GEOG 205 Global Changes

Geological Time Scale

A system for understanding Earth's history that classifies geological strata based on relative dating through the law of superposition.

Anthropocene

A proposed epoch that reflects significant human impact on Earth's geology and ecosystems, complicating its precise classification.

Cenozoic Era

The most recent geological era, beginning 66 million years ago, characterized by the dominance of mammals and the development of modern climate.

Quaternary Period

The most recent period within the Cenozoic Era, starting about 2.6 million years ago, known for its ice ages and human evolution.

Pleistocene Epoch

An epoch within the Quaternary Period, lasting from about 2.6 million years ago to approximately 11,700 years ago, marked by repeated glacial cycles.

Holocene Epoch

The current epoch that began around 11,700 years ago, characterized by the development of human civilizations.

Half-Life in Radiocarbon Dating

The time required for half of a radioactive isotope, like Carbon-14, to decay; critical for estimating the age of organic materials.

Albedo Feedback Loop

A climate process where increases in ice cover result in greater reflection of sunlight, leading to further cooling and ice accumulation.

Paleomagnetism

A method for dating ocean sediments using the magnetic orientation of minerals, linked to Earth's historical magnetic field reversals.

Dendrochronology

The scientific method of dating trees by analyzing their ring growth patterns, used to calibrate radiocarbon dating.

Striations

Scratches or grooves on rock surfaces left by glacial movement, which indicate the direction of glacier flow.

Drumlin

Tear-shaped hills formed by glacial activity, which also indicate the flow direction of the glaciers.

Glacial Till

Unsorted material deposited directly by a glacier, including a mixture of rock sizes from clay to boulders.

Terminal Moraine

A sedimentary feature formed at the farthest advance of a glacier, marking its maximum extent.

Coriolis Effect

The deflection of moving objects due to Earth's rotation, affecting wind and ocean currents.

Photosynthesis

The process through which plants capture sunlight to synthesize foods from carbon dioxide and water, releasing oxygen.

Latent Heat

The heat absorbed or released during a phase change of a substance without a change in temperature.

Sensible Heat

The heat energy that can be felt and measured by a thermometer; associated with changes in temperature.

Geological Time Scale

A system of chronological dating that relates geological strata (stratigraphy) to time, used to describe the timing and relationships of events in Earth's history.

Cenozoic Era

The most recent geological era, beginning about 66 million years ago and continuing to the present.

Quaternary Period

The most recent period in geological time, starting 2.6 million years ago and consisting of two epochs: Pleistocene and Holocene.

Anthropocene

A proposed geological epoch that highlights the significant human impact on Earth's geology and ecosystems.

Paleomagnetism

A dating technique based on the magnetic properties of rocks that helps determine the age of ocean sediments.

Radiocarbon Dating

A method for determining the age of an object containing organic material by measuring the amount of Carbon-14 it contains.

Half-Life

The time required for half of the carbon-14 in a sample to decay, commonly used in radiocarbon dating.

Dendrochronology

The scientific method of dating tree rings to study past climate and environmental events.

Albedo

The measure of the reflectivity of the Earth's surface, expressed as a percentage of incoming solar radiation that is reflected.

Hadley Cells

Large-scale atmospheric convection patterns that result in the transport of heat and moisture from the equator to the poles.

Sensible Heat

Heat that causes a change in temperature; it can be felt and measured.

Latent Heat

Heat absorbed or released by a substance during a change in its physical state without a change in temperature.

Greenhouse Effect

The warming of Earth’s surface due to the trapping of heat by greenhouse gases in the atmosphere.

Non-Anthropogenic Greenhouse Gases

Greenhouse gases that are not caused by human activities, including methane, nitrous oxide, and water vapor.

Climate vs Weather

Climate refers to long-term averages of temperature and precipitation, while weather is short-term atmospheric conditions.

Equinoxes and Solstices

Annual events marking the change of seasons, with solstices marking the longest and shortest days, and equinoxes marking equal day and night.

