Frames of Reference
March 28, 2007
Previously: v=v’+V, r=r’+R, etc
Medium for light waves? “eather”
Interferometer: E1+E2=Etot, Intensity = |Etot|^2
Vearth=30km/s
c=3×10^8m/s
B=V/C = 10^-4
t1=2(l1/c)*(1/(1-B^2))
t2=2(l2/c)*(1/root(1-B^2))
Assuming ether at rest
(t1-t2)@theta=0 – (t1-t2)@theta=90 = B^2*(l1+l2)/c
Michaelson kept getting B=0
Fitzgerald-Lorentz contraction: dx = dx/gama
gama=1/root(1-B^2)
Einstein-> 1. No such thing as absolute motion, no preferred coordinate system… its all relative
if the ether is at rest there is a preferred system.
2. All inertial observers see the same value for ‘c’
light plays by its own rules: not v=v’+V
Lorentz-Xform
r=ct and r’=ct’ then r!=r’+R
[x';y';z';ct']=L*[x;y;z;ct] where (r^2-c^2*t^2)=(r’^2-c^2*t’^2)
this is fullfilled by:
x’=gama(x-ct*v/t)
y’=y
z’=z
ct’=gama(ct-xv/c)
transform matrix [gama, 0, 0, -gamaB; 0, 1, 0, 0; 0, 0, 1, 0; -gamaB, 0, 0, gama]
Time dilation
t2-t1= gama ((t2-t1)-(x2-x1)*v/c^2))… taken from ct’=gama(ct-xv/c) -> t’=gama(t-xv/c^2)
if X2=X1
dt’=gamadt iff |B|<1
dt’ > dt
In the same way you can do Time dilation you can also do length contraction.
Plate techtonics
November 1, 2006
Plate techtonics -> equivelent of Survival of Fittest in Biology
3 major Boundry Types
- Ridge
- Divergent margin
- Formation of new oceanic crust by sea floor spreading
- Ocean crust -> denser, more mafic, basalt
- Extensional Regime, normal faults, shallow seismicity
- High Heat flow, decompression melting
- Intrusive igneous -> gabbro and basalt (essp. pillow basalts)
- Highly fractured rocks -> alot of water goes through -> causes differences in carbon weathering
- Tends to fault in three geometric paterns (third often failing to spread)
- Tends to also have reafs at shelf slope break
- Starts by bowing up, then breaking, finally filling with lakes then ocean
- Oceanic crust is much thinner than continental crust
- Convergent Margin
- Recycling of old, cool oceanic crust (subduction)
- Older = Colder = less boyant
- Reverse or thrust faulting
- Deep seismicity
- Increaed Temp = Partial melting of mafic crust = felsic magma
- Compression leads to deformation, metamorphism and mountain building
- Water, accumulated in pourse ocean basin
- Water brought down into asthenosphere = decreasing melting point = more rising magma = mountain building
- Also, happens in Continent Continent collision (India subducting under Eurasia) -> causes deformation = himalias
- Also, happens in Ocean Ocean collision -> causes island arc = japan
- When passive margin collides, subduction reverses causing forlorn basin (like western interior basin in N. America)
- Transform margins
- No new crust forms
- Shear regime -> strike-slip faults, shallow seimicity
- San. Andres
- Hot spots are fixed points, thus things like Hawaiian islands, show direction and rate of plate movement
- Magnetic liniations -> lavas on land dated, and reversal history -> reversal history matched to magnetic liniations, giving us time frames
Driving Forces
- Mantal Convection (differences in heat)
- Ridge push or slab pull? -> slab pull is thermal model, push is topographic model
- Subducted material goes down to the core mantel boundry
- Icehouses and Greenhouses, match up with rates of volcanism
- The Wilson Cycle (200my cycle), length of ocean basins determains CO2 levels
Implications
Rivers
October 16, 2006
Hypsometric profile (a significant portion is between 2 and 0 or -4 and -6)
Trenches (found where plate is subducting)
Abyssal planes (Oceanic crust spreading away from trench tword subduction)
Elevation = f(uplift – erosion) or techtonic activity – climate
Both uplift and erosion do about .01 – 10 mm/y
A difference of .5mm/y -> 5 km over 10My
Agents of Sediment removal
- Glaciers -> not alot of work
- Streams -> doing alot of work
Hydrologic cycle (Evaporation and Precipitation)
- Oceans E>P
- Land P>E
Streams are small (1 bases point) and short lived (2 weeks), but they do all the work
Underground water -> huge amount, flows tword sea, we don’t know alot about it (could be HUGEly important, but noone knows)
Rivers
- Amazon is in rainforest (hot and wet) so its not a surprise it has a high flux to drain ratio (heat and pressure are the controls on chemical weathering
- Water Table -> cut off between surface and ground water
- Laminar flow vs Turbulent flow (laminar is mellow, turbulent causes erosion)
