Geology Final Exam

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What are the three rock types and how do they form?: 1) Igneous Rocks develope when hot molten rock cools and freezes solid.
2) Sedimentary Rocks form from grains that break off preexisting rock and become centered together, or from minerals that precipitate out of a water sollution; an accumulation of loose mineral grains is called a sediment.
3) Metamorphic Rocks are created when preexisting rocks undergo changes including the growth of new minerals in response to heat and pressure
What is the Theory of Contitental Drift?: Suggested that a vast super continent called Pangaea existed in the age of the dinasours. When it broke apart it then drifted away from each other. Concluded that the maps of the 1500 showed fits among continents which were to good to be coincidence. Wegener determined that the distribution glacations at the end of the paleozoic era could easily be explained if the souther part of the pangae located over the south pole, but not if the continents were in there current locations.
*Tropical Plant fossils in Norway and Greenland
*Ancient Dessert Deposits in Anartica
Describe the Theory of Sea Floor Spreading.: Hess suggested that that molten rock rose upward beneath mid ocean ridges and taht this material solidified to create oceanic crust. The new sea floor then moved away from the ridge.
*Cools down and sinks
*Cosumed at ridges
What is a Palepole?: The proposed position of the Earth's Magnetic pole in the past, with respect to a particular continent.
What is a Polar Wondering Path?: The curving line representing the apparent progressive change in the position of the Earth's Magnetic pole; relative to the locality of X, assuming that the position of X on Earth has been fixed thorugh time( in fact poles stay fixed while continents move)
What is a Polar Wander?: The phenomenon of the progressive changing through time of the position of the Earth's magnetic poles relative to a location on a contitent; significant polar wander probably doesn't occur-poles remain relativly fixed.
What is Magnetic Polarity?: When Examining the Sea Floor geoligist found that alternating layers of rock had the same polarity as the Earth's current magnetic field and others (rement) had opposite, called Magnetic reversals.
What was the discovering of the Asthenosphere?: The Lithosphere floats on a relatively soft layer called the asthenosphere composed of mantle that can flow very slowly because it is hotter than lithosphere rock by 260 degrees celcius.
What is the lithosphere?: A group of 20 plates which move relative to each other.
The lithosphere consists of the crust plus the top cooler part of the mantle. It behaves rigidly, does not flow easily.
What are the types of Plate Margins?: Divergent=Ridge
Convergent=Subduction Zone
Transform=San Andreas
What is a diverging plate boundar y?: 1) Divergent Boundaries/Extension
Widespread magnitism, small scale earth quakes. Rifting.
Here two plates move apart by the process of sea floor spreading. These boundaries are marked by a mid ocean ridge. Asthenospheric mantle rises beneath a mid-ocean ridge and partially melts forming magma. The lithospheric mantle thickens progressively away from teh ridge axis as the plate cools
Converging plate boundary?: 2)Convergent boundaries
*Compression
*Subduction (Trenches)
*Magnetism(Volcanic Arc)
*Mountain Building
*Large Earthquakes
Types
Oceanic-Oceanic
Oceanic Continental
Continental Collision
Here to plates move together or converge and one plate sinks below and under the other. Only lithosphere can subduct. At the earths surface the boundary is marked by a deep ocean trench. forms a volcanic arc.
Transform Boundary?: *Shear
*No rifting
*no mountain building
*no magnetism
*large eq's
What is a mineral?: *Homogenous
*Naturally Occuring
*Solid
*Inorganic
*Definable Chemical Composition
*Orderly Arrangement of atoms in a
latice
*Definite Internal Structure/physical properties
Fully describe the Rock Cycle, including all the possible "short cuts": At the begginning of the rock cycle atoms from the mantle rise in a matle plume. It melts at the base of the lithosphere then become part of the basaltic mantle and rises through the lithosphere and erupts in a volcano.
The atoms become part of lava flow, that is igneous rock. Weathering breaks the lava down and the resulting clay is transported to a passive margin basin. After the clay is burried the atoms become part of shale, a sedimentary rock. When sea floor spreading takes place teh rock is futher burried beneath the resulting mountain range. The atoms become part of schist a metamorphic rock. Rifting causes igeneous activity to occur again.
What is an Atom: The smallest piece of an element
consists of a nucleus surrounded by a cloud of orbitting electrons, the nucleus is made up of protons and electrons(except in hydrogen) Electrons have negative charege, protons positive, neutrons neutral charge.
What is atomic number: The approximate number of protons in an atom of an element
What is an Ion: An atom that is not neutral.A anion is an ion with an excessive negative charge. An excessive positivly charged ion is calle a cation.
What is an Igneous Rock?: Form from cooling and freezing (solidification) of molten rock or melt.
