S09.323.Karner notes (for what they are worth)
These notes are here to help supplement your class notes. I can state that special characters (superscripts, subscripts, greek letters) will often be distorted due to the inability of this program to accommodate such formatting.
S09.323.L1
No notes. Review syllabus.
S09.323.L2
S09.323.L2
Topics
Hydrologic cycle
Hydrologic Equation
Physical properties of water
Structure
Phases
Latent heat
Chemical behavior
Hydrologic Cycle
[[I stole a figure of the water cycle from the USGS]]
Qualitative description on the movement of water through the lithosphere, hydrosphere and atmosphere.
Energy balance associated with the hydrologic cycle
Water is a unique material that changes through all 3 physical states in Earth’s temperature ranges.
[[Figure of states of water]]
Heat capacity (calorie) = heat required to change temperature of 1 g of water from 14.5-15.5 degrees C. Only ammonia has a higher heat capacity than water.
Latent heat = heat required to change physical state
Very high for water, because of its adhesive properties
80 cal Solid-Liquid at 0??qC
Liquid to gas at 0??qC = 600 cal
Liq-gas (for Liquid at 100C) = 540 cal
(note that if you were to calculate heat needed to melt ice, raise it to boiling, and then vaporize it, you’d need 720 cal/g)
For environmental temperatures: Hv = 597.3 – 0.564 T
Where Hv = heat in calories per gram of water
And T = temperature of water in degrees C
per 1g, sol-liq = 80 cal; 0-25??qC = 25 cal; liq-vap@ 25??qC = 583.2 cal = 688.2 cal/g
This means that evaporating water at environmental temperatures takes less energy than does raising its temperature to boiling and then evaporating it.
What’s a calorie:
1 cal = 4.184 Joules (J) / gram (g) degree K (K)
1 Cal = food calorie = 1,000 cal
Joule = work done by moving a force of 1 Newton (N) by a distance of 1 meter (m)
So, what’s a Newton? N = 1 kg m / sec2 (the force needed to accelerate 1 kg by 1m/s2)
For Earth’s heat balance, the importance is as follows:
If water evaporates at equator and rains elsewhere, then heat is transferred away from equator.
Evaporation = Lithosphere and hydrosphere à atmosphere
Transpiration = plants and animals à atmosphere
Evapotranspiration = all movement of water into the atmosphere
--these involve the transformation of water from liquid to vapor form. We’ll discuss the energy associated with the change of water between physical states.
Movement from atmosphere to hydrosphere or lithosphere
Condensation = transformation of water vapor back into tiny droplets
Precipitation = accumulation of ~ 106 tiny water droplets to form a droplet large enough to fall to surface.
Sublimation = evaporation from solid to gas
Deposition = gas to solid
Molecular structure of water
Single Molecule
Two hydrogen atoms covalently bonded with an oxygen atom. Oxygen has a greater electronegativity (attractive force of electrons in a molecule) than do hydrogen atoms, so the molecule has a dipole charge, with the oxygen side being more negative and the hydrogen side being more positive. This dipole enables water to attract soluble ions, such as sodium, potassium
Molecular attraction and chemical behavior
Water molecules are bonded to each other by hydrogen bonds, which form when a hydrogen atom that is bonded to one electronegative atom is attracted to another electronegative atom. These hydrogen bonds are what give water a high surface tension and cohesion to other water molecules. It also is what provides it with strong adhesive forces to other objects (adhesion occurs when the attraction to the other object is greater than the attraction to other water molecules). Adhesion produces the meniscus in test tubes.
Hydrologic Equation (a.k.a. water budget approach)
There is very little change in the Earth’s water mass through time. Volcanoes and cometary debris contribute on the order of 1 km3 of water per year. What this means is that the known reservoirs of water on Earth must balance through time. If water is added to one reservoir (e.g. a glacier) then that water has to be removed from another reservoir (e.g. the ocean). One can take this approach of accounting to form a general equation for the hydrologic cycle:
Inflow = Outflow ± changes in storage
Meteoric water: water that is presently active in the hydrologic cycle.
Juvenile water = newly added from volcanoes and comets.
Example = a municipal reservoir(ask students for inflows, outflows, changes)
Inflow: runoff (measurable), direct rainfall (measurable), groundwater inflow (potentially measurable)
Outflow: Evaporation (measurable), dam releases (measurable), leakage (groundwater outflow)
± Changes in storage: volume of water in lake
For the Hydrologic equation, we must consider the residence time of water in different reservoirs:
Following added to viewgraph
Estimated residence time of water in different reservoirs
Oceans = 4,000 years
Glaciers = 1,000+ years for small ones, and perhaps 10,000 year for larger ones. (Note that some parts of glaciers record up to a million years of accumulation, but this comes about by ice getting squashed by overlying ice…the ice on the bottom of the pile mostly squishes away from the center of the glacier).
Freshwater lakes ~ 17 years
Rivers = ~15 days
Saline lakes ~ 30 years (???)
Soil water ~ 1 year
Groundwater ~ 10,000 years
Atmosphere = ~ 10 days
If the intervening parts of the hydrologic cycle are short relative to the two primary reservoirs of interest, then this can be a simple calculation. If the intervening parts are relatively long, then the may become part of the accounting process (and potentially more difficult to calculate).
Surfacewater Hydrology
Drainage basin = catchment = all area sloping toward a discharge point = outlined by topographic divides
Groundwater Hydrology
Groundwater basin = volume through which the groundwater flows to reach a discharge point. Bounded by groundwater divides
S09.323.L3
S09.323.L3
Chapter 2: Elements of the Hydrologic Cycle
Topics
Atmospheric circulation
Coriolis Force
Hadley circulation
Evaporation
Heat source
Humidity
Temperature effects
Measurements
Condensation
(Requirements for)
Precipitation
Hydrology terms related to water movement
Precipitation
Evaporation
transpiraton
evapotranspiration
Interception
Infiltration
Soil moisture
vadose zone
water table
groundwater
capillary fringe
Interflow
Throughflow
Overland flow =requires pptt to exceed infiltration and depression storage
Runoff = overland flow+throughflow+interflow
Heat Source for evaporation = the Sun
Average energy = 342 W/m2 over spherical earth
W = Joule/sec
1 cal = 4.183 Joules
Langley = 1 cal/cm2min (but not SI Unit)
Atmospheric Circulation (meteorology)
When you are sitting on the beach at the Equator on a windless day, the wind is really moving about 1700 km/hr; it just happens to match the speed that the ground is moving. When you are sitting near the pole on a windless day, the wind really is not moving velocity = 0 km/hr!
