Environmental Changes over Geologic Time

A comprehensive set of vocabulary flashcards designed to aid students in understanding and memorizing key terms related to Environmental Changes over Geologic Time.

Relative dating

A method that produces a qualitative age or an order of events in geological history.

Numerical dating

A method that produces a quantitative age in actual numbers of years since geologic events occurred.

Law of superposition

States that in undeformed sedimentary rock layers, the oldest layers are at the bottom and younger layers are at the top.

Principle of original horizontality

Sedimentary rocks are originally deposited in horizontal layers.

Conformable contacts

Sedimentary layers that have no missing time between them.

Unconformable contacts

Sedimentary layers that have a discontinuity in the geologic record, indicating missing time.

Geologic history

The history of Earth's physical structure and its changes over time.

Ga (Giga annum)

A unit of time equal to one billion years.

Ma (Mega annum)

A unit of time equal to one million years.

Ka (Kilo annum)

A unit of time equal to one thousand years.

Erosion

The process of wearing away rocks and soil, typically by water, wind, or ice.

Intrusion

The process by which magma penetrates existing rock layers, typically forming igneous rock.

Deformation

The change in shape or volume of rocks due to stress.

Basal sliding

Movement of glaciers caused by slipping at the interface between the ice and the ground.

Internal deformation

The flow of ice within a glacier due to its own weight.

Isostatic rebound

The rise of land masses after the ice weight has been removed.

Glacial period

A time marked by significantly colder temperatures and glaciers advancing.

Interglacial period

Warmer periods between glacial periods.

Eustatic sea level changes

Global variations in sea level related to changes in the volume of ice sheets.

Hydraulic pressure

The pressure exerted by water in an aquifer that causes it to move.

Porosity

The amount of empty space in a rock or sediment that can hold water.

Permeability

The ability of a rock or sediment to allow fluids to pass through its pore spaces.

Aquifer

A body of rock or sediment that can hold and transmit groundwater.

Radioactive decay

The process in which unstable atomic nuclei break down into smaller, more stable atoms.

Half-life

The time it takes for half of the parent radioactive atoms to decay into daughter atoms.

Carbon-14 dating

A method for determining the age of organic materials by measuring the amount of Carbon-14 remaining.

Erratic

A large boulder transported and deposited by glacial ice.

Till

Unsorted glacial debris of various sizes including clay, silt, sand, and boulders.

Outwash sediment

Sediment deposited by meltwater from a glacier, typically well-sorted.

Glacial lake sediment

Sediment deposited in lakes formed from melting glacial ice.

Loess

Silt-sized sediment deposited by wind, typically well sorted.

Piedmont glaciers

Glaciers that flow out from valley glaciers in all directions over flatter land, similar to alluvial fans

Ice caps

Thick ice accumulations that cover less extensive areas than ice sheets.

Last glacial maximum

The most recent time period during the last glaciation when ice sheets were at their greatest extent.

Glacial plucking

The process where glaciers pull or pluck rocks from the ground as they move.

Glacial abrasion

The grinding away of rock by the movement of a glacier.

Roche moutonnée

A rock formation shaped by glacial movement, characterized by a smooth, rounded surface (bedrock)

Striations

Scratches or grooves carved into rock by glaciers.

Glacial polish

Shiny surfaces created by glacier abrasion.

Tilting of sedimentary layers

Changes in the original horizontal disposition of sedimentary rock layers due to tectonic forces.

Isostasy

The equilibrium between Earth's crust and the underlying mantle, affecting crustal movement.

Ecosystem demands

The requirements needed for ecosystems to function effectively, including water availability.

Economic water scarcity

When financial constraints prevent communities from using available water resources effectively.

Physical water scarcity

A lack of enough water resources in a specific area to meet the demands.

Dissolved load

The ions dissolved in surface water.

Suspended load

Clay and silt particles suspended in water.

Bedload

The larger particles, such as sand and gravel, that are transported along the riverbed.

Thalweg

The line of fastest flow within a river channel.

Floodplains

Flat areas adjacent to rivers that can be covered during floods, essential for sediment deposition.

Terracing

Formation of abandoned floodplains as landscapes evolve due to changes in climate.

Cone of depression

A lowering of the water table around a well caused by excessive withdrawal of water.