Tundra

Polar grasslands with permafrost, characterized by extremely cold long winters and a brief summer.

Boreal Forest

A biome just south of the tundra with short mild summers and long, dry, cold winters; dominated by coniferous evergreen trees.

Temperate Deciduous Forest

A biome with moderate temperatures, long warm summers, and significant precipitation; examples include regions like Vancouver.

Desert

A biome with low annual precipitation and high evaporation rates, found in various climate zones, can be very hot or very cold.

Temperate Grasslands

Biomes such as prairies with cold winters and dry summers, characterized by grasses and minimal tree growth.

Tropical Savanna

A biome with long dry seasons alternating with heavy rain seasons, typically found near the equator.

Tropical Rainforest

A biome near the equator with high humidity, moisture, and warm temperatures, characterized by dense vegetation.

Glacier

A large accumulation of crystalline ice, snow, rock, and sediment that moves downhill under the influence of gravity and its weight.

Firn

A denser, compressed layer of snow that forms when accumulated snow survives a melt season.

Drumlin

Tear-shaped hills formed by glacial movement, indicating the direction in which the glacier advanced.

Striations

Scratches on rocks caused by the movement of glaciers, indicating the direction of ice flow.

Terminal moraine

Deposits left at the edge of a glacier, indicating the maximum extent of the ice.

Albedo Effect

The reflection of solar radiation by ice or snow that contributes to further cooling of the environment.

Ewing-Donn Theory

Suggests that an ice age begins when the Arctic Ocean is free of ice; warmer temperatures lead to more moisture and snowfall, accumulating ice

Forams

Single-celled organisms with calcium carbonate shells used to study paleoclimates.

Oxygen Isotope Ratio

The ratio of Oxygen-18 to Oxygen-16 in foram shells or glacial ice, which reflects changes in ice volume during the Pleistocene.

Younger Dryas

A stadial, a short-duration cold event occurring approximately 12,900 to 11,600 years ago.

Stadial

A cold period occurring within a glacial or interglacial time.

Interstadial

A warmer time between stadials.

Palynology

The study of pollen and spores to detect past climate changes.

Glacial Lake Missoula

A proglacial lake that existed during the last ice age, associated with significant flood events.

Catastrophism

The theory that the Earth's systems were shaped by catastrophic events rather than continuous processes.

Uniformitarianism

The principle that the processes occurring in the past are the same as those occurring in the present.

Eustatic Change

A global change in sea level caused by differences in water volume.

Isostatic Change

A local rise or fall in land levels, often due to glacial weight.

Regression

A decline in relative sea level; occurs as ice sheets grow and eustatic sea level decreases.

Transgression

An increase in relative sea level, resulting in the flooding of land.

Glacial Lake Outburst Floods (GLOFs)

Floods caused by the sudden release of water from a glacial lake due to the collapse of a dam, often impacting remote communities.

Younger Dryas

A short, cold climatic event that occurred around 12,900 to 11,600 years ago, characterized by the re-advancement of glaciers in regions like Nova Scotia and New Brunswick.

Stadial

A cold period occurring within a glacial or interglacial time, such as the Younger Dryas.

Interstadial

The warmer period that occurs between two stadials.

Palynology

The study of pollen and spores, which helps detect past climate changes by identifying plant communities.

Haley Theory

The theory linking dense, cold, salty water formation to cooling in the North Atlantic, as part of the Younger Dryas explanations.

Eustatic Change

Global sea level changes caused by variations in the volume of water, such as during glacial melting.

Isostatic Change

Local changes in land levels caused by the weight of glacial ice, leading to land rising or falling.

Regression

The decline in relative sea level that occurs as ice sheets grow and global sea levels fall.

Transgression

The increase in relative sea level, resulting in flooding of land as ice melts and sea levels rise.

Channelled Scablands

Landforms created by rapid movement of large volumes of water over a short time, leading to significant erosion.

Doctrine of Catastrophism

The theory that Earth's features result from large-scale, catastrophic events