The reason for this is that the wind is tied to the Earth by friction, but that coupling is not perfect…the wind can have different velocities than the ground beneath it.
Follow air form equator to pole to explain wind directions,
Bending of air masses= Coriolis forcing.
Air not really bending. It is the position of the ground relative to the air above it that is changing.
Earth rotates at constant angular speed, but this is a different directional speed at different latitudes
Wind- generated by heat gradients.
Equator gets most heat. Air rises here and moves away from equator.
But it doesn’t flow away in a straight line.
Note Earth rotates counterclockwise in Northern Hemisphere (from west to east).
At equator, speed of rotation = ~ 40,000 km/24 hrs =~1700 km/hr.
Near the poles, the speed of rotation is less- virtually 0 km/hr at rotational pole.
[[Draw ground speed versus air speed]]
ground speed = angular speed
air speed = directional velocity + angular speed
What this means is that air moving from equator towards poles has higher west-eastvelocity than ground beneath it. So it moves towards the east.
By 30 degrees N or South, the air is moving due east. This air descends and returns to the equator to replace the rising air.
THIS MEANS THAT AT GROUND LEVEL, THERE IS A STRONG EAST TO WEST FLOW OF AIR, AND THIS DRIVES OCEAN CURRENTS.
[[Figure 18.16- general wind pattern over Earth]]
just point out wind flow at equator is to the west
=TRADE WINDS.
Atmospheric pressure: Weight of a column of air.
High pressure= greater column weight- air descends here
Low pressure = light column weight- air rises here
At ground level air moves from areas of high pressure to areas of low pressure; at altitude the reverses happens.
By latitude there are two belts of high pressure and two belts of low pressure.
Equatorial low= due to sunlight being highest here.
Subtropical High= where leaving the equator gets bent by Coriolis and eventually cools and descends.
Subpolar low = Air moving from subtropical high heats up and gains water vapor from surface of planet. It collides with are from the polar high and being less dense is pushed over the polar air by frontal wedging.
Polar High = Coldest air on planet causes are to descend.
Note that at the same latitude there also are pressure centers, rather than just a band of pressure. This causes individual storms known as Midlatitude cyclones, but let’s not go there yet (if ever).
Rain = rising air = low pressure
Low pressure = air rises, which means that it will expand and cool by adiabatic expansion.
Deserts = mostly high pressure regions or areas blocked from moisture sources.
Humidity measure of water vapor content of air
Absolute = mass of water (grams) in 1 m3 air
Saturation = maximum mass of water in air before condensation starts
Relative = (Absolute/Saturation) X100
= temperature at which air becomes saturated
Evaporation measurements
Class A evaporation pan = 4’ diameter and 10” deep pan of galvanized metal
Placed in elevated position to allow wind to flow around all sides.
Requires correction factor because a pan of water is a sorry replication of a reservoir. Pan coefficient ~ 0.75 for Midwest study, but range could be 0.5 -0.9 (pulled these outta air).
Nomograph (Figure 2.1). All you need to know is mean air temperature, mean solar radiation, dew point temperature, and wind speed). This is used to estimate the pan coefficient.
S09.323.L4
S09.323.L4
Chapter 2: Elements of the Hydrologic Cycle
Topics
Evaporation
Temperature effects
dry vs. wet adiabat
Measurements
Nomograph
Lysimeter
Condensation
(Requirements for)
Precipitation
Note about dry and wet adiabat versus environmental lapse rate
Environmental lapse rate = temperature change in stationary air
= 5.6??qC/ km
Dry adiabat = temperature drop of unsaturated air as it rises
= 10??qC/km
Wet adiabat = temperature drop of saturated air as it rises.
= 5??qC/km
Note that all desceding air follows the dry adiabat!. This means that saturated air that rises and then falls will become warmer at the starting elevation.
Evaporation – driven by solar radiation
Measured in Watts/meter2 or in Langleys/day
Langley is not an SI measurement. 1 Langley = 1 calorie / cm2 minute.
Evaporation measurements
Class A evaporation pan = 4’ diameter and 10” deep pan of galvanized metal
Placed in elevated position to allow wind to flow around all sides.
A metal pan of water is a sorry replication of a reservoir.
Pan coefficient ~ 0.75 for Midwest study, but range could be 0.5 -0.9 (pulled range outta air).
Nomograph (Figure 2.1). All you need to know is mean air temperature, mean solar radiation, dew point temperature, and wind speed). This is used to estimate lake evaporation.
Evapotranspiration (sum of evaporation plus transpiration).
Measured using a Lysimeter. Container with soil and plants with a soil moisture gauge. Lysimeters are built to resemble field site.
ET = Si - SF + PR + IR - DE
where ET = Evapotranspiration
Si, SF = Soil moisture initial and final
PR, IR = Precipitation and irrigation inputs
DE = Drainage from lysimeter
Variations – many.
Examples = Drainage lysimeter = drainage removed from base to keep track of irrigation balance
Weighing lysimeter = whole lysimeter weighed for loss
Precipitation – caused by adiabatic cooling of air when air is forced to rise through atmosphere. Environmental lapse rate = rate that air cools as it rises through atmosphere without losing or gaining heat from surroundings (= adiabatic). The lapse rate is typically around -6 degree C/ km of elevation. This means that air is cooled as it rises through the atmosphere until it reaches the dew point temperature (i.e. when it reaches saturation).
Specific precipitation processes (need to combine 1 million vapor particles to make a raindrop).
Bergeron Process. Tops of clouds reach freezing, and the relative humidity of ice is much lower than the relative humidity of liquid water. Therefore, once ice begins to form the water vapor quickly condenses to form snowflakes.
Collision-Coalescence process. With large condensation nuclei in the atmosphere (such as dust particles, salt crystals), vapor will stick to these particles and form large rain droplets. These fall through the cloud and run into other vapor particles, thereby coalescing into really large water droplets. These eventually get so large that they break up, and each of the new raindrops continues to collide with vapor to produce more rain.
How to make air rise-
orographic lifting (mountains),
frontal wedging (warm air overruns cold air and is lifted along the front),
convergence (two air masses of similar temperature collide and are forced vertically- this happens over Florida by colliding Gulf of Mexico air and Atlantic Ocean air.
Localized convective lifting (locally airs get heated up and rises, causing small-scale convection cells to develop).
How Precipitation measured:
Rain gauges.- many different kinds exist depending on the particular interest and weather conditions expected.
Recording rain gauge- digital recording of when the rain is falling and how fast it is accumulating (this is good for flooding assessment).
Non-recording- measured daily by person.