- Sheet flow vs Channel Flow (sheet is water across land which forms into channels)
- Controls
- Velocity of flow (function of gradiant)
- Geometry (depth, shape)
- Density and viscosity (almost always water)
- Surface roughness (what its moving over)
- Infiltration capacity
- Pre-existing features (special things)
- Friction is a good control of velocity
- Streams deposit in point bars (where water is slowest)
- Flooding causes fine grain to deposit in plane around the river
- Channel types
- Broad and shallow (arid environment, fast, desert flash flood)
- Deep and narrow (meandering streams, human enviornment, mostly suspended load, more coheasive soil)
- Channel Pattern
- Proximal, Aird climent, bed load streams
- Distal Humid Suspended load
- Grain size is a function of flow velocity above mud
- Below sand -> clays stick together acting like larger particals
- Bedload -> stick to bottom, move through rolling, sliding, saltation
- Creates bedform
- size of particals = competence, controlled by speed
- Number of particals = discharge
- grains build up in beforms (like sand dunes)
- Ripples are 1-3 cm
- >3cm = dunes (some times fractals)
- Ripples form at low velocity
- Dunes at high
- Flow Regine concept
- Suspended load -> carried through turbulation
- Types of Streams
- Aluvial Fans
- Poximal
- Arid -> High velocity
- Intermittant
- Immature
- Bedload
- Braided
- Broad Shallow channels (really shallow)->Dominately bedload
- Transporting sand
- arid to semi-arid->Sparse vegitation
- Easily eroded banks
- Veriable flow
- Course to Medium Grained
- Poor to Moderate Sorting
- Meandering Stream
- Has the cutbank and point bar (one is on the other side of the other)
- Fining upword sequance
- Oxbow lakes (abandoned loops due to flooding eroading a new path)
- Distal, humid,veg, lowlands (veg soils are more cohesive making them harder to erode)
- Single deep channel
- Constant flow and high velocity
- Suspended load
- Finer Grained, moderate to well sorted (due to loss of grains because these are distal, sorting is proximal vs distal)
- Lateral Acreation surfaces (where you can see the fining process)
- Higher sand to mud ratio
- Deltas
- Stream velocity drops -> as does sediment (both bed and suspended)
- Progradation
- Characterized by modifier
- Delta Dominated by River (Mississippi, litterally pushed out into ocean)
- High wave action (barrier islands)
- High tidal ranges (pushed back in leaving elongated bars)
- Aluvial Fans
Drainage Networks
- Basins vs Devides
- Drainage Patterns
- Landforms -> stream Terraces, incised meanders, etc.
- Base Level Concept (surface to which erosion is working), below accululation, above erosion
Geologic Time
October 11, 2006
Hutton -> Lyell + Steno
Uniformitarianism
Laws -> methodological
Process -> methological
Rate -> substantive
State -> Substantive
Methodological is right, substantive is wrong
Geopetals -> fossils, riple marks, etc
Original Continuity -> strata which are now seperate were originally together
Fossile content allows us todo corrilation
If things crosscut, then they are younger than what they crosscut (duh)
Flow has a vasicular texture on top
a sill has a bake zone on both top and bottom
Index Fossils -> good skelletons
Disconformity -> both erotion and sedement can produce one
Sequance statigraphy (how to subdevide rock record)
Diachroneity -> same thing two different times
When a basen subsides it sinks
Lithostratigraphy (formal naming of rocks based on their lithological units)
Uranium -> Lead dating
Argon -> Argon dating
Argon doesn’t agree with Uranium
Some fossils are Diachronous
Chemostratigraphy -> use of chemical marker for dating
Planets
October 6, 2006
- Move with respect to background -> Word planet comes from greek for “wanderer”
- planets don’t twinkle
Aristotle (circa 350 BC) -> geocentric model of universe
The Moon
October 4, 2006
Visible phase determained by:
-
Current phase
- Position of the sun in the sky (time)
- Position of the moon in the sky
At sunset: full is rising, first quarter is high in the sky, new is setting (third quarter sets at noon)
Moon is offset from Earth Sun by .5*
Orbital plane of moon around earth is different than that of the earth around the sun
Only solar eclipse when phase is new
penumbra = outershadow of moon (only part of the solar eclipse)
