Plate Tectonics

Question 1

Geologic Cycle

Answer 1

Geology, topography and climate influence the type, location, and intensity of earth processes.

Materials at or near Earth’s surface have been continuously created and modified by various physical, chemical. and biological processes: these processes constitute the geologic cycle.

The geologic cycle consists of a group of sub-cycles: the tectonic cycle; the rock cycle; the hydrologic cycle; and biogeochemical cycles.

Question 2

Tectonic Cycle

Answer 2

Tectonic activity refers to large-scale earth processes that cause the movement and deformation of Earth’s lithospheric plates.

These processes create landforms and landscapes at a variety of spatial scales (e.g., orogenic mountain ranges and ocean basins to individual faults.)

Question 3

Endogenic Processes

Answer 3

Tectonic process are driven by energy generated deep within Earth: original heat of formation of the planet, heat generated by crystallization of the core, and heat supplied by radioactive decay of elements in the mantle.

Question 4

Rock Cycle

Answer 4

Rocks are aggregates of one or more minerals.

Minerals are naturally occurring crystalline materials with specific chemical compositions and a narrow range of physical properties.

Links to endogenic processes and exogenic processes driven by energy from the sun.

Question 5

Three Classes of Rock Are

Answer 5

Igneous
Sedimentary
Metamorphic

Question 6

Internal Structure of The Earth

Answer 6

Internal structure based upon: chemical composition of rock; physical state - solid vs. liquid; density; and rock strength.

Solid inner core, liquid outer core, and solid mantle.

Question 7

Inner Consists Of

Answer 7

> 1300 km thick

Extremely hot temperatures

primarily metallic; consists mostly of iron (Fe) with minor amounts of nickel (Ni), sulphur (S), and oxygen (O)

Question 8

Liquid Outer Core Consists Of

Answer 8

Over 2000km thick

Composition close to the inner core.

Movement within the outer core generates Earth’s magnetic field.

Question 9

Solid Mantle

Answer 9

~3000km thick

Composed largely of iron (Fe) and magnesium (Mg) - rich silicate minerals - ferromagnesian minerals.

Question 10

What is the lithosphere?

Answer 10

Cool, strong outermost layer of Earth

Crust + Rigid uppermost portion of mantle

Varies in thickness: few km beneath mid-oceanic ridges

Question 11

Asthenosphere

Answer 11

Lithosphere overlies asthenosphere, a mass of hot, relatively weak rocks (magma) capable of slow movement.

convection operates to move material within the mantle; convection is driven by heat from Earth’s core

Question 12

Plate Tectonics

Answer 12

Lithosphere is broken into larger and smaller pieces call lithospheric plates.

Plates may include a continent and parts of ocean basins, or may be restricted to only ocean basins.

Plates move relative to one another at rates of several cm per year.

Processes involved in the creation, movement, deformation and destruction of plates are collectively known as plate tectonics.

Question 13

Continental Drift Theory

Answer 13

developed by Alfred Wegener in 1912.

Coastline fit - Southern Hemisphere continents

Similarities in Paleozoic geology and palaeontology

Single Continental Landmass - Gondwanaland

Theory lacked a convincing mechanism capable of moving continents

Question 14

Who discovered the seafloor spreading and subduction?

Answer 14

American Harry Hess and Japanese Kiyoo Wadati and American Hugo Benioff in the 1950’s and 1960’s

Question 15

Mid Oceanic Ridges are associated with what natural disasters?

Answer 15

Spatial patterns of earthquakes and volcanism

Question 16

Oceanic Trenches are associated with what natural disasters?

Answer 16

Spatial pattern of earthquakes in Wadati-Benioff zone and Volcanism along continental margins.

Question 17

Plausible mechanism for continental drift?

Answer 17

Seafloor spreading

Question 18

Geomorphology

Answer 18

refers to the study of the morphology of the surface of the Earth and the processes operating on it, in the present, past, and the future

The morphology of the Earth’s surface is created by the constant interaction of endogenic processes, those processes that create topographic relief, and exogenic processes, those processes that reduce topographic relief.

Physical/ Environmental Controls to Earth Processes to Landforms to Landscapes.

Question 19

Geomorphology seeks to

Answer 19

understand the sequence of landscape development

understand the dynamics of physical, chemical, and biological processes that create landforms

predict the nature of future change based on field observations, physical experiments, and numerical modelling

Question 20

Structure

Answer 20

Bedrock structure influences physiography

Question 21

Tectonic Geomorphology

Answer 21

Structural geology, geophysics, geodesy

Question 22

History

Answer 22

Sequence of landscape development

Question 23

Historical Geomorphology

Answer 23

Stratigraphy, palaeontology, archaeology, pedology.

Question 24

Processes

Answer 24

Endogenic vs. Endogenic processes that affect landforms (driving forces)

Question 25

Process Geomorphology

Answer 25

Geography, Sedimentology, Engineering

Question 26

Earth Materials

Answer 26

Strength and resistance of rocks and sediments (resisting forces) - geology engineering

Question 27

Tension

Answer 27

Lithospheric plates are pulled apart - divergent plate boundaries.

Question 28

Compression

Answer 28

lithospheric plates are pushed together - convergent plate boundaries

Question 29

Lateral Movement

Answer 29

Lithospheric plates move horizontally past each other - transform plate boundaries

Question 30

Landscapes of Tension

Answer 30

Landscapes marked by tension, crustal extension, and the failure of brittle rock units are dominated by normal faulting. These processes occur at mid-oceanic ridges (spreading centres) and contribute to seafloor spreading.