S09.323.L5
S09.323.L5
Effective Depth of Precipitation
Arithmetic mean method
Isohyetal Method
Theissen Method
Seasonal Recession Method
Hydrographs
Last time we talked about precipitation and some of causes of it. Key to causing air to reach saturation level is for it to rise adiabatically. How rapid that rise occurs will determine the patterns of precipitation- including quantity, distribution, and rate.
Watershed effects on precipitation
First, most reservoirs are located in watersheds with high annual precipitation. This results in a high return on the investment.
Factors that lead to high water recovery:
1) Access to moist air (for our area that means westerly winds from the ocean)
2) Physical barriers (topography) that cause rapid air lift.
3) Large area of watershed (total runoff proportional to watershed area.
How to determine the effective depth of precipitation in a watershed
Average rainfall = avg. rain depth x area of basin
Where average depth = sum (rain gauges) / number (rain gauges)
If your rain gauge measurements are relatively equal (they rarely are), this would seems to be a useful calculation.
When to use the isohyetal method. When you have lots of time, or your drainage basin and locations of rain gauges are digitized into a computer. Why is this? Because every storm event will likely produce a different distribution of rainfall.
When to use Thiessen Method: When ever you can. Note that once your polygons are mapped out and their areas measured, you just stick new rain data into them via a spreadsheet.
Infiltration capacity= rate that surface water can enter the vadose zone
[[Fig. 2.7: Infiltration curve]]
Different parts to the curve
At the base, fc = equilibrium infiltration capacity. The rate of infiltration when the ground is fully saturated (?). Only the movement of water through interflow and groundwater flow will lead to more infiltration.
For any condition where there is a vadose zone, the rate of infiltration will decrease as the saturation level increases. This rate of infiltration capacity decrease is an exponential decay fit, depending on the amount of time since infiltration began, and a constant representing the ground characteristics (porosity, permeability, slope).
The highest rate of infiltration will occur when water content is lowest (that is the initial infiltration capacity fi). In this case the polar nature of water will cause capillary attraction to the soil particles.
The total infiltration capacity is:
Fp = fc + (fo - fc) e-kt
Conditions:
If infiltration capacity > precipitation rate, all water will infiltrate.
If infiltration capacity < precipitation rate, then some water will become overland flow, and will fill all depression storage.
Stream Hydrographs
Hydrograph = Plot of the discharge of a river at a single location versus time.
Note that a hydrograph can tell you a lot about the characteristics of the drainage basin, because transport of overland flow, throughflow. interflow, baseflow and direct precipitation occur with different time lags.
Baseflow recessions
For drainage basins with prolonged dry periods, contributions to streamflow will eventually be limited to baseflow (i.e. groundwater flow). This causes the water table to drop, which in turn decreases the pressure that is applied to cause groundwater to flow laterally into a stream channel. This drop in baseflow follows a recession curve that tells you about the characteristics of the watershed, including topography, geology, soils and drainage patterns.
S09.323.L6
S09.323.L6
Topics
Finish Ch. 2
Rational Equation
Porosity and intrinsic permeability
Rational Equation
Used to estimate the highest discharge rate for a stream = flood hazard assessment.
Premise: At some point, if it rains hard enough and long enough, the discharge will equal the rainfall average times the drainage basin area, multiplied by a runoff coefficient”
Q = CIA
Where Q = discharge
C = Runoff coefficient (0 to 1 with 1 = highest)
I = average intensity of rainfall
A = area of drainage basin.
Start with example for students to consider and discuss:
Fig. 2.20 = Daily duration curves
Figure demonstrates how three drainage basins in Wisconsin have different discharge rates versus time. By plotting data (discharge in cfs per mi2) the size of the basins become normalized. Thus flow is independent of drainage basin size.
Waucapa River = lowest peak discharge and highest minimum discharge. Interpretation: There is less overland flow and greater base flow contribution. = highly permeable geology
Rib River = Highest peak flow and lowest minimum flow. Interpretation: There is greater overland flow and less baseflow. The geology is less permeable than at Waucapa River
Embarrass River: Intermediate peak and minimum flow. Interpretation: The geology has intermediate permeability properties.
Fig. 2.20 demonstrates the influence of local geology on the streamflow pattern
Terms (we’ll discuss these more later on)
Porosity (n)= volume voids/volume sample x 100
Effective porosity (ne) = volume voids that transmit fluid
For sediments ne = n
What limits porosity is the minimum size of the voids (pore throats) versus the size of the molecules of fluid.
Permeability = intrinsic permeability = characteristics of the porous media that affect the rate of fluid flow (= shape, size, sorting, pore opening sizes).
Note: When you include the factors associated with the fluid, such as specific weight (gamma) and dynamic viscosity (µ), you can derive the hydraulic conductivity
S09.323.L7
S09.323.L7
Topics
Flow in channels
Stream gauging
Manning Equation
Flow in Channels
Flow parameters
components of the sediment load will be influenced by the mineralogy of the rocks (e.g. calcite versus silica cement), and the average grain size for that rock (e.g. mechanical weathering will break down rocks into individual clasts which approach the grain size of the parent rock).
Manning Equation
Used to measure the average velocity of flow in a channel when it is not practical to measure velocities with current meter (e.g. during floods).
V = 1/n x 1.49 R2/3 S1/2
Where
V = Velocity (m/s)
n = Manning roughness coefficient= Emperically-derived (= observationally-derived) value
R =Hydraulic Radius (=A/rho)
S = Hydraulic gradient (dH/dL)
Hydraulic Radius is a measure of the efficiency of a stream channel to transport water.
Note that for a semi-circular channel the R value = circle’s radius/2. Qualitatively what this means is that the average velocity of a stream can be approximated by measuring the half depth of the midpoint of a channel, if that channel were really smooth. The fact that nature doesn’t provide smooth channels results in extra frictional drag on water near the edge of the channel. Consequently the average velocity needs to be measured closer to the edge of the channel (figure 2.23 shows it at 60% of the way to the bottom of the stream.)
See my little sketches
Typical n values
Mountain streams with rocky beds = 0.04-0.05
Winding natural streams with weeds = 0.035
Natural streams with little vegetation = 0.025
Straight, unlined earth canals = 0.020
Smooth concrete = 0.012
Once you have calculated the velocity (V) of streamflow, and cross-sectional area (A) is determined by height of flood, you can quickly calculate total discharge (Q) for a stream.
Note this means the Corte Madera creek could accommodate twice the capacity as the natural stream!
Website set up with images of streams and their manning coefficients
http://wwwrcamnl.wr.usgs.gov/sws/fieldmethods/Indirects/nvalues/index.htm
S09.323.L8
Click here for lecture 8 notes...Due to copious superscripts and subscripts I had to create a separate file for this lecture.
