Earth Structure and Geological Time Scale

• The Earth's structure consists of several layers: the inner core, outer core, mantle, and crust
• The inner core is a solid sphere made mostly of iron and nickel
• The outer core is a liquid layer, also composed of iron and nickel
• The mantle is a mostly-solid, thick layer composed of silicate rocks
• The crust is the outermost solid layer, divided into oceanic and continental crust

Geological Time Scale: Eras

• The geological time scale divides Earth's history into eons, eras, periods, epochs, and ages
• The four major eras are: Precambrian, Paleozoic, Mesozoic, and Cenozoic
• The Precambrian Era represents the earliest part of Earth's history, characterized by the formation of the Earth and the emergence of early life forms like bacteria and algae
• The Paleozoic Era saw the diversification of marine life, the development of land plants and animals, and the formation of large coal deposits
• The Mesozoic Era is known as the "Age of Reptiles," with the dominance of dinosaurs; it ended with a mass extinction event
• The Cenozoic Era is the current era, marked by the rise of mammals, the evolution of humans, and significant climate changes

Plate Tectonics

• Plate tectonics is the theory that the Earth's lithosphere is divided into several plates that move and interact
• These plates float on the semi-molten asthenosphere
• Plate movement is driven by convection currents in the mantle
• There are three main types of plate boundaries: convergent, divergent, and transform
• Convergent boundaries: plates collide, leading to subduction (one plate sliding under another) or mountain building
• Divergent boundaries: plates move apart, resulting in seafloor spreading and rift valleys
• Transform boundaries: plates slide past each other horizontally, causing earthquakes

Rocks and the Rock Cycle

• Rocks are naturally occurring aggregates of minerals
• The three main types of rocks are igneous, sedimentary, and metamorphic
• Igneous rocks: formed from the cooling and solidification of magma or lava, intrusive (granite) or extrusive (basalt)
• Sedimentary rocks: formed from the accumulation and cementation of sediments, clastic (sandstone), chemical (limestone), or organic (coal)
• Metamorphic rocks: formed when existing rocks are changed by heat, pressure, or chemical reactions, foliated (slate) or non-foliated (marble)
• The rock cycle describes the continuous processes through which rocks are formed, broken down, and reformed

Earthquakes

• Earthquakes are sudden releases of energy in the Earth's lithosphere, creating seismic waves
• Earthquakes are usually caused by the movement of tectonic plates
• The focus (hypocenter) is the point where the earthquake originates, and the epicenter is the point on the Earth's surface directly above the focus
• Seismic waves: P-waves (primary) are compressional and travel faster, S-waves (secondary) are shear waves and cannot travel through liquid
• Earthquake magnitude is measured using the Richter scale or the moment magnitude scale
• Earthquake intensity is measured using the Modified Mercalli scale

Volcanoes

• Volcanoes are vents in the Earth's crust through which molten rock (magma), gases, and ash erupt
• Volcanoes are typically found at plate boundaries, especially subduction zones and rift valleys, or at hotspots
• Types of volcanoes: shield volcanoes (broad, gently sloping), composite volcanoes (steep-sided, layered), and cinder cones (small, cone-shaped)
• Volcanic eruptions can be effusive (lava flows) or explosive (ash and pyroclastic flows)
• Volcanic hazards: lava flows, ashfall, pyroclastic flows, lahars (mudflows), and volcanic gases

Tsunamis

• Tsunamis are large ocean waves caused by sudden displacement of water
• Common causes include underwater earthquakes, volcanic eruptions, and landslides
• Tsunamis have long wavelengths and travel at high speeds in the open ocean
• As a tsunami approaches the shore, its speed decreases and its height increases which causes devastating flooding
• Tsunami warning systems use seismic and sea-level data to detect and predict tsunamis

Landform Regions of Canada

• Canada is divided into several distinct landform regions, each with unique geological and topographical characteristics
• The Canadian Shield: a vast, ancient bedrock region covering much of eastern and central Canada, characterized by exposed bedrock, lakes, and low-relief terrain
• The Interior Plains: relatively flat region underlain by sedimentary rocks, used for agriculture and resource extraction
• The Western Cordillera: mountainous region along the west coast, formed by plate tectonics; includes the Rocky Mountains, Coast Mountains, and intermontane plateaus
• The Appalachian Region: old, eroded mountain range in eastern Canada, characterized by rolling hills and valleys
• The Arctic Lands: northernmost region of Canada, characterized by permafrost, tundra, and glaciers
• The Great Lakes-St. Lawrence Lowlands: fertile, low-lying region around the Great Lakes and St. Lawrence River

Glaciation

• Glaciation is the process by which ice sheets and glaciers form and affect the landscape
• Glaciers are large masses of ice that move under their own weight
• Continental glaciers (ice sheets) cover large areas, while alpine glaciers are found in mountainous regions
• Glacial erosion: plucking (rocks freezing to the base of the glacier) and abrasion (rocks scraping against the bedrock)
• Glacial deposition: till (unsorted sediment) and outwash (sorted sediment deposited by meltwater)
• Landforms created by glaciation: U-shaped valleys, cirques, aretes, moraines, eskers, and drumlins
• Glaciation has significantly shaped the Canadian landscape, leaving behind numerous lakes, valleys, and depositional features