ES Vocab

Glacier

a large mass of ice formed by compacted snow that moves slowly down a mountain valley or spreads outward from a center of accumulation

Valley

 a low area between hills or mountains, often with a river or stream flowing through it

Alpine Glacier

 is a glacier that forms in mountainous regions and flows down valleys from high elevations to lower elevations

Ice Sheet

 is a massive, continent-sized glacier that covers a vast area of land, such as the Greenland and Antarctic ice sheets

Sea Ice

 is frozen seawater that forms and floats on the surface of the ocean

Ice Shelf

 is a floating platform of ice that extends from a glacier or ice sheet out over the ocean

Ice Cap

 is a dome-shaped glacier covering a highland area and spreading out radially

Piedmont Glaicer

 is a type of glacier that forms when one or more valley glaciers emerge from the mountains and spread out into a broad lobe on flat ground

Outlet Glacier 

 is a glacier that drains ice from an ice cap or ice sheet into the ocean or another body of water

Zone of Fracture

  is the upper portion of a glacier where crevasses and cracks commonly form due to stresses in the ice

Crevasse

is a deep crack or fissure in the ice of a glacier, typically formed as a result of movement and stress

Zone of Accumulation

is the upper part of a glacier where snowfall exceeds melting, leading to the addition of new ice to the glacier

Snowline (Equilibrium Line)

also known as the equilibrium line, is the boundary between the zone of accumulation and the zone of wastage on a glacier, representing the elevation above which snow persists year-round

Zone of Wastage 

 is the lower part of a glacier where melting exceeds snowfall, causing a net loss of ice

Calving

 is the process by which large chunks of ice break off from the edge of a glacier to form icebergs

Iceberg

 is a large piece of freshwater ice that has broken off from a glacier or ice shelf and floats freely in open water

glacial budget

 is the balance between the inputs (accumulation of snow and ice) and outputs (melting, evaporation, and calving) of a glacier, determining whether it advances, retreats, or remains stable

Plucking

  is the process by which glaciers lift and remove rock fragments from the bedrock as they move, typically facilitated by the freezing and thawing of water within cracks

abrasion

 is the mechanical wearing away of rock surfaces by the grinding action of rock fragments carried by a glacier

Rock Flour

is a fine powder of ground-up rock produced by the abrasion of bedrock beneath a glacier

Glacial Striations

 are grooves or scratches carved into bedrock by the movement of rock fragments embedded in the base of a glacier

Glacial Trough

 is a U-shaped valley carved out by the erosive action of a glacier

Hanging valley

 is a tributary valley that is elevated above the main valley floor, typically formed by the differential erosion of glaciers of unequal size

Cirque

 is a bowl-shaped depression carved into the side of a mountain by the erosive action of a glacier

Arete

 is a sharp ridge formed by the erosion of glaciers on both sides of a mountain

Horn

is a pointed peak formed by the erosion of glaciers on multiple sides of a mountain

Fiord

is a long, narrow inlet with steep sides or cliffs, typically formed by the submergence of a glacial valley

Glacial Drift

 is the general term for all sediment deposited by glaciers, including till and stratified drift

Till

is unsorted and unstratified sediment deposited directly by a glacier as it melts, often consisting of a mixture of clay, sand, gravel, and boulders

Glacial erratic

is a large boulder or rock fragment that differs in composition from the surrounding bedrock and was transported and deposited by a glacier

Stratified Drift

is sediment deposited by meltwater streams flowing away from a glacier, sorted and layered by size and density

Lateral Moraine

 is a ridge of till deposited along the sides of a glacier by the accumulation of rock debris falling onto the glacier's surface from the valley walls

Medial Moraine

 is a ridge of till formed when two glaciers merge and the lateral moraines along their edges combine

End Moraine 

 is a ridge of till deposited at the furthest advance of a glacier's terminus, marking its maximum extent

Ground Moraine

 is a blanket of till deposited over large areas by retreating glaciers, often resulting in a relatively flat landscape

Outwash Plain

 is a flat, gently sloping area of sand and gravel deposited by meltwater streams flowing away from a glacier

Vally Train

 is a long, narrow strip of outwash plain deposited in a valley by a meltwater stream flowing from a glacier

kettle

 is a depression in the ground formed by the melting of a block of ice left behind by a retreating glacier, often filled with water to form a kettle lake

drumlin

 is a streamlined, elongated hill of glacial till deposited by the movement of a glacier, with the steeper side facing the direction of ice flow

esker

 is a long, winding ridge of sand and gravel deposited by meltwater streams flowing beneath or within a glacier

kame

 is a steep-sided hill or mound of sand and gravel deposited by meltwater streams on the surface of a glacier or at its margins

Quaternary Period

is the geological time period that includes the most recent ice ages and the present interglacial periods, spanning approximately the last 2.6 million years

Dry Climate

is a climate characterized by low precipitation and often high evaporation rates, resulting in arid or semi-arid conditions.

