Module 5-9: Earth Science and Climatology Review

Vocabulary flashcards focusing on climatology, geomorphology (weathering and mass wasting), fluvial systems, coastal systems, and glaciology based on lecture modules 5 through 9.

Climatology

The study of weather patterns averaged over a period of time.

Climate change

A significant change in daily, monthly, and annual averages that typically takes place over tens or hundreds of thousands of years.

Palynology

The study of fossil pollens found in sediments, which indicates changes in water availability and temperature.

Eccentricity

Changes in the shape of the Earth's orbit from nearly circular to markedly elliptical, occurring on an average period of $95,800\text{ years}$.

Obliquity

The variation in the angle of the Earth's axis from $21.8$ to $24.4$ over $41,000\text{ year cycles}$.

Axial precession

The wobbling or circular rotation of the Earth's axis caused by the gravitational pull of the moon and sun on $21,000\text{ year cycles}$.

Spheroidal weathering

A process that takes rocks that are more jagged and weathers them down until they are more round in nature.

Regolith

A blanket of loose, decayed rock that forms in place as a discontinuous cover over unaltered bedrock; also known as saprolite in igneous and metamorphic rocks.

Solutional (Dissolution)

A form of chemical weathering where a mineral passes completely into solution, such as halite or gypsum being leached from rock.

Mass wasting

The down slope movement of earthen materials under the force of gravity.

Shear stress

A stress component parallel to the slope surface that increases as the slope increases.

Normal stress

A stress component perpendicular to the slope surface that decreases as the slope increases.

Angle of repose

The steepest slope at which loose material will remain at rest without moving further down slope.

Creep

The slowest type of mass movement, characterized by an almost imperceptible slow movement of soil down gentle slopes.

Solifluction

The slow flow of saturated soil and regolith common in subpolar regions where a permafrost layer prevents water infiltration.

Debris flow

A rapid flow of saturated masses of particles ranging from clay to boulders, often following heavy rains, reaching speeds up to $50\text{ km/hr}$.

Lahar

A flood of pyroclastic material from volcanic slopes caused by melting snow during an eruption or heavy rains.

Slumping

A type of landslide movement along a curved or spoon-shaped plane where successive blocks rotate downward.

Degradation

The wearing down of earthen material and surface by erosion.

Aggradation

The process of filling and raising the level of a surface by the deposition of sediment.

Discharge

The amount of water passing a given point in a specific period of time.

Dendritic pattern

A tree-like branching drainage pattern with little distortion by folding or faulting.

Braided stream

A stream supplied with more sediment than it can carry, causing the channel to split into an interlacing network of channels and islands.

Suspended load

Typically silt and clay sized particles that remain in suspension and represent the largest fraction of material moved by a stream.

Floodplain

Relatively flat and transitional sediments on either side of the stream channel subjected to overbank flow during flood.

Oxbow lake

A lake resulting from a cutoff meander that remains filled with water.

Littoral zone

The coastal area extending from the highest water line to a point where the water is about $200\text{ ft}$ deep.

Wave refraction

The bending of a wave as part of it drags on the shallow bottom and slows down while the deeper part moves at original velocity.

Longshore drift

The process by which sediment moves in a zigzag pattern along a beach due to swash and backwash from oblique waves.

Sea stack

A pillar or pyramidal shaped rocky island created by the collapse of a sea arch.

Tombolo

A sandy beach that extends perpendicular from the mainland to an offshore island.

Glacier

A large body of flowing ice formed on land from the accumulation and recrystallization of snow.

Firn

A stage of glacial ice formation created by further compression and recrystallization of neve, taking decades to form.

Zone of Ablation

The area of a glacier where snow loss (via melting, sublimation, evaporation, or calving) is greater than snow gain.

Rouche mountonnee

A large boulder with a smooth up-glacier end shaped by abrasion and a steep leeward end shaped by plucking.

Glacial till

Unsorted sediments carried and deposited at the base of a glacier.

Drumlins

Smooth, elliptical or cigar-shaped hills composed of glacial till, aligned parallel to the direction of ice movement.

Arete

A sharp ridge that divides two cirque basins in an alpine glacial landscape.

Tarn

A small lake that forms in a cirque basin behind the lip or edge of the cirque.

Avulsion

distributaries reach a point where gradients are too low and sediment can not be transported, thus, typically during flood, the river breaks its levee and changes course, increasing the gradient and adding to the delta in a new area.

Longshore current

a current in the surf zone moving parallel to the shore. Occurs where waves strike the shore at an angle.

Wave-built terrace

where sediment from cliff erosion is deposited at the edge of the wave - cut platform.

Notch

area of sea cliff undercutting, may cause failure along the cliff front.

Aggradtional landform

Aggradtional landforms are created by the deposition of sand in the littoral zone.

Sea arch

Sea arch - an arch cut by wave erosion through a headland (wave refraction concentrates energy on headland).

Coastal dunes

primarily product of eolian deposition, but usually just appear as irregular mounds without the distinctive shapes of desert dunes, although parabolic form is sometimes found.