umbral shadow = inner shadow of moon (full eclipse) about 300km on earth at a time and never longer than 7 minutes
annular eclipse (when moon doesn’t completely cover the solar disk), umbral shadow is not complete
Lunar eclipse is longer (earth is bigger)
- Takes hours
- Penubral shadow has almost no effect
- At totality, it looks red due to refraction through earth’s atmosphere
Sed Rocks -Con’t
October 4, 2006
It takes 2 moles to weather ignious rocks, but only 1 mole is returned by the calcium carbonate. So silcate weathering consumes CO2
Lithification process
- Compaction
- Dissolution
- Precipatation
- Recrystalization
- Cementation
Facies Concept
- Unique to where a rock forms
- Sediment transported to shore line
- sand facies is very high energy
- finer grain caries through sand to mud
- very little carries out to the carbonate faces
- Sand stone to mud stone to lime stone
- Facies can only be ontop or below ajacent facies
- The order in which they’re array’d gives us the sea level history (transgression or Regression)
- Durring regression erotion takes place
Major depositional environments
- Weathering and erosion (proximal) -> source rock and climate
- Transportation and sedimentation (updip to fluvial) -> distance, gradient, energy level (lakes vs river)
- Shoarline (dunes)
- Deltas
- Deep Marine
- rate of sink matters
Eluvial system
- Fan (not clay because not enough time) basement stuff (felpars)
- Braided (broad and wide streams)
Eolian depositis ->
- fine grained (weathered by wind)
- between proximal and distal
- Dunes migrate ontop of eachother
Meandering streams
- Big and deep
- flood eluvial vally
- deposits silt and clay
- going down: High energy to low energy
Delta
- Sudden energy drop
- While global sealevel is rising, the mississippi is regressing because of sedemens
- Opposite gradiant: find to course grain due to regression
Reaf system
- Limestones and dolastones (from magnesium from lagoons)
- Both high and low energy (high from ocean, low from lagoon)
Turbidites
- Clay -> courser then back to cley suddenly
- Graded bedding
- Energy of the flow highest when it gets to the site
- head of flow is course tail is finer.
Important stuff that didn’t fit anywhere else
- Lacustrine Deposits: Varves
- Layering caused by lakes
- Diagenisis -> everything not metamorphic
- Basement = Igneous rocks
- felspar becomes clay, but it takes time
Metamorphic rocks -> represent changes that occer in solid state (prior to melting)
- Recrystalization
- Phase changes
- Neo Crystalization
- Pressure solution ->the contact (touching point) is desolved between grains
- Deformation -> contact is not desolved
- Tend to find them in Precambrian sheilds and occationally folded mountain belts (due to their tectonic activity)
- Temp, pressure, fluids
Lithosphere goes down into mantal to stenosphere
Spectrum and Light
September 27, 2006
Hydrogen Atom
- Orbitals are quantized
- First level is ground state
- Each suceding orbit is higher energy
- The distance between orbits decreases the further you get out
- Spontaneous Emission -> when an electron makes a transition the electrion (atom) loses energy in the form of a photon
- Hydrogen Atoms have a peak at 1216A, the energy difference between first and second orbits
- Lyman series (transitions to or from first orbit)
- Balmer Series (transitions to or from higher orbits to or from 2nd) in optical spectrum
Measuring Velocity
- Dopler effect
- Tword you = blue shift
- away = red shift
- delta lambda / lambda = v /c
- Only measure Relitive velocity
- Only measures object moving along line of site
Telescope
Igneous Rocks
September 27, 2006
Processes
- Start off in the mantel and move out
- Two kinds: intrusive and extrusive
- Intrusive are under the crust and take long to cool (big crystals)
- Extrusive are volcanic and cool quickly (course)
- All part of the rock cycle
- Magma and lava – Controls
- we can do phase diagrams, except we flip the y-axis to represent depth
- Sources of heat
- Radiogenic decay (biggest)
- Impacts (meteorites)
- Gravitational Compression
- Sinking of Fe Alloys
- Tidal Frication
- To tell heat under the surface we find pressure gradiant and temp at surface and use adiabate to determain heat at depth
- We can cacluate preasure from gravitation
- Two melting curves for dry and wet (weather they contain volitiles) effecting how it melts
- Due to shape of curves decompression of rising magma causes it to melt
