Physical Geography Part 3 UWEC

Inner Core

solid because of intense pressure
~2,414km thick; 4-5,000 Celsius
Primarily Iron and Nickel

Outer Core

Liquid
~2,000 km thick; 4-5,000 Celsius
Iron, Nickel

Mantle

Solid; ~2,880 km thick
Heat increases as you get deeper (700-4,000 Celsius)
Asthenosphere & Lithosphere

Asthenosphere

Least rigid portion of Earth’s interior in the upper mantle
Flows slowly under extreme heat and pressure
The plastic mantle

Lithosphere

Earth’s crust and portion of the uppermost mantle directly below the crust (~70 km down)
Rigid mantle

Crust

Continental and Oceanic
SI + O = 74.3% (other are Al, Fe, Ca, Na, K, Mg)

Continental Drift

1912 Alfred Wegener
based on geologic evidence
Convergent, divergent, transform

Seafloor spreading

Magnetic reversals
Age of seafloor
Magma flows up to mid ocean ridge
Can date the rocks

Mineral

Inorganic natural compound
specific chemical formula
Crystalline structure
most abundant is SiO2

Rock

assemblage of minerals bound together
Can be amass of single mineral
Undifferentiated material
Solid organic matter

Igneous Rocks

Cools and solidifies from magma
Intrusive cools below surface and slowly
Extrusive cools on surface and quickly

Sedimentary Rocks

weathering disintegrates and dissolves rocks into grans/fragment — clasts
erosion by gravity, wind, water, and ice carries clasts
Clastic forms by compaction or cementation
Chemical forms by chemical precipitation of minerals

Metamorphic Rocks

Altered and metamorphosed
subject to intense pressure or heat
Igneous or Sedimentary rock + high pressure/heat

Geomorphology

A branch of science concerned with the form of Earths surface, the processes by which it is shaped, how these change through time and space

Endogenic processes

operate within earth
Pushing or building up the lithosphere
Pull or draw down the surface
Long term
explains why there are mountain belts

Exogenic Processes

at or near surface
Wear down highs on surface
Fills in lows on surface
Every day

Uniforitarianism

processes operating now have h=operated the same throughout time
Things functioning now have to have happened in our geologic history

Divergent

spreading center
seafloor spreading
rift zones
North American Terranes

Convergent

areas of crustal collision and subduction
Oceanic crust denser than continental
Subduction zones

Transform

sliding past each other
San Andreas Fault

Friction and pressure build up and releases as an earthquake

Stress

tension, compression, and shear

Strain

how rocks respond to stress via folding or faulting

Folding

bending land deformation of beds of rock strata from compression
Monocline, Syncline, Anticline

Faulting

Displacement and fracturing between two portions of Earths crust
Normal, thrust, Strikeslip

Monocline

resembles carpet overlaid on stairs
up/downward deformation
Folding

Syncline

regional compression
trough-shaped downward fold
Rock strata slope towards central axis
Folding

Anticline

Arch shaped upward fold
Rock strata slope downward away from axis
Folding

Normal Fault

tension
One side moves vertically compared to the other
Horst and Graben topography

Thrust/Reverse Fault

Compression
Fault plan forms low angle relative to horizon
Overlaying block moves over underlying block
Shallow

Strike Slip Fault

Lateral Shearing
Horizontal movement along fault line
Left or right lateral
San Andreas Fault
Often associated with Earthquakes

Volcano

structure in crust with opening vents where magma rises, collects, and erupts

Pyroclastics

pulverized rock and clastic materials ejected violently

Viscosity

low - like water
high - like honey

Crater

circular depression caused by volcanic activity

Caldera

depression formed due to magma chamber collapse

Cinder Cone

small, conical, made of pyroclastic, conical, and scoria ejected from central vent

Effusive eruptions

outpourings of low viscosity magma that produces enourmous volumes of lava
May come single vent or fissures that are continuously flowing

Explosive eruptions

violent eruptions from magma, gas, pyroclastic pressure buildup

Bedload

coarse material transported on bed
Saltation, traction
sand and gravel

Suspended load

fine grained particles held aloft in water column
deposit when velocity falls
silts and clays

Straight

single channel
low energy
typically restricted by underlying geology

Meandering

single channel
Variable migration rates
moderate energy

anastomosing

2+ channels
Something causes the channel to break apart
Lower migration rates
moderate energy

braided

many wide, shallow channels
abundant sediment
High energy

Graded streams

equilibrium
Stream able to transport all sediment received from slopes in a water shed

Ungraded streams

adjusting to change
Change in base level
Waterfalls, knickpoints, canyons

Glacier

river of ice flowing under its own weight on land or floating as an ice shelf

Creep

plastic flow
Occurs within ice
melting and refreezing

Basal Slip

meltwater and mud lubricates glacial bed
Entire mass slips along ground

Fjords

narrow inlets that valley glaciers flow throw

Cirques

aka corries
bowl shaped amphitheater like depressions
Carved into mountains and valley sidewalls at high elevations

Nunatuk

lonely mountain

Aretes

thin, jagged crest separating two glacial valleys
looks like a serrative knive or saw blade

Col

low point on artete

Horn

aka pyramidal peak

Kames

conical glaciofluvial deposits

Eskers

long, narrow, winding fringe of sand and gravel

Outwash plain

occur in front of melting glaciers

Barchans

crescent shaped
horns pointed downward

Barchanoid ridge

wavy, asymmetrical

transverse

long, slightly sinuous, asymmetrical

Longitudinal

linear, slightly sinuous, ridge shaped

Star

pyramidal shaped with 3+ radiating arms

reversing

asymmetrical rdige

parabolic

crescent shaped with open end facing upwind

Nebkha

form within low lying plant canopy