CGC1W Unit 2: Physical Processes Shaping Canada's Landscape

Flashcards covering Earth's internal structure, mantle convection currents, plate boundaries, the rock cycle, Canadian landform regions, and the Cascadia Subduction Zone.

What is the difference between a natural hazard and a natural disaster?

A natural hazard is the threat of a naturally occurring event which could cause negative impacts (e.g., earthquake, flood, hail, hurricane). A natural disaster is when there are negative impacts to communities that are caused by a natural hazard.

What are the physical and chemical characteristics of Earth's inner core?

Solid, extremely hot, dense, high pressure, mostly iron.

What are the physical and chemical characteristics of Earth's outer core?

Liquid, hot, high pressure, mostly iron/nickel.

What are the physical characteristics and role of Earth's mantle?

Liquid rock (semi-solid/plastic), where convection currents circulate.

What is the asthenosphere?

The uppermost 'soft plastic'-like mantle, which the lithosphere moves on.

What is the lithosphere?

'Rocky crust' - thin, made up of rock, including continental and oceanic crust.

How do continental crust and oceanic crust compare in thickness and density?

Continental crust is thick and less dense, while oceanic crust is thin and more dense.

What happens to temperature, pressure, and density as depth increases towards the center of the Earth ($6400\,\text{km}$)?

Temperature, pressure, and density all increase towards the center of the Earth.

How are convection currents formed in Earth's mantle?

They are formed when liquid rock of the mantle is heated by the centre (core) of the Earth. As liquid rock warms, it becomes less dense and rises towards the upper mantle/asthenosphere. As it rises away from the core it cools down, becomes more dense, and falls back towards the core where it is heated again.

Why are convection currents significant to tectonic hazards?

Rising warm mantle rock exerts force on the crust (lithosphere), moving tectonic plates. Because convection currents drive tectonic plate movement, they are responsible for natural hazards like earthquakes, volcanoes, and tsunamis; without them, these hazards would not exist.

What features and natural hazards occur at a continental-continental convergent plate boundary?

Plate collision zones, subduction zones, faulted and folded mountain systems, and earthquakes.

What features and natural hazards occur at a continental-oceanic convergent plate boundary?

Ocean trenches (where sediments accumulate, fold, and/or metamorphose), subduction zones, earthquake zones, rising magma, volcanic mountain ranges, and hazards including earthquakes, tsunamis, and volcanoes.

What features and natural hazards occur at a divergent plate boundary?

Spreading centres, mid-ocean ridges, rising magma driven apart by convection currents, and hazards including earthquakes and volcanoes.

What natural hazard is primarily associated with a transform plate boundary?

Earthquakes caused by tectonic plates sliding past each other.

In the provided rock cycle diagram, what do the labels A, B, C, and D represent?

A represents igneous rock, B represents weathering, erosion, and deposition, C represents sedimentary rock, and D represents metamorphic rock.

What economically significant natural resource minerals are associated with igneous rock?

Diamonds (granite, aluminum, copper, tin, and nickel are also associated).

What economically significant natural resources are associated with sedimentary rock?

Oil and coal (natural gas, bitumen, salt, chalk, limestone, and potash are also associated).

What economically significant natural resources are associated with metamorphic rock?

Marble (graphite for pencils, gemstones like ruby/jade/sapphire, and metallic minerals like gold, silver, copper, and nickel are also associated).

In which geological era was the Canadian Shield formed?

Precambrian era ($4.6\,\text{billion years ago} - 541\,\text{million years ago}$).

In which geological eras were the Appalachian mountains formed?

Paleozoic ($541\,\text{myrs} - 252\,\text{myrs}$) to Mesozoic ($252\,\text{myrs} - 66\,\text{myrs ago}$).

In which geological era was the Western Cordillera formed?

Early Cenozoic era ($66\,\text{myrs ago} - \text{present day}$).

In which geological eras were the Interior Plains formed?

Mesozoic (tropical plants and dinosaurs) to late Cenozoic (glaciation).

In which geological era were the Great Lakes-St. Lawrence Lowlands formed?

Most recently formed from glaciation closer to present day Cenozoic.

According to the cross-section diagram of Canada, what five landform regions appear from west to east?

From west to east: Western Cordillera, Interior Plains, Canadian Shield, GLSL (Great Lakes-St. Lawrence Lowlands), and Appalachians.

How was the Western Cordillera formed?

The North American (continental) plate moved north/west and collided with the Pacific (oceanic) plate, pushing sedimentary rock (formed from the continuous weathering of the Canadian Shield) upward to create the Rocky Mountains.

How did oil and shale form within the Western Cordillera?

Former organic material from a previous tropical rainforest to the west of the Canadian Shield that died off during the mass extinction at the start of the Cenozoic period was compressed within the sedimentary rock as the mountains formed.

What natural hazards occur in the Western Cordillera and what causes them?

Earthquakes, tsunamis, and volcanoes occur due to the collision between tectonic plates. In addition, sharp peaks of sedimentary rock can cause rock slides, and snow accumulation can lead to avalanches.

What is the Cascadia Subduction Zone?

An ocean-continent plate boundary located off the northwest coast of North America, where the Pacific Plate is subducting under the North American plate; it is considered one of the top natural hazard risks on Earth.

What is the spatial significance of the location of the Cascadia Subduction Zone?

It is located just off the coast of British Columbia's lower (southwest) mainland and Vancouver Island, which contains the largest density of population in the province.

What magnitude and frequency of earthquakes characterize the Cascadia Subduction Zone?

Massive 'megathrust earthquakes' occur approximately every $500\,\text{yrs}$ or so (the last one occurred in $1700$), which can generate tsunamis and are commonly referred to as 'the big one'.

What is the scope of impact of a potential megathrust earthquake along the Cascadia Subduction Zone?

It could devastate communities along BC's coast and within its interior, causing loss of life and property damage estimated in the billions of dollars, as well as reshaping the coastal landscape.

What is the value of understanding the Cascadia Subduction Zone hazard risk?

Understanding the risk helps people mitigate widespread disaster by taking protective measures to reduce vulnerability (such as reinforcing infrastructure) and investing in public education and first responder training to increase coping capacity.