S09.323.L9
Notes embeded in lecture slides
S09.323.L10
Notes embeded in lecture slides
S09.323.L11
S09.323.L12
S09.323.L12
Topics
Groundwater
Water table
Aquifers
Potentiometric surface
Understanding plate tectonic context for California geology
Franciscan Complex (Series)
San Andreas Fault development through time
Glacial cycles
Sonoma County Groundwater context
…with a little help from Italy
Lecture notes: Scanned copies of Dan’s notes.
(Due to the number of subscripts, superscripts and Greek letters
through these next few lectures, I will not be entering them into
Word.)
S09.323.L13
S09.323.L13
This lecture was canceled due to instructor illness.
S09.323.L14
S09.323.L14
This lecture period was used to visit Copeland Creek in order to do the following:
1) Assess where along a river channel it would be best to measure streamflow.
Answer: It is best to do it along a straight section of the channel, so that flow remains relatively uniform across the entire width of the channel. By comparison, measuring the flow at a bend in the stream channel is complicated by the non-uniform depth of the stream (deeper along the cutbank= the outside bank of the river bend). A channel bend can also be physically difficult to wade through and to keep the flow meter stationary in order to make the measurement.
2) Design the streamflow experiment : A) construct a cross-sectional profile of the stream channel and then B) identify where along the profile each measurement will be taken. C) Make measurements at 60% of the depth to the streambed.
Unfortunately, Copeland Creek was running near-dry even a week after torrential rain. This indicates that Copeland Creek is fed by unconfined aquifers with high hydraulic conductivity. It also indicates that the water table fluctuates rapidly following rain events. I would interpret this to mean that Copeland Creek receives relatively little baseflow, and hence wouldn’t be a good creek to use for a baseflow recession experiment.
Some times experiments don’t run the way you hope they would!
S09.323.L15
S09.323.L15
Topics
Soil components
Physical weathering
Chemical Weathering
Physical factors affecting soil development
Soil Profiles
Soil water is the water that is available to plants. As such it is important to know how soils form, what are their compositions, and what physical factors affect their development.
Soils vs. sediment
Soils form in place
Sediments are transported from elsewhere
Sediments and soils are survival assemblages of mineral and rock from which they formed, plus new minerals that formed at the weathering site or the basin where the sediments collect. So soils appear different from parent materials.
Soil- a combination of mineral + organic matter + H2O + air
air= delivers and removes CO2 and O2
water = delivers and removes soluble nutrients necessary for plant growth
Represents an equilibrium state of the surface environment.
Soils are dynamic: if you change any component the soil will change
Soils’ effect on hydrology: Soils determine how water moves through the hydrologic cycle (e.g. infiltration versus runoff, storage for plant use, pollution trap)
The nature, intensity and duration of the weathering process influence the end product.
WEATHERING
1) Weathering- the physical and chemical breakdown of rock
a) mechanical weathering: breaking into smaller pieces (small rocks rather than clay).
Increases the surface area of rock for chemical weathering
Note that mechanical weathering breaks down minerals that have cleavage, whereas those without cleavage will be less affected by it. This leads to quartz being a dominant component of parent rock that survives weathering.
(Hydro students: types of mechanical weathering listed for Information purposes only)
How rocks fragment:
I) frost wedging: freeze-thaw cycle. Vol ice = 9% greater than Vol liquid water. Produces talus
II) Unloading: pressure release as rocks approach surface leads to volume expansion at the top of the rock, and causes outside pieces of large rock bodies to flake off (e.g. exfoliation domes like Half Dome).
III) Thermal expansion: expansion-contract cycle leads to fractures, particularly is the temp change is rapid. Produces shattered rocks in desert.
IV) Biological activity
-roots expand and contract with water availability
- burrowing animals bring fresh rock to surface
-grazing animals- expose fresh rock
V) expansion caused by hydration of minerals (e.g. when mica alters to clay).
b) chemical weathering- creates a suite of new minerals that are stable in surface environment.
Minerals, whether they be igneous, metamorphic, or sedimentary, form in a state that is most favorable for the temperature, chemical and pressure environment in which they formed.
What this means for metamorphic rocks is that virtually all of them have some minerals that are unstable at the Earth’s surface, and so they will undergo some transformation that puts them in equilibrium with their changing environment.
The same is true for igneous rocks; the plutonic rocks did not form at surface temperatures and pressure, and the volcanic ones cooled so quickly that in most cases they did not have time to organize into minerals that were most favorable.
Principal agents of chemical weathering: Water, CO2 and O2 (these occur naturally)
These can alter both the chemical and the physical composition of the rock.
I) Dissolution: affects ionic bonds (e.g. dissolution of halite). Polar water molecule has strong enough charge to break ionic bond between Na+ and Cl-. Other minerals also subject to dissolution: evaporates, carbonates
Calcite dissolution: CaCO3 + 2 [H+(H2)O] (aqueous acid) -> Ca2+ + CO2 + 3 H2O
II) Oxidation (particularly important for Fe). Oxidation state of Fe changed from Fe2+ (ferrous) to Fe3++(ferric). Note that most Fe in silicate minerals is reduced and oxidizes at the surface.
metal oxides Fe3O4 (magnetite)- partly oxidized
Fe2O3 (hematite)- all oxidized
FeO(OH)- limonite = all oxidized
sulfide mineral decomposition (e.g. pyrite):
4 FeS2 + 15 O2 + 14 H2O -> 4 Fe(OH)3 (yellow boy) + 8 SO42- + 16 H+
The H+ and SO42- will combine to form H2SO4 (sulfuric acid)
III) Hydrolysis (particularly important for feldspar decomposition) (H2O + CO2 + OH)
Hydrogen attacks silicates and replaces cations in the crystal structure
e.g. 2 KAlSi3O8 + 2 H2CO3 + H2O -> Al2Si2O5(OH)4 (kaolinite) + 2 K+(aq) + 2 HCO3- + 4 SiO2 (aq)
kaolinite is the main constituent of inorganic soil
SiO2 -> chert
K+ = important nutrient for plants; this makes granites and volcanic rocks good soils.
IV) Ion exchange: once minerals broken down to clay, they often undergo cation exchange:
e.g. Na replaces K
2 Na replace Ca (albitization)
V) Chelation: organic complexing. Lichens do this. Involves bonding metal ions with organic substances- removes cations from rock.