- For main causes of differentiation (the different make ups of igneous rocks from minerals)
- Differences in magma sources
- Partial melting (gaining bouyancy)
- Country rock (picking up shit on the way up), breaks off in xenoliths and melts, or melts on the sides
- Fractional crystalization
- Differentiation tends to be a comparison between high in Fe, Mg (mafic and ultramafic from the mantal from #1-2) to high Si, Al (felsyc from #3-4)
- Geotherm veries, average of 30*K per km (60*K in a basalt)
- Minerals – Bowen’s reaction series (melting points of minerals) -> olivine is high quartz is low, Plaglioclase is both
- Texture -> Rapid cooling is Fine-grained (aphanitic), slow cooling is Coarse grained (phaneritic)
- Porphyritic is a combination of aphanitic and phaneritic
- Distribution of igneous rocks
- Plate techtonic decide spreading of igneous rocks (mafic) through decompression cooling at divergant margins
- Subduction pulls under contental plates (fasyc) also known as a convergant margin
- Basaltic volcanism can happen in the contenants due to sufrace composition
- Caldera = colapsed volcano
- Snake river plane in Yellow stone demonstraits the movement of plate techtonics (the place of the volcano keeps moving)
Light
September 25, 2006
- Light is a form of electromagnatism
- Light has both Wave and Particle features (wave particle duality)
- Photon
- A Partical that carries the electromagnatic radiation
- Wave length: linear distance between two crests of the wave of a photon (lambda)
- Frequencey: Number of crests that pass over a unit of time (nu)
- A long wave length will have few crests over a unit of time
- Wave length and frequency are related by the speed of light: 3×10^5km/s or 3×10^10cm/s
- c = lambda * nu (where c is the speed of light)
- if lambda goes up then nu goes down (and vise versa)
- Visible light has very short wavelengths (on order of angstroms, 4000-7000)
- Hertz = one unit per second
- The energy of a photon = h*nu (where h is a constant)
- Spectrum
- Gamma (0 -> .1 A) Harmful, found in nuclear explosions, Very high frequency thus energy
- X-rays (.1 -> 100A) Harmful, but not in very small doses
- Ultraviolate (100 -> 4000A) Harmful with continued exposure
- Visible (4000-> 7000A) Small range from blue (4000) to red (7000)
- Infrared (7000A -> 1mm) Skin feels as heat
- Microwave (1mm-> 10cm) Like a microwave oven (which uses alot of microwave, like a bright light)
- Radio (10cm -> infinate) Need long wave length to get through water
- S
- Spectroscopy -> breaking up light into its components (like a prism)
- Using this we can plot the intensity of light as a function of wavelength
- Light can tell us about:
- Tempurature
- Movement
- Conditions
- Continuos spectrum (all wavelengths in a range)
- Stars often aproximate this
- Black body object (absorbs all light and reflect none, however does emit its own)
- Stars are blackbody because they emit light, but don’t reflect light (the moon does the exact opposite)
- The characteristics of a blackbody is that its tempurature is observable from its spectrum
- Plots (wv vs brightness) aproximates poisson distribution
- As the object cools, its “peak” moves from ultraviolet to infrared
- Higher tempurature emitis more radiation at all wave lengths
- Hotter may emit more blue than red (making it look cool) but it still emits more red than the cooler (red) one
- Wien’s law (lambda max * T = 2.9×10^7AK)
- Humans are 310k so lambda max = 100,000A, making us blackbody in the infrared spectrum (which is why the military likes infrared stuff)
- We’re visible in the visible spectrum because we reflect light
- Emited by solid, liquid or pressurized gas (star)
- Absorption line specturm
- If we put a cool cloud of gas between a star and ourselves we’ll notice certain wavelengths are missing
- Most stars have an atmosphere around them which causes them to apear as an absorption line spectrum
- Emission line spectrum
- Put the same gas agains the background of the universe we’ll see only certain lines
- These lines are the same lines which were absorbed when we looked at the sun through said gas
- These are due to electrons absorbing photons an jumping up into higher orbitals (thus ions absorb and emit differently than once with full valiance shells)
- 90% of the universe is made of H, so we talk about that alot