Question 31

Normal Fault

Answer 31

Rocks fail along a steeply inclined surface, typically sloping at the angle of between 45 degrees and 70 degrees.

Question 32

Rift Valley

Answer 32

When two normal faults sloping in opposite directions create a rift valley that flanks a structural depression termed a graben.

Question 33

How do mid-oceanic ridges form?

Answer 33

Where magma from the mantle rises and is erupted as pillow lavas forming broad ridges with a central rift valley where plates break apart and move apart.

Question 34

New formed oceanic lithosphere composed of?

Answer 34

Basalt and Gabbro, moves away from the ridge crest.

Question 35

Convergent Plate Boundaries (3 types)

Answer 35

Oceanic - Continent Collision Oceanic - Oceanic Collision Continent - Continental collision

Question 36

What are the results of compression?

Answer 36

shortening of the lithosphere, a combination of folding and faulting, resulting in an increase in elevation and thickening of the lithosphere – creates orogenic mountain chains

Question 37

What does compression do offshore?

Answer 37

offshore, subduction of oceanic lithosphere creates deep, narrow depression in the seafloor – an oceanic trench

Question 38

Cuesta

Answer 38

ridge composed of sedimentary bedrock, where one side dips at a gentle angle and the opposite side forms a steep escarpment.

Question 39

Features in landscapes marked by compression include:

Answer 39

Rock units include folding and reverse (thrust) faulting

Question 40

Folded terrains are caused by

Answer 40

alternating of down-warped synclines and up-warped anticlines - often leading to the development of ridges (anticlines) and valleys (synclines)

Question 41

Cuesta

Answer 41

Ridge composed of sedimentary bedrock, where on slide dips at gentle angle and the opposite side forms a steep escarpment

Question 42

Reverse Faults

Answer 42

Move rocks on the upper side of the fault (called the hanging wall) up and over those on the underside of the fault (the footwall)

Question 43

Thrust Faults

Answer 43

most common class of reverse faults, involving movement over gently inclined surfaces. thrust-faulting is characteristic of compressive terrain associated with subduction zones.

Question 44

How are rock units split?

Answer 44

Horizontally by transform (or strike-slip) faults and displaced laterally. A clean break results in no difference between the two blocks. More commonly, the moving blocks are forced into contact, fracturing rock faces and grinding the contact surface under high pressure.

Question 45

Transform Faults

Answer 45

are most common on the ocean, but some occur on continents; e.g., San Andreas Fault in California, Queen Charlotte Fault west of Haida Gwaii

Question 46

Canadian Shield

Answer 46

Created between 1.96 and 1.81 billion years ago through the collision and welding together of at least six ancient microcontinents. Divided in structural provinces consisting largely of Archean granite (igneous) and gneiss (metamorphic) rocks, welded together by orogenic mountain belts consisting largely of Late Proterozoic volcanic and metamorphosed sedimentary rocks. Landform comprising the exposed part of the North American craton.

Question 47

Craton

Answer 47

Refers to old continental crust preserved deep within the centers of continents.

Question 48

North American-craton

Answer 48

Large continent-sized block of Archean and Proterozoic rock stretching from Mexico to USA, Canada, and Greenland

Question 49

Canadian Shield | Physiographic Region Characterized by:

Answer 49

Rolling topography (local relief between 60-90 metres) Product of weathering and erosion over long periods of geological time. (i.e., 100's million years) Present topography influenced by Pleistocene glacial erosion; a lake-studded landscape.

Question 50

Appalachian Mountains

Answer 50

Rock range in age from the Precambrian to the Mesozoic mountain building was associated with the opening and closing of the Iapetus Ocean

Question 51

Appalachian Mountains | Closure of the Iapetus Ocean was associated with...

Answer 51

Subduction of oceanic lithosphere and extensive volcanism; an ocean-continent collision

Question 52

Appalachian Mountains | Closure was terminated by

Answer 52

A Continent to continent collision accompanied by folding, thrusting, and metamorphism of sedimentary rocks along the continental margin.

Question 53

Appalachian Mountains In the early Mesozoic _______ along the eastern border of this mountain system was associated with the creation of the Atlantic Ocean Basin

Answer 53

Continental Rifting

Question 54

Canadian Cordillera

Answer 54

this region includes the mountains of British Columbia, Alberta, Yukon, and Northwest Territories these mountain ranges have resulted from plate collision and crustal shortening the eruption of basaltic lavas, the construction of composite volcanoes, the intrusion of granite batholiths, and the folding and overthrusting of continental lithosphere have accompanied ocean-continent collision during the Mesozoic and Cenozoic

Question 55

Innuitian Mountains

Answer 55

this region of Canada experienced rapid deposition of sedimentary rocks and continuous subsidence throughout the early Paleozoic (Cambrian-Devonian) orogeny in the Late Paleozoic (Devonian-Carboniferous) involved the eruption of basaltic lava and the folding and faulting of the overlying sedimentary rocks further uplift of the region was associated with the emplacement of granite batholiths (epeirogeny) subsequent weathering and erosion (Carboniferous-Cretaceous) heralded the return to rapid sedimentation and subsidence orogeny in the Early Paleogene involved the uplift, folding and faulting of the sedimentary rocks and the intrusion of igneous dykes. 

Question 56

Plate Tectonics and Hazards

Answer 56

earthquakes and volcanic eruptions threaten human populations living near lithospheric plate boundaries tsunamis are generated by subduction-zone earthquakes landslides and snow avalanches occur most commonly in mountains produced by lithospheric plate collisions