PRODUCTS OF WEATHERING
1) Parent (source) rock residues- those minerals least likely to weather
Rates of silicate weathering:
Hydro students: We didn’t go into geology in any great detail, so the following discussion of Bowen’s Reaction Series is for information only. It should be reassuring to you to know that nearly 100% of igneous rocks are made up of only 9 minerals, which are all based on the combination of silicon and oxygen (silica, which forms the basis of silicate rocks). The silica content of minerals generally increases as you progress from top to bottom, with quartz being composed only of silicon dioxide (SiO2). Quartz is very stable at earth’s surface for a variety of reasons (it has strong covalent bonds that are difficult to break, it has no planes of weaker bonds and so is not easy to fracture, and it is not susceptible to chemical weathering. The consequence of all this is that once quartz-rich rock forms, it rarely is ever destroyed).
The Bowens Reaction series presents the order that minerals form in a magma.
Olivine Ca Feldspar least stable
pyroxene
amphibole
biotite Na Feldspar
K-felds
musc.
Quartz most stable
The point? Quartz, which is at the bottom, is most stable at earth’s surface, and so survives weathering quite well.
2) Secondary minerals- clays, metal oxides & hydroxides
Note that clay is the principal mineral that retains water in a soil. If soil has little clay, it will not be able to store and hence provide water to plants once it’s not raining any longer. Soils that have too much clay tend not to yield water to plants because the water is adhered to the clay particles (tensile stress is greater than the osmotic pressures created by plant roots).
So, to have good soil requires a mix of sediment grain size (mixtures of sand, silt and clay = LOAM).
clay types:
smectite: immature soil
illite: immature soil
kaolinite: more mature
gibbsite:super mature- aluminum ores
diaspore: super mature- aluminum ores
3) soluble materials (shown in decreasing order of abundance):
HCO3- , Ca2+, H4SiO4 (silicic acid), SO4, Cl-, Na+, Mg2+, K+
Rates of Weathering affected by:
1) Rock composition- recall that for the silicate minerals, the Bowen’s Reaction series gives you some guidance about the rates of weathering. The bottom of Bowen’s (quartz) is most stable, whereas the top of the chart are minerals that crystallized at temperature that are most dissimilar to surface conditions. This means that a basalt should weather faster than a rhyolite if put next to each other.
2) Climate: weathering is more rapid in warm and humid environments. The rule of thumb about temperature is that a 10C increase doubles the chemical weathering rate.
A related note about climate is that climate differed through geologic time. Early Precambrian time had no oxygen and no plants, so different controls on weathering existed then. Also recall that glacial time would be different than interglacial time, and so the last several million years have largely been different climatologically than the present.
PHYSICAL FACTORS AFFECTING SOIL
1) Parent material= regolith: Influences the rate of soil formation and fertility (by composition)
Residual soil: forms in place (the survival assemblage after weathering). Slower soil formation because bedrock must be weathered
Transported soil: forms in place on loose sediment transported from elsewhere. Fast soil formation because occurring on material that is already partly weathered.
2) Time: For young soils, the parent material contributes strongly to the characteristics of the soil (i.e. young = A+C, but no B horizon). For older soils, the effects of the parent material diminish and the other effects on soil dominate (climate); lead to formation of B horizon. Overall, older = thicker soil.
3) Climate: temperature and moisture determine the rate of chemical weathering. The importance of chemical versus mechanical weathering will be determined by climate.
Rule of thumb: Increase T by 10C, double chemical weathering rate.
4) Organic material: constitutes 1-100% of soil
decomposition of organic material releases acids that hasten chemical weathering
also- organic material has high water retention
however, decomposition also uses oxygen, which can lead to anoxia if there is unsufficient movement of air or water through the soil. This can lead to concentration nd growth of sulfide minerals, commonly pyrite.
5) Slope:
steep slopes = immature soils. Slope allows water to drain away from rock, which limits the effect of chemical weathering, limits plant growth.
Low mechanical strength of soil versus rock causes soil to erode or suffer from mass wasting relatively quickly.
Parent material becomes very important for the quality of soil on steep slopes!
basins: thick, transported soils, but if poorly drained can lead to sulfide mineral deposition = bad! Parent material of upslope areas determines quality of soil.
Orientation: sunlight important for plant growth, which affects soil formation.
Soil formation is a top-down process
Five horizons of a soil in a Humid Environment (= idealized soil). Note these horizons form in place; they are not transport features as are sedimentary strata.
O = loose and partly decomposed organic material
A = minerals and humus (decayed remains of animal and plant)
O+A = topsoil
E = Zone of leaching and eluviation (washing out of fine components). Soil here is light in color because soluble components are leached out and transported away.
B = Zone of accumulation – material from E collects here, resulting in a higher clay content. Deposition of Fe- and Al oxides + hydroxides form red to yellow coloration; dry climates also include calcite, gypsum and halite, as insufficient water exists to remove the dissolved ions (so they re-precipitate here). Formation of these evaporite minerals leads to lower porosity, decreased intrinsic permeability, and so lower hydraulic conductivity.
C = partly altrered parent material (i.e. disaggregated)
Unaltered Bedrock
O+A+E+B = solum = true soil = that part of regolith with distinct soil horizons
O through C = regolith (=blanket of rock = all unconsolidated materials)
Consider and arid environment with little plant cover
No formation of O or A horizon
No E horizon because no organic acids from above
No B horizon because no E horizon.
So you end up with a C horizon over parent material (regolith)
Soils are classified into 12 Orders.
Alfisol = pedalfer = Al+Fe rich soil
Andisol = young soil on recently deposited volcanic ash
Aridisol = Desert soil
Entisol = lightly weathered soil on recently-deposited sediment
Gelisol = weakly weathered soil in permafrost regions
Histosol = wetland soil (organic-rich, oxygen-poor)
Inceptisol = Young soil with slightly developed reddish B horizon
Mollisol = Grassland soils
Oxisol = Rainforest soils (nutrient-poor due to high infiltration and loss of nutrients)
Spodosol= highly leached, low fertility soils in cold, humid regions
Ultisol = Highly leached, low fertility soils = consists of Fe- and Al- oxides (e.g. laterites)
Vertisol = From very clay-rich parent material, lS09.323.L16
S09.323.L16
Chapter 6: Soil moisture
Topics:
Soil structure (peds)
Soil moisture terms
Field Capacity
Measurements (tensiometer)
Karner’s lecture notes are hand-written; a copy of them are in the Powerpoint viewgraphs for this lecture.
S09.323.L17
I believe that I mislabeled the lectures from here forward. I don't have a lecture 17 in the files.
S09.323.L18
S09.323.L18
Topics
Thermohaline circulation: the ocean’s part in global hydrology
Ocean stratification by density- know the different profiles for equatorial areas versus polar areas)
Stable isotopes: Physical and biological processing leads to measurable changes in isotope ratios, which are stored in rock, shells, and water (solid, liquid and gas).
