergent boundaries of tectonic plates where one plate moves under another and is forced to sink due to gravity into the mantle. Regions where this process occurs are known as subduction zones

Question 15

Island Arc

Answer 15

Island arcs are long chains of active volcanoes with intense seismic activity found along convergent tectonic plate boundaries. Most island arcs originate on oceanic crust and have resulted from the descent of the lithosphere into the mantle along the subduction zone.

Question 16

Magnetic Anomaly

Answer 16

A pattern of long narrow bands of high or low magnetic intensity on the seafloor that are parallel to and almost symmetrical with respect to the crest of a mid-ocean ridge.

Question 17

Themoremanent Magnetization

Answer 17

When iron-rich lava cools, they become slightly but permanently magnetized in the direction of Earth’s magnetic field (of the time). The cold lava “remembers” the magnetization long after the magnetic field has changed.

Question 18

Magnetic Time Scale

Answer 18

The detailed history of Earth’s magnetic field reversals as determined by measuring the themoremanent magnetization of sample rocks whose are are known.

Question 19

Magnetic Chrons

Answer 19

(Greek: time) Major periods where the field is normal or reversed. Lasts about 1/2 a million years.

Question 20

Magnetic Subchrons

Answer 20

Short lived reversals of fields that last anytime from several thousand years to 200 000 years.

Question 21

Seafloor Spreading

Answer 21

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.
18 mm/year (North American plate and Eurasian Plate

Question 22

Relative Plate Velocity

Answer 22

The velocity at which one lithospheric plate moves relative to another.

Question 23

Global Positioning System - GPS

Answer 23

Earth-orbiting satellites are used to make the same type of measurements as geodesy. The satellite constellation serves as an outside frame of referance. The satellites emit high-frequency Radio waves keyed to precise atomic clocks on board. Geologists use GPS to measure plate movements on a regular basis.

Question 24

Isochron

Answer 24

A contour that connects rocks of equal age. Isochron tell us the time that has elapsed since the rocks were injected as magma into a spreading zone. Therefore the amount of spreading that has occurred since they formed.

Question 25

Development of the Continents

1.1 billion years ago

Answer 25

Rodinia formed

Question 26

Development of the Continents

750 million years

Answer 26

Late Proterozoic - Rodinia starts breaking up

Question 27

Development of the Continents

237 million years

Answer 27

Early Triassic - Pangea assembled, Thetis ocean, Panthanlassic Ocean

Question 28

Development of the Continents

195 million years

Answer 28

Early Jurassic - Pangea break up, Laurasia, Gondwana, Pacific Ocean

Question 29

Development of the Continents

150 million years

Answer 29

Late Jurassic - Australia, India, Antarctic - breaking off from Africa

Question 30

Development of the Continents

66 million years

Answer 30

Late Cretaceous - Atlantic ocean widens

Question 31

Mantle Convention

Answer 31

Theory of mantle convention provides an example of why plates move. Mantle convection is the “engine” that drive large scale tectonic processes operating on Earth’s surface.

Question 32

Whole Mantle Convention

Answer 32

The material from the plate circulates all the way through the mantle. Down as far as the core-mantle boundary.

Question 33

Stratified Convention

Answer 33

Mantle is divided into two layers: Plate recycling of the lithosphere is confined to the upper mantle. A lower mantle is the portion moves slower then the upper mantle. The separation is maintained because the upper system is lighter than the lower system.