Watershed

An area of land where all the water drains into a common outlet.

Infiltration

The process of water soaking into the ground.

Surface runoff

Water flowing over land, typically after precipitation.

Drainage system

A network through which surface water, flowing downhill, is channeled.

Discharge

The volume of water flowing through a river at a given time.

Gradient

The slope of a river or stream, affecting its flow velocity.

Braided streams

Streams characterized by multiple channels divided by small islands or bars.

Meandering streams

A winding river that flows slowly across a flat landscape.

Base flow

The groundwater that contributes to the flow of a stream or river.

Groundwater table

The upper surface of the saturated zone, marking the transition between saturated and unsaturated soil.

Confined aquifer

An aquifer that is overlain by a layer of impermeable rock.

Unconfined aquifer

An aquifer with no impermeable layer above it; groundwater level fluctuates with the water table.

Sole source aquifer

An aquifer that is the only source of drinking water for a specific area.

Water scarcity and pollution

Issues arising from insufficient water resources and contamination.

Sediment erosion

The wearing away of soil and rock in the presence of flowing water.

Localized fertilizer application

Using fertilizer in targeted areas to minimize runoff into water systems.

Buffer zones

Areas designed to absorb runoff and prevent contamination of water bodies.

Soil erosion mitigation practices

Strategies aimed at reducing soil loss and maintaining healthy landscapes.

Groundwater politicization

Water management that is influenced by political factors.

Watershed management

The coordinated effort to manage water resources within a watershed.

Decaying radioactive isotopes

Unstable isotopes that emit radiation as they transform into stable forms.

Radiometric dating

Determining the age of rocks and fossils based on the decay of radioactive isotopes.

Climate appropriate crops

Crops that are suited to the local climate conditions to promote sustainable agriculture.

Recycling water

Reintroducing used water back into the supply for further use.

Desalinization

The process of removing salt from seawater to make it drinkable.

Nutrient pollution.

When excess nutrients from sources like fertilizers enter water bodies, leading to problems like algal blooms.

Surface or other freshwater

A segment of water resources comprising lakes, rivers, and groundwater.

Ground ice and permafrost

Frozen ground containing ice and soil, often present in cold regions.

Deep glacial grooves

Channeled formations on the rock bed due to glacier movement.

Artesian well

A well drilled into a confined aquifer that causes water to rise under pressure.

Loess

Well sorted silt deposited by wind

Moraines

Pills of till deposited by glaciers

Glacial lake sediment

Sediments accumulated in lakes formed by glacial activity, typically consisting of fine-grained materials such as clay, silt which only deposit in calm water

Kames

Mound-like deposits of sand and gravel formed by melting glaciers, often found in areas previously covered by ice (outwash)

Eskers

Long, winding ridges of sediment formed by the meltwater streams flowing beneath glaciers, composed of sand and gravel (outwash)

Kettle lakes

When outwash forms around melting dead ice (land icebergs) that eventually leaves depressions filled with water, creating small, isolated lakes.

Till

Poorly sorted sediment deposited directly by glaciers, consisting of a mix of clay, gravel, and boulders.

Erratics

Large boulders transported and deposited by glaciers, often found far from their source.

Ground Moraines

Thin layers of till deposited by glaciers as they advance and retreat, forming a smooth, undulating landscape under the glacier.

End/terminal Moraines

Ridges of till deposited at the furthest advance of a glacier, marking the edge of its former extent (till)

Lateral Moraines

Ridges of debris deposited along the sides of a glacier, often forming parallel features to the glacial valley (till)

Drumlins

Streamlined hills formed by glacial movement, typically found in clusters and shaped by the direction of ice flow (till)

Area of Glacial Deposit

Very flat, thick soil

Areas that have been Eroded

Thin to no soil above bedrock, lakes often fill in space

Erosion of rocks underneath glacier

Picks them up and carries to destination; through abrasion and plucking

Stoss side

of a glacier, the side that faces the direction of the glacier's movement and is often smoothed by erosion.

Lee side

of a glacier, the side that is sheltered from the direction of movement, typically characterized by weathering and deposition as the glacier retreats.

Ablation

the toe of the glacier, where it melts

Accumulation

When a glacier gains new snow