GEOG 205 final Flashcards
define geomorphology
the study of the form of the earth
describe the driving mechanisms of geomorphology
climate/atmosphere, tectonics, biotic, gravity
describe the difference between uniformitarianism and catastrophism
uniformitarianism (James Hutton) believes changes are due to continuous, smaller-scale actions, catastrophism (Georges Cuvier) believes changes are due to sudden, catastrophic, large-scale events
define the processes and forms
processes operate on variable time and space scales, forms are the result of process, driving forces, and setting
understand why studying geomorphology is relevant
hazard assessments, water quality, planetary studies of landforms, climate records, and agriculture
define and provide examples of isolated, closed, and open systems
isolated - energy cannot cross system boundaries (universe)
closed - energy can cross, but no substantial change (earth)
open - both matter and energy can cross boundaries (river)
define negative and positive feedbacks
negative - discourages change in system, self-regulates
positive - encourages change in system
understand the concept of thresholds and equilibrium
thresholds - intensity that must be met for a certain reaction or result
equilibrium - the idea of a self-correcting balance
describe the relationship between drivers and resistances to landscape change and list the forces of each
increase driving force and/or reduce resting force = rate increase and vice versa
drivers - climate, gravity, internal heat/tectonics
resistances - lithology, vegetation, structure
describe the role of time, magnitude, and frequency in landscape change
time - variable levels of time are required for products of change
magnitude and frequency - frequent events have low magnitude (strength), high-magnitude events are more rare
define denudation
any process that wears away landforms and results in decreasing the elevation and relief of a landscape
describe differences/similarities between weathering and erosion
weathering - in-situ breakdown of earth forming materials
erosion - relies on transporting agents and gravity
describe key factors that control weathering
parent rock material, climate/setting, soil, and length of exposure
define the two types of weathering
physical - mechanically breaking down materials
chemical - chemical alteration of composition through different reactions
describe the six types of physical weathering
pressure stress release, thermal expansion and contraction, salt weathering, hydration, freeze-thaw, plants
describe the different types of chemical weathering and provide an example for each
oxidation (iron -> hematite), hydrolysis (water), carbonation (carbon), cation exchange (holding + ions), chelation (materials binding together)
explain why weathering is important in geomorphology
it plays a large process in the creation of soil and landforms
understand the role of weathering in soil formation
need both physical and chemical breakdown to make soil
define soil forming factors
climate, organisms, relief, parent material, and time
define cohesion and adhesion
cohesion - attraction of water molecules to other water molecules
adhesion - attraction of water molecules to solid surfaces
describe differences between clay and sand particles
clay - flat, disc shaped, high surface area, high adhesion, water moves slowly
sand - round, more conductive pore network, low surface area, low adhesion, water moves faster
define mass movements in force balance terms (driving vs resisting forces)
collective term for all gravitational downslope movement of materials, with little or no transporting agent (reference diagram)
what are the basic forces involved in slope stability
shear force - pushing downslope
normal force - pushing into slope
differentiate the main categories of mass movement processes and landforms
heaves - soil creep, solifluction, gelifluction
falls - rock falls, rock topples
slides - translational, rotational
flows - debris flow, mud flow, earth flow, lahars avalanches
define source and sinks in a geomorphology context
sources are where sediment starts moving (erosion) and sinks are where sediment stops moving (deposition)
define key characteristics of a watershed
topographically defined, inputs do not always equal output, watersheds drain into a single common outlet, reference diagram
describe the importance of watershed morphology in understanding geomorphologic processes
watersheds can show key processes at play (weathering and erosion) and parent material and its resistance
what is the equation for calculating drainage density?
drainage density = (channel length)/(area)
describe different drainage patterns and where they might form/what controls their morphology
dendritic - tributaries join larger streams at acute angles
parallel - tributaries form parallel to slope surface
trellis - synclines form valleys
radial - tributaries extend headward reaches upslope toward top of elevation
rectangular - tributaries make sharp ends to enter main channel
centripetal - stream flows downwards towards a central depression
deranged dendritic pattern over run by glacier
define hydraulic actions and abrasion and where they occur in the system
hydraulic action - erosion due to flowing water only (upstream tributaries at highest elevations)
abrasion - debris movement, particles grinding out the stream bed (downstream)
what are the driving and resisting forces in channels?
gravity, planes of weakness, friction of grains, bedforms, channel shape, vegetation
define channel hydraulics’ via discharge and stream power
stream power is a function of discharge and slope, thus a function of watershed position
define the 3 types of sediment transport
dissolved load - solutes dissolved in water, not visible, product of chemical weathering
suspended load - fine grained sediment floating in water column, no contact with bed
bed load - course material, in contact with bed, rolling and saltation
what is the equation used to calculate volume of sediment transport?
sediment transport = (concentration of suspended sediment)x(discharge)
describe the fluvial continuum
- source/high altitude
2a. lower altitude/basal
2b. lower altitude/basal (greater sinuosity) - alluvial fan, delta, or terminus
describe the 4 main types of channels
straight, meandering, braided, anastomosing (2 or more distinct channels)
define factors that drive coastal processes
climate, gravity, parent material, sediment transport/load from rivers, wind, barometric pressure, tides, storms, biology
list and discuss coastal sediment sources
terrestrial deposition (rivers), coastal landforms (beaches, cliffs), off-shore (longshore transport)
define base level and its different settings
surface to which sediment accumulation fills up to or eroded down to, controlled by erosion, sediment deposition, tectonic movement, eustasy (sea level changes)
what are the 5 subzones of coastal geomorphology?
