What does water do in geological processes?
Erosion, weathering, resevoirs of groundwater, shape the landscape of the continents
How much groundwater is there and why?
100 times more than lakes, oceans, rivers and is unusable because it contains quantities of dissolved material
residence time definition
certain average time water spends in a reservoir
what is the world's water supply?
1.4 billion cubic kilometers
what drives the hydrological cycle?
how does sun drive the hydrological cycle?
evaporating water from the oceans and transporting it as water vapor in the atmosphere
Atmospheric composition (3)
What was the early atmosphere made of?
Methane and Ammonia
What produced today's atmosphere?
Outgassing of CO2, SO2, N, and H2O advent the oceans, and photosynthesis conspired
What is the Ozone?
How/where does ozone form?
Upper atmosphere by splitting O2's
What does ozone do?
Absorbs ultraviolet radiation
4 layers from the ground up
Where does 50% of air lie?
Below Mt. Everest's height
Weight of the overlying air column (thick columns of dense air produce high temperatures)
What happens with pressure and altitude?
What happens with density and pressure?
Density increases with pressure
Where do 50% of molecules lie below?
6 km altitude
What happens with density and relative humidity?
Increases with it
Total kinetic energy of molecules in gas, faster motion=more heat
Average kinetic energy
What happens with temperature and pressure?
Temp increases with pressure, 6-10 degrees Celsius/km
Relative humidity definition
percentage of maximum water content
what happens with maximum of relative humidity and temperature?
maximum decreases with pressure, why houses in MN are dry in winter
why does air move?
pressure differences, flows from high to low
what happens with solar insolation and latitude?
decreases with latitude
what affect all motion?
Coriolis effect definition
deflection of moving objects when they are viewed in a rotating reference frame. In a reference frame with clockwise rotation, the deflection is to the left of the motion of the object; in one with counter-clockwise rotation, the deflection is to the right
Why do the coriolis happen?
the Earth rotates eastward; and the tangential velocity of a point on the Earth is a function of latitude (the velocity is essentially zero at the poles and it attains a maximum value at the Equator)
Where is Coriolis most obvious?
when an object is moving longitudinal
What is weather largely dictated by?
interaction of air masses
air masses definition
large bodies of air with characteristic properties (hot and moist for example) and associated with particular source regions
boundaries between air masses (cold front if moving mass is cold)
What are hurricanes?
1) Low-pressure systems with CCW rotation with rising humid air, air cools and then dries
2) Storm surge, CCW at coast plus Coriolis effect, shoreward transport of water
Average weather conditions and range of variation within the year
What is climate affected by (5)
Latitude, altitude, proximity of water and ocean currents, topography, proximity to standng high/low pressure zones
Orographic effect definition
increase in precipitation driven by adiabatic cooling of air masses rising over topography
river or sheet of ice that flows across the land surface and exists year round
what are the keys to glaciers?
perennial ice, flow
Rheology of Ice (brittle/plastic)
Brittle near surface when dry and/or very cold, plastic at high pressures and when wet
2 mechanisms of movement of ice
Basal sliding, internal shear
Basal sliding definition
Ice column moves as one
Internal shear definition
ice deforms, flowing like a fluid
When is basal sliding most common?
summer months when bed is water saturated
What can result from basal sliding?
What happens in internal shear?
ice deforms, recrystallizes
where is internal shear limited to?
when does internal shear happen?
year round, but faster in summer (wet, soft ice)
What direction is flow always?
downslope, even when "retreating"
what direction does ice flow?
from above snowline to below
Minimum elevation of perennial snow
where does snow melt completely each year?
below the snowline
zone ablation definition
below the snowline
zone of accumulation definition
where snow accumulates above the snowline
What kind of sediment does ice move?
all sizes of clast
how do sediments move with ice?
at the same velocity
where is sediment from in ice?
mass wasting from valley walls (what's on top of ice), glacial grinding and abrasion, plucking
unsorted mixture of mud, sands, pebbles, and larger rocks deposited by glaciers
boulder deposited far from source by glacier or ice sheet
a till deposit
U-shaped valleys definition
streamlined hill formed when glacier overrides till
Where are the three places earth's water?
oceans, ice caps, groundwater
where is 97% of earth's water?
how much does water does the mantle contain?
less than 1%, 0.3% in upper mantle
how is water released?
by volcanism, steam is most common gas in magmas, abundant release during early Earth history
how is water returned to mantle?
what are comets mix of?
ice and dust, substantial portion of water ice
what are some transport processes?
evaporation, precipitation, transpiration, glacier growth and melting, groundwater flow and infiltration, river flow and surface runoff
how do reservoirs grow?
in expense of others, sea level has varied y about 100 m over the past 1 Ma
how fast is interchange between reservoirs?
residence time definition
average time water spends in a reservoir, assumes steady-state conditions
Residence time equation
R= V/F out = V/F in, V=volume, F=flux in or out of reservoir (volume/time)
as water moves through the cycle it..
brings sediment with it, affects tectonics
how does water affect tectonics?
lubricates faults, catalyzes subduction zone volcanism, augments uplift through erosion
How much groundwater is used per day?