Note that our coverage of isotopes was very brief, whereas my notes that follow are very thorough. I would like you to know the about the general use of oxygen isotopes to assess water transport, as Oxygen-16 preferentially fractionates into the vapor phase, whereas Oxygen-18 preferentially moves into the liquid phase.
Ocean circulation occurs because of heat imbalances. Same is true for wind. Poles are cold. Equator is hot. Hot goes to cold. But then there are the details.
Thermohaline Circulation : the thread for this lecture
Thermo = heat
Haline = salt
circulation = movement of the ocean water
There are two principal ways that ocean water circulates around the World:
1) Surface Currents
2) Deep water currents
1) Surface Currents
Surface currents are driven primarily by wind.
When you are sitting on the beach at the Equator on a windless day, the wind is really moving about 1700 km/hr; it just happens to match the speed that the ground is moving.
When you are sitting near the pole on a windless day, the wind really is not moving velocity = 0 km/hr!
The reason for this is that the wind is tied to the Earth by friction, but that coupling is not perfect…the wind can have different velocities than the ground beneath it.
[[Fig. 18.16 Wind directions of planet]]
[[Fig. 18.15 Generalized Hadley Cell circulation]]
Follow air form equator to pole to explain wind directions,
Bending of air masses= Coriolis forcing.
Air not really bending. It is the position of the ground relative to the air above it that is changing.
[[Draw Earth with equator and 2 longitude lines]]
Wind- generated by heat gradients.
Equator gets most heat. Air rises here and moves away from equator.
But it doesn’t flow away in a straight line.
Note Earth rotates counterclockwise in Northern Hemisphere (from west to east).
At equator, speed of rotation = ~ 40,000 km/24 hrs =~1700 km/hr.
Near the poles, the speed of rotation is less- virtually 0 km/hr at rotational pole.
[[Draw ground speed versus air speed]]
ground speed = angular speed
air speed = velocity
What this means is that air moving from equator towards poles has higher west-eastvelocity than ground beneath it. So it moves towards the east.
By 30 degrees N or South, the air is moving due east. This air descends and returns to the equator to replace the rising air.
THIS MEANS THAT AT GROUND LEVEL, THERE IS A STRONG EAST TO WEST FLOW OF AIR, AND THIS DRIVES OCEAN CURRENTS.
[[Figure 18.16- general wind pattern over Earth]]
just point out wind flow at equator is to the west
=TRADE WINDS.
We’ll talk about the rest of the air movement later, but for now it is sufficient to know that these winds drive the ocean surface currents.
[[Figure 15.2- average ocean surface currents]]
Note the GYRES = coriolis forcing
Note this means western sides of continents COLD
From Equator to pole we find the following temperature and salinity effect:
[[Figure 14.3- salinity and temperature by latitude]]
explain that temp is high at equator and low at poles
NOW LET”S LOOK AT THE OCEANS IN CROSS SECTION TO SEE HOW TEMPERATURE AND SALINITY VARY WITH DEPTH
[[Figure 14.4- temperature by depth]]
There is no temperature change at the high latitudes- the water is cold from top to bottom.
Near the equator, there is warm water near the surface, but this drops off rapidly by 1 km depth. This drop is called the thermocline.
Why is there a thermocline at the Equator? Surface waters are hot. This causes surface waters not to descend (hot = less dense).
At poles, the water is cold from top to bottom- no heat-induced density change
Density layering
[[Figure 14.5 pycnocline]]
Density is a combination of temperature and salinity
Salinity control
Oceans are salty
~ 35 ‰ salt
Relatively constant, but local concentrations change by the addition or removal of water
Addition of fresh water = runoff, melting of sea ice, melting of glaciers
Subtraction of fresh water= evaporation, production of sea ice, production of glaciers.
Sea ice affects the high latitudes salinity seasonally.
Ocean density also has the rapid change just like the thermocline. It is called the pycnocline.
[[Figure 14.6. Three layers of the ocean]]
1) surface mixed zone ~ 2% of ocean volume. Doesn’t reach the polar oceans.
2) transitional zone ~18% represents the thermocline and pycnocline region.
3) Deep zone ~ 80% of ocean.
This creates a very stable water column near the equator that doesn’t mix much vertically. However, at the poles, there is no density of thermal layering, and so small changes in density or temperature sends water from the surface to the deep ocean.
This process sets up one of the most important heat transport systems in the world- the thermohaline circulation.
[[Figure 15.6: Thermohaline circulation model]]
Formation of sea ice at poles causes density increase and water sinks to the bottom.
Cold water fills the ocean basins.
Warm water moves from equator to pole to replace lost water.
Occasionally this system breaks down.
End of last ice age = fresh water floods N. Atlantic. Sea ice does not increase salinity.
Thermohaline circulation stops.
[pictures of 8200-year event in North Atlantic]
[Picture of Day After Tomorrow]
[[Ruddiman 2.24]]
Warm Gulf Stream and North Atlantic current waters lose heat to cold polar air and hence they cool and lose fresh water to evaporation
Then sea ice forms through a process of salt rejection
Dense water sinks to form North Atlantic Deep Water- NADW
Depth 2-4 km
Similar processes occur in the southern hemisphere and produce
and
[[R 2.26- cross section of oceans showing different water masses]]
[[R 2.28- the effect of replacing ocean water with sea ice]]
Ice has lower heat capacity than water, so doesn’t retain much heat. It also isolates the ocean heat from the air. Consequently, the air cools a lot (30 degrees) above ice sheets.
Also: Increased albedo by ice reduces IR production and so less sensible heat it atmosphere.
Formation of sea ice on heat transfer- sea ice has lower heat capacity and slower thermal conductivity- it isolates the air from the water, and so the air assumes a temperature similar to a glaciated continent rather than an ocean. This moves air temps to –30C rather than 0C.
[[Figure of a mass spectrometer]]
CaCO3 is dissolved with pure phosphoric acid (H3PO4) liberating CO2 gas.