Desert 

 is a region characterized by extremely low precipitation levels, often resulting in sparse vegetation and harsh environmental conditions

Steppe

is a semi-arid grassland or prairie ecosystem characterized by low rainfall and dominated by grasses and herbaceous plants

Epheremal Stream

 is a stream or river that flows only briefly in response to precipitation events or seasonal runoff, often drying up during dry periods

Interior drainage

 refers to a drainage pattern where rivers and streams do not flow into an ocean or sea but instead drain into inland basins or endorheic (closed) drainage systems

Alluvial fan

 is a fan-shaped deposit of sediment, typically gravel, sand, and silt, that accumulates at the mouth of a canyon or valley where a stream emerges onto a flat plain

Bajada

 is a series of coalescing alluvial fans formed along the base of a mountain range, typically in arid or semi-arid regions

Playa Lake

 is a temporary, shallow lake that forms in a desert basin during periods of heavy rainfall or snowmelt but often evaporates quickly due to high temperatures and low humidity

Deflation

he process by which wind removes and transports loose sediment and soil particles from the Earth's surface, often leading to the formation of desert pavement and blowouts

Blowout

is a depression or pit in the ground formed by the deflation of loose sediment by wind erosion

Desert Pavement

is a surface covered by closely packed, interlocking fragments of rock and pebbles left behind after wind erosion removes finer sediment

Loess

is a fine-grained, wind-blown sediment composed mostly of silt with smaller amounts of clay and sand, typically deposited in layers over large areas

Dune

is a mound or ridge of sand formed by the wind, typically found in deserts or along coastlines

Slip Face

is the steep, leeward slope of a sand dune where sand grains are continuously deposited and may periodically collapse under the force of gravity

Cross Bed

is a sedimentary structure in which layers of sediment are inclined at an angle to the main bedding plane, typically formed by the migration of sand dunes or ripples

Barchan Dunes

are crescent-shaped sand dunes with horns pointing downwind, formed by winds that are consistently blowing in one direction

Transverse Dunes

 are long, straight sand dunes oriented perpendicular to the prevailing wind direction, typically found in areas with abundant sand and strong winds

Barchanoid Dunes

 are intermediate between barchan and transverse dunes, with characteristics of both types depending on local wind conditions

Longitudinal Dunes

 are elongated sand dunes aligned parallel to the prevailing wind direction, often found in areas with variable wind directions

Parabolic Dunes

 are U-shaped sand dunes with the horns pointing upwind, often formed by vegetation stabilizing the sand near the center of the dune

Star Dunes

are complex sand dunes with multiple arms or ridges radiating from a central point, formed by variable wind directions and sand availability

catastrophism 

The geological concept suggesting that Earth's features are primarily shaped by sudden, short-lived, and violent events

uniformitarianism 

The geological principle asserting that the processes currently shaping the Earth's surface are the same processes that have been at work throughout geologic time

numerical dating

The assignment of a specific age to a geological event or rock layer using numerical values, such as yea

relative date

The determination of the age of rocks or events in relation to other rocks or events rather than in absolute terms

Principle of superposition

The concept that in a sequence of undisturbed sedimentary rocks, the youngest rocks are at the top, and the oldest rocks are at the bottom

Principle of Original Horizontality

The idea that sedimentary rocks are originally deposited in horizontal layers 

Principle of Lateral Continuity

The principle stating that layers of sedimentary rock extend laterally in all directions until they thin out or grade into a different sediment type

Principle of Cross-Cutting Relationship

The principle stating that a rock or fault is younger than any rock across which it cuts

Principle of Inclusion 

The concept that fragments included in a host rock are older than the host rock itself 

conformable 

Layers of rock that were deposited without interruption or significant erosion between them

unconformity 

A surface in the rock record where layers are missing due to erosion or non-deposition

angular unconformity

An unconformity where younger strata overlie an erosion surface on tilted or folded layers 

disconformity

An unconformity where younger strata overlie an erosion surface on horizontal layers 

nonconformity

An unconformity where younger sedimentary rocks overlay older metamorphic or igneous rocks 

fossil

The preserved remains or traces of ancient organisms

paleontology

The scientific study of fossils and ancient life forms

Correlation

The process of matching rock layers and fossils from one location to another 

principle of fossil succession

The idea that fossils succeed one another in a definite and recognizable order 

index fossil 

A fossil that is geographically widespread and limited to a short span of geologic time, used for dating and correlation

fossil assemblage 

A group of fossils found together in a particular rock layer 

nuclear (radioactive) decay

The process by which unstable

isotopes transform into more stable isotopes by emitting particles and

energy

radiometric dating 

The determination of the age of an object based on the measurement of the amounts of certain radioactive isotopes it contains

half-life

The time required for half of a radioactive isotope to decay into a stable element

radiocarbon dating

A method of radiometric dating using the decay of carbon-14 to determine the age of organic materials

geologic time scale

A chronological record of Earth's history divided into eons, eras, periods, and epochs

eon

The largest division of geological time, representing a billion years or more 

Phanerozoic Eon

The most recent eon, characterized by the presence of abundant fossils

Era

A division of geologic time within an eon, characterized by significant geological events

Paleozoic Era

An era within the Phanerozoic Eon, known for the evolution of early marine life and the first land-dwelling organisms

Mesozoic Era

An era within the Phanerozoic Eon, marked by the rise of dinosaurs and the emergence of mammals and flowering plants

Cenozoic Era

The current era within the Phanerozoic Eon, marked by the dominance of mammals and the development of modern ecosystems

Period

A division of geological time within an era, characterized by distinctive rock layers and fossil assemblages

Epoch 

A division of geological time within a period, representing a smaller time unit

Archean

The eon representing the Earth's earliest geological time, from about 4.0 to 2.5 billion years ago 

Proterozoic

The eon following the Archean, from about 2.5 billion to 541 million years ago 

Precambrian

The combined time of the Archean and Proterozoic eons, spanning from Earth's formation to the beginning of the Phanerozoic Eon

Exoplanet

A planet that orbits a star outside our solar system