400 km squared, 70 year supply without replenishment
water stored in subsurface in pores and cracks
ratio of void volume to total colume of material
primary porosity definition
void space in newly deposited or lithified rock
secondary porosity definition
void space created after rock formation
what lowers primary porosity?
what does cement do to primary porosity?
how does grain size affect porosity?
better sorting raises porosity
how does grain shape affect primary porosity?
round grains raise porosity
specific yield definition
percentage of pore water that can be extractedl
where is specific yield higher?
larger, well-connected pores, extensively cracked rocks
how high does specific yield seldomly exceed?
ability of a material to allow fluids to pass through an interconnecting network of pores
permeability controls (3)
number of conduits, size of conduits, straightness of conduits
how does number of conduits affect permeability?
more conduits, greater permeability
how does size of conduits affect permeability
larger conduits, greater permeability
how does straightness of conduits affect permeability?
straight conduits, greater permeability, cracks and joints increase permeability
what is permeability not simply related to?
porous sediment or rocks that transmit water easily
sediment or rocks with very low permeability
water can percolate down to it from the surface, can be recharged
water cannot reach it from surface, can't be recharged, subject to compaction upon extraction
zone of aeration definition
near-surface region where pore space is not filled
zone of saturation definition
deeper regions where pores are filled
water table definition
surface separating the zones of aeration and saturation (pore space is water filled below the water table)
what are visible expressions of water tables?
lakes and streams
what does water table usually follow?
topography but with less amplitude
what does water table rise with?
rainfall, high in winter/spring, low in summer/fall
key elements of groundwater
water table elevation, horizontal separation, hydraulic conductivity
what changes produce pressure gradients?
according to darcy's law velocities are typically?
what are ground water deposits?
chiefly calcium carbonate, stalactites, stalagmites
what does open porosity compacting result in?
subsidence of ground surface
what does draw down result in?
saltwater intrusion in coastal regions
What are the two regimes of fluid flow?
crossing streamlines, mixing
What are the three factors that affect whether it is turbulent or laminar?
velocity, viscosity, distance to channel
will it be turbulent or laminar if it is moving fast?
will it be turbulent or laminar if it has low viscosity?
will it be turbulent or laminar if the distance to channel is large?
sediment load definition
total of all sediment carried by a flow (stream or air)
bed or traction load definition
never in suspension
suspended load definition
stays in suspension
saltaing load definition
moves by hopping
four categories of sediment loads
bed, suspended, saltating, dissolved load
maximum particle sie that can be carried
what kind of flows have greater competence?
fast, turbulent flows
total quantity of sediment a stream can carry
path of water except at flood stage
natural levees definition
sediment banks rimming channel
flood plain definition
flats bordering channel and covered during floods
stream valley definition
topographic highs delimiting floodplain
path of fastest flow, usually above deepet portion of the stream channel, outside portion of bends, midstream along straights
streams erode outside banks (faster flows), cut banks, widening, deposit on inside bans (slow flow), point bars, narrowing
sediment in fluvial deposits
where do stream deposits occur?
where stream slows down (causing decrease in capacity and competence)
nearly flat surface produced by meandering streams and denudation, indicative of mature landscape, can be rejuvenated by uplift`
A one-hundred year flood could happen two years in a row?
A well-sorted gravel is likely to have greater porosity than a silty sandstone (sandstone with some silt sized grains?
Freshwater is less dense than salt water
Groundwater commonly moves at velocities of meters a day or more?
If you melt all the ice on the planet, very little land will be left exposed
Mantle outgassing occurs everywhere and at all times as water slowly escapes the mantle
Most of the world's oceans are underlain by abyssal plains?
On which side of a river bend would you expect to find a sand or point bar?
Stream long profiles are concave up?
Streams with high discharge and low sediment supply can erode below base level?
Terminal moraines form as the flowing ice in a glacier bulldozes sediment?
The ease of erosion of clasts increases as the size of the clasts decreases, continuing to the smallest clast sizes
The most reasonable velocity for glacier flow is?
There is no strong evidence that the amount of water on Earth's surface has changed dramatically in the last 100 Ma?
Which of the following is the least likely cause of a stream terrace?
Rise in stream base level
Small, steep mountain streams have higher competence than major trunk streams
The ease of erosion of clasts increases as the size of the clasts decreases, continuing to the smallest clast sizes?
Water can both leave the mantle and go back in?