coast, littoral zone, shore, shoreface, and continental shelf
what are the differences between currents, tides, and waves
currents - large water and heat movement, driven by earth’s rotation, wind, sun, gravity, and temperature
tides - vertical rise and fall of water level, driven by gravitation and centrifugal forces of moon and sun
waves - key for coastal erosion and deposition, driven by wind and frictional forces with bed
how do tides form?
tides are caused by the gravitational pul of the moon and the sun, which creates bulges in earth’s oceans. earth’s rotation moves these bulges, resulting in the rising and falling of sea levels at the coast
what is the different wave terminology and how do waves move?
crest (highest part), trough (lowest part), wave height (vertical distance between crest and trough), wavelength (horizontal distance between two successive crests)
motion is circular, but there is still some overall forward motion (reference diagram)
depositional vs erosional coasts
depositional - material at coast deposited, lower wave energy
erosional - coasts eroding form intense wave energy
describe offshore landforms
terminal sediment sink, sediment transported via density (turbidity) currents, examples are submarine canyons/channels
describe turbidite, their formation, and stratigraphic layering
sediment-laden flow of water that moves down a slope, carves channels into slope, splay/fan deposition (grades stratigraphy, debrite-rich turbidite)
what are the key drivers of aeolian transport?
wind, limited by vegetation and soil moisture
describe key component of wind
generated by differences in pressure gradients, coriolois effect (earth’s rotation), friction forces, turbulence and surface roughness, and albedo
what is the wind erosion equation?
erosion = (erodibility of the soil)(local wind conditions)(soil surface roughness)(width of the wind field)(vegetation cover)
define loess
accumulations of wind-blown dust
why are loess present in europe and north america?
they formed during the ice ages, when fine silt and clay particles were carried by strong glacial winds and settles in the regions
define reg
a desert surface covered with coarse gravel, formed when wind removes finer particles, leaving behind heavier materials
define erg
sandy expanses and dune fields (dune seas or sand seas)
define ripples
small asymmetrical ridges related to length scale of saltation
describe ripple formation
wind flows over loose sediment, creating small, evenly spaced ridges and troughs due to the movement of grains by the fluid’s energy
define dunes
asymmetrical hills of sand, larger than ripples, migrate downward via erosion from the windward face and deposition occurs on the slip face
classify different dune types based on wind direction, shape, and sediment supply
barchan, transverse, parabolic, longitudinal, star, draa
define the 3 types of glaciers and how constrained by topography they are
alpine (topographically confined), ice fields (partially confined), continental ice sheets (unconfined)
define climatic snow line and the trends with latitude and altitude
lowest elevation where snow remained year-round
polar regions - high latitude, snow line near sea level
define the 3 milankovic cycles that influence glacial occurances
eccentricity (shape of earths orbit), obliquity (tilt of earth’s axis), precession (wobble of earth)
discuss the importance of glaciers in geomorphology
influences both hydrologic cycle and rock cycle
describe basal shear stress and glens law
the relation between stress and strain is given by glens law, small changes in basal shear stress can produce major changes in ice structure
what are the different crevasse shapes?
longitudinal (where glacier widens), transverse (changes in topography, steep terrains), chevron (edges), radial (terminal toe and edges)
describe warm vs cold based glaciers
warm-based - approximately the pressure melting points throughout their depth and contain water
cold-based - well below the pressure melting point at depth
how does glacial ice form?
snow that doesn’t completely melt throughout the year will accumulate through compaction and recrystallization, snow first transitions to firn and then glacial ice, increases density
how are glaciers classified?
morphologic (shape/form), dynamic (movement), thermal (warm vs cold based)
what are the differences between alpine and ice sheet glaciers?
alpine - form in mountain ranges, valley glaciers confined
ice sheets - continental ice sheets, high latitude, extensive
what is glacier mass balance and its key terms
glaciers always flow downslope, even when retreating, glaciers are open systems
modes of glacial sediment transport
stratified and non-stratified
types of glacial sediment
drift, till (non-stratified, unsorted), outwash (stratified-well sorted), glacio-lacustrine (glacial lake sediments)
what are glacial erosional and depositional features and how do they form
erosional - u-shaped valleys, aretes, cols, horns, hanging valleys, fjords
depositional - glacial erratics, moraine, outwash plain
what is the role of endogenic processes in landscape creation/geomorphology
influence the shape and dynamics of the troposphere
describe evidence for plate tectonics
geometric fit of the continents, geographic patterns in fossils and rocks, paleoclimatic evidence, mountain range patterns, apparent polar wander paths, marine magnetic anomalies, earthquake and volcano positions, hot spots
define drivers of plate tectonic movements
mantle convection (colder material sinks, warmer material rises), ridge push (gravitational force at spreading ridges), slab pull (gravitational force in subduction zones)
describe plate boundary interactions
divergent - spreading centers
convergent - zones of compression/collision
transform - lateral plate movement
what are the different eruption and lava types
effusive eruption (basic, basaltic), explosive eruption (composite, stratovolcanoes), other volcanoes are cinder cones, lava domes, shield volcanoes (basaltic)
why are volcanoes important in geomorphology?
creates and changes landscapes, deposition of ash and particulate matter, affects other biophysical processes
what is the anthropocene?
from anthropo, for man, and cene for new