This gas is then analyzed for molecular mass using a mass spectrometer for molecular masses:
12C16O18O = 46
12C16O16O = 44
How this is done in the mass spec. Molecules are ionized using an ion source. This strips an electron off the molecule, giving it a positive change. The molecule is then accelerated by repellor electrodes toward acceleration plates with a slit in them. Once through they are passed through a magnetic field which is set up vertical to the path of the ions. Particles are deflected inversely proportional to mass. A collection device is located at the far end of the mass spec where the ionized particle is counted. Faraday cup or electron multiplier.
d18O (‰) = 1000 x [(18O/16O)sample - (18O/16O)standard / (18O/16O)standard]
Standard = SMOW for water vapor; PDB for carbonate
[Faure Fig. 24.2- the equilibrium conditions of vapor and liquid d18O at 25C]
Water that is evaporated from the ocean is preferentially enriched in light water molecules (d18O 9.2‰ lighter than liquid). This is because lighter molecules have a higher vapor pressure than do heavier molecules. Once in the air, precipitation that occurs preferentially includes heavier molecules, and so water vapor that has traveled a long distance tends to be isotopically very light.
[Faure Fig. 24.3: d18O in precipitation versus mean annual air temperature]
Figure shows that d18Om = 0.695T –13.6
where m refers to meteoric water 18O and T = Centigrade
[[Faure 24.4: Seasonal variations in oxygen isotopes in Camp Century ice core, Greenland]]
Seasonal variations in temperature lead to seasonal variations in the isotopic composition of water. Faure says that during the summer months, when the air is warmer, there is less fractionation of oxygen isotopes (they are heavier at this time) whereas the winter months snow is isotopically light. This pattern extends to glacial and interglacial times as well- they are less negative during interglacial time
Latitude effects on oxygen isotopes
Transport of water vapor is from equator to pole, and the preferential removal of isotopically heavy water leads to a poleward lightening of water vapor.
Storage of ice sheets and the effect on oceanic oxygen isotopes
Average depth ocean = 3800m
last ice age regression = 120m
average snow composition = -35‰
120/3800 x 35fi = 1.1‰ enrichment of the oceans in d18O
In parts of the ocean where other factors don’t compete on oxygen isotope fractionation (i.e. temperature…on the bottom) there preservation of oxygen isotopes is close to this value from glacial to interglacial times.
[[Ruddiman Fig. 7.6- latitude effect on oxygen isotopes]]
Effect on precipitation: correlation of 0.7‰ shift / oC. This means that 1.5 oC equals the isotopic change due to the storage of ice sheets.
Combination of three different parts of climate:
1) Ice Volume
2) Redistribution of fresh water from ocean basin to ocean basin (Pacific fresher than Atlantic).
3) Temperature effect on foram shell chemistry. increase d18O by 0.25‰/degree C
Effect of temperature of ocean water on fractionation of oxygen isotopes in foraminiferal tests
[[Faure Fig. 24.12: Effect of temp on Delta dmin – dwater]]
d18O ranges for oceanic forams = -2‰ to +4‰, where –2 are the planktonic forams, and +4 are the benthics.
[[R. 11.14: Glacial transfer of oxygen and carbon isotopes]]
This figure shows the effects that we expect from oxygen, but the opposite effect from carbon isotopes. This is because carbon behaves differently in the climate system.
d13C (‰) = 1000 x [(13C/12C)sample - (13C/12C)standard / (13C/12C)standard]
Standard = PDB for carbonate
range of d13C = -25‰ for vegetation on land to +2‰ for ocean surface waters.
Two photosynthetic pathways for C: C3 pathway used by trees and shrubs, with an average d13C of –25‰. C4 pathway used by most grasses and some shrubs yield d13C of –13 ‰. But most of the biomass is in the C3 pathway and so land sources have an average fractionation effect of –25‰.
Ocean reservoirs of d13C
1) d13C in carbonate measures the amount of biological activity occurring in an area. When there is more productivity, the oceans get depleted in 12C, and so carbonates for with high 13C content.
2) d13C shows changes during glacial-interglacial cycles. The cause is reduced land biomass during glacial cycles due to loss of surface area to ice sheets. This isotopically light carbon then goes into the oceans, making the oceans lighter during glacial times. This change ranges by about 1/2 ‰ from peak glacial to peak interglacial times.
[[R 11.13- glacial transfers of carbon and oxygen isotopes]]
3) Pumping carbon into deep oceans during glaciations. Organic carbon is light in organisms, and so increased delivery of them to the deep ocean, and their subsequent decomposition there, leads to decreased deep water d13C and increased surface water d13C.
dD (‰) = 1000 x [(D/H)sample - (D/H)standard / (D/H)standard]
Standard = SMOW for water vapor
Oxygen and carbon isotopes, continued
[Faure Fig. 24.3: d18O in precipitation versus mean annual air temperature]
Figure shows that d18Om = 0.695T –13.6
where m refers to meteoric water 18O and T = Centigrade
[[Faure 24.4: Seasonal variations in oxygen isotopes in Camp Century ice core, Greenland]]
Seasonal variations in temperature lead to seasonal variations in the isotopic composition of water. Faure says that during the summer months, when the air is warmer, there is less fractionation of oxygen isotopes (they are heavier at this time) whereas the winter months snow is isotopically light. This pattern extends to glacial and interglacial times as well- they are less negative during interglacial time
Latitude effects on oxygen isotopes
Transport of water vapor is from equator to pole, and the preferential removal of isotopically heavy water leads to a poleward lightening of water vapor.
Storage of ice sheets and the effect on oceanic oxygen isotopes
Average depth ocean = 3800m
last ice age regression = 120m
average ice composition = -35‰ Greenland; -55‰ Antarctica. Average =50‰
120/3800 x 35fi = 1.1‰ enrichment of the oceans in d18O
In parts of the ocean where other factors don’t compete on oxygen isotope fractionation (i.e. temperature…on the bottom) there preservation of oxygen isotopes is close to this value from glacial to interglacial times.
[[Ruddiman Fig. 7.6- latitude effect on oxygen isotopes]]
Combination of three different parts of climate:
*1) Ice Volume from above and elsewhere ~0.01 ‰/m of Sea level change
2) Redistribution of fresh water from ocean basin to ocean basin (Pacific fresher than Atlantic). this one is less important
*3) Temperature effect on foram shell chemistry. increase d18O by 0.23‰/degree C
(Ruddiman says 4.2 C/ ‰ of d18O)
Complication with temperature and isotopic change in high latitudes: Runoff from continents shift the polar water composition to have similar d18O to equatorial waters, whereas the temperature equation above indicates that there should be a difference of about 5‰.
For reason 3 above, planktonic and benthic forams tell you different stories about climate; planktonic have combination of SST and ice volume, but benthics have less temperature change, and so better reflect ice volume changes.
Effect of temperature of ocean water on fractionation of oxygen isotopes in foraminiferal tests
[[Faure Fig. 24.12: Effect of temp on Delta dmin – dwater]]
d18O ranges for oceanic forams = -2‰ to +4‰, where –2 are the planktonic forams, and +4 are the benthics.