Sandspit

sandy beach extended parallel from the mainland beach in a bay or estuary by longshore drift.

Baymouth bars

a spit that has extended all the way across the mouth of a bay or estuary.

Barrier island

permanent offshore or longshore bar, upwards of 6 m above sea level, 1 - 3 mi wid, several mi long and up to 6-7 mi offshore.

Living Shoreline

those created by, or composed primarily of living organisms.

Zone of Accumulation

the area where snow gain is greater than the snow loss.

- Middle of continental glaciers, higher elevations in alpine glaciers.

Abrasion

scraping of the surface of rocks by rock debris carried on the bottom of the glacier.

Striations

liner, thin, shallow scratches in rock surfaces caused by angular sand size d particles being dragged across the surface by glaciers.

Plucking

blocks or fragments of the bedrock are pulled from the surface by the ice and carried along.

Regeleation

refreezing of melted water at the base of the glacier. As a glacier flows over an irregular surface, pressure builds on the up-glacier side of the obstacle, and melting may occur. On the down-glacier side of the obstacle, there is an area of relatively low pressure where the water can refreeze. Refreezing in bedrock fractures helps to mechanically weather the down- ice area of bedrock and also freezes loose debris into the glacier.

Glacial Drift

a general term for all unsorted and sort (stratified) sediments carried and deposited by a glacier.

Erratics

large boulders transported far from their source.

Terminal moraine

curving, irregular ridge which marks the farthest advance of a glacier.

Recessional moraine

similar to a terminal moraine, but created when a receding glacier stops temporarily and deposits new material.

Ground Moraine

blanket or continuous layer of unsorted glacial till laid at the base of a glacier.

Kettle

formed when an isolated ice block left by a retreating glacier is surrounded or covered by outwash or morainal material, then the ice melts, leaving a depression that usually fills with water.

Esker

ribbon or sinuous shaped ridge created by the clogging of a meltwater stream underneath of a glacier.

Kame

a small hill, knob, or mound of sand and gravel (till deposited by a subglacial stream as an alluvial fan or a delta.

Valley glacier

ice mass within a valley originally formed by stream erosion.

Cirque glacier

originates in a cirque, or bowl-shaped recess of a mountain. scooped out by a glacier, several of which may join to form a valley glacier.

Piedmont glacier

a large ice lobe that has spread out from the mouth of a valley at the base of a mountain range, multiple valley glaciers may coalesce here.

Glacial valleys

have a characteristic U shape, also called a glacial trough, that is straighter than stream formed valleys.

- The valley prior to glaciation was V shaped because it was formed by stream erosion, but glacier has carved out the sides and bottom to make it U shaped.

Fjord

a glacial valley which intersects with the ocean and has been flooded by seawater.

Col

a pass or saddle-like depression along an arete.

Lateral moraine

moraines along the side edges of a valley glacier.

Medial moraine

moraine formed in the middle of a valley glacier by the junction of two lateral moraines where two valley glaciers converge.

Topographic Effects

The wind direction and overall wind strength can be affected by mountains and coasts that will in a sense serve as barriers. While also causing the descending and ascending process above.

Air Circulation

Descending dry air absorbs moisture while ascending moist air releases moisture.

Non-Anthropogenic Causes

No human involvement

Chemical Weathering

breakdown of minerals by chemical reactions with the atmosphere or hydrosphere

Carbonation

natural creation of a weak acid by water reacting with carbon dioxide, followed by reaction of the acid and minerals

Deserts - thin salty soils, physical weather is prominent

Landslide

slope failure along a definitive slippage plane as a block of material.

Rockslide

movement of rocks along a bedding plane, joint, or other plane of weakness.

Soil creep

result of alternating freezing and thawing of soil, or alternate wetting and drying

Meandering

A meandering stream is one that exhibits many bends and turns, formed and maintained by erosion of banks and deposition on point bars.

Straight

either artificial or structurally controlled.

Downcutting

caused by the abrasive action of sediments that are rubbed and dragged across bedrock, thus lowering the stream channel elevation. e.g. Grand Canyon, but occurs in all streams.

Stream Piracy

headward erosion by the first stream causes the head of that stream to intersect with a second stream, resulting in the waters of the second stream to flow down the channel of the first stream.

Bed load

particles too large to remain in suspension, and move only when sufficient velocity is present. Bed load can move by rolling, sliding, saltating, or temporarily in suspension in flood.

Deltas

sediments deposited at the mouth of streams due to velocity decreases where they oceans or a lakes.

Alluvial fans

stream deposits that accumulate in dry basins at the foot of mountains.

Meander bend

a bend in a river where erosion is occurring on one bank and deposition on the other.

Natural levee

a ridge of deposited sediment on top of the banks of the channel created during successive flooding events and consisting of the most coarse overbank sediments.

Backswamp

a low swampy area behind the levees t hat retains floodwaters sometimes long after high water recedes.

Yazoo stream

tributary that flows parallel to main stream because it can not overtop natural levee.