[[R. 11.13: Glacial transfer of oxygen and carbon isotopes]]
This figure shows the effects that we expect from oxygen, but the opposite effect from carbon isotopes. This is because carbon behaves differently in the climate system.
Complications with d18O from forams
1) Evaporation and precipitation change isotopes in planktonics readily
2) Changes in water vapor transport can alter planktonic isotopes too (recall that fractionation correlates with transport distance).
Dd18Oc = Dd18Ow – 0.23 DT
Where D = capital Greek Delta
Oc = oxygen in carbonate
Ow= oxygen in water
d13C (‰) = 1000 x [(13C/12C)sample - (13C/12C)standard / (13C/12C)standard]
Standard = PDB for carbonate
range of d13C = -25‰ for vegetation on land to +2‰ for ocean surface waters.
Carbon moves through the climate system in two forms:
1) Organic Carbon = live and dead things
a) Oceanic organic carbon = from oceanic inorganic carbon with d13C = 0‰
b) Terrestrial organic carbon = from CO2 atmosphere with d13C = -7‰
C3 terrestrial plants (tress, shrubs) = -25‰
C4 terrestrial plants (grasses) = -13‰
since most biomass in the C3 type, terrestrial delivery of organic carbon to oceans = -25‰
2) Inorganic carbon = HCO3- CO32- CO2
foram shells made from inorganic carbon, so d13C = 0‰
Measuring transfer of carbon from land to ocean possible because land d13C = -25‰ whereas oceanic d13C = 0‰
glacial to interglacial d13C change due to movement of biomass = 0.35-0.4‰
this is in agreement with the global average change in d13C; local values can be significantly different due to additional causes.
Mass balance of carbon from glacial to interglacial time
land transfer = 530 GT at 25‰
=0.34‰ change
CO2 change from glacial to interglacial time is about 100 ppm. Only 10 ppm can be explained by physical differences in ocean waters (temperature and salinity changes).
Suggestions by Broecker and others.
Glacial time leads to increased global winds. Areas with wind-driven upwelling would experience more of it, causing increase nutrient supply to oceans, and hence more photosynthesis and bioproductivity. This leads to greater delivery of organic carbon to the deep oceans, and more positive d13C in surface waters.
Idea: Carbon sequestration by Iron fertilization of the oceans.
[[Project SOIREE image of photosynthetic algae bloom in Circumantarctic counter current]]
SOIREE = Southern Ocean Iron Enrichment Experiment
Ocean reservoirs of d13C
1) d13C in carbonate measures the amount of biological activity occurring in an area. When there is more productivity, the oceans get depleted in 12C, and so carbonates for with high 13C content.
2) d13C shows changes during glacial-interglacial cycles. The cause is reduced land biomass during glacial cycles due to loss of surface area to ice sheets. This isotopically light carbon then goes into the oceans, making the oceans lighter during glacial times. This change ranges by about 1/2 ‰ from peak glacial to peak interglacial times.
[[R 11.13- glacial transfers of carbon and oxygen isotopes]]
3) Pumping carbon into deep oceans during glaciations. Organic carbon is light in organisms, and so increased delivery of them to the deep ocean, and their subsequent decomposition there, leads to decreased deep water d13C and increased surface water d13C.
[[R: 11.12: Glacial/Interglacial cycles of d18O and d13C]]
dD (‰) = 1000 x [(D/H)sample - (D/H)standard / (D/H)standard]
Standard = SMOW for water vapor
Single-celled organisms consisting of cytoplasm and a test
Primary classification tools:
1) Soft part morphology: protoplasm with pseudopodia (rhizopodia). These serve several purposes- locomotion, and to trap food and bring it in to the protoplasm to be digested.
2) Hard part morphology
Tests built of chambers- cavities that contain the cytoplasm
Adjacent chambers separated by septa, but a connection is maintained with a little hole (foramen) hence the name for this order as foraminiferida
Opening in the last chamber is the aperture, through which the pseudopodia (rhizopodia) extrude.
tests: can be single or multi-chambered.
Multichambered have sutures that attach them together, and the ornamentation on these sutures is a primary feature to distinguish species apart.
If successive chambers partially envelope earlier chambers called involute
If earlier chambers are visible = evolute
Coiling test: If in one plane= planispiral
If in a coil = trochospiral
Each coil in the test = whorl
If chambers are all in one line = uniserial
If in two lines (alternating between two axes= biserial
If in three = triserial
Composition of the tests
1) Organic: chitin-like material
Form unilocular tests (single chambers)
2) Agglutinated (glues together clasts to make test).
3) Secreted (calcium carbonate) or rarely, silica
3a) Microgranular: equidimensional spheres of calcite (mostly late Paleozoic in age)
3b) porcelaneous: translucent to opaque, consist of a thin inner and outer veneer enveloping a thick layer of crystal laths. The outer layer can have crystal arranged parallel to the surface or perpendicular to the surface, this will affect the smoothness of the outer surface.
3c) hyaline: walls consist of lamellae- a new layer grows over the whole test each time a new chamber is added.
3ci) Radial: under crossed Nichols will show an extinction pattern with a cross.
3cii) granular: no extinction pattern under crossed Nichols.
S09.323.L19
S09.323.L19
Mulholland’s Dream (first part of Cadillac Desert video).
This video gives a good introduction to the early days of water rights in California. It is only now that these water rights agreements made in the early 1900s are being undone.
I believe this is VHS 3005 in the Library Media Center.
S09.323.L20
S09.323.L20
Drilling a well
Topics
Site selection
Drilling methods
Steps to ensure water flow
Steps to ensure water safety
Well development
Note that I am still looking for my lecture notes; they
appear to have been written on a back-up computer. I won’t be able to post them until I return to the Bay Area on Monday.
S09.323.L21
S09.323.L21 (materials pulled from Ch. 8 and elsewhere)
Topics
Coastal aquifers
Architecture of sediment deposits determines how
water will flow between the coastal aquifer and the sea.
Architecture for past 2.5 million years is controlled
by glacial-interglacial cycles, resulting in channel and
fill geometries for coastal aquifers.
Sequence stratigraphy (introduced briefly) can
be used to study coastal aquifers using seismic reflection
to identify seismic sedimentary facies.
Saltwater intrusion- Displacement of freshwater by saline water
hydraulic head for groundwater and ocean are in competition;
the stronger force moves the zone of dispersion away.
Passive vs. active saltwater encroachment.
Ghyben-Herzberg principle.
Karner’s notes are hand-written and copied into the powerpoint talk for this lecture.
S09.323.L22
S09.323.L23
S09.323.L24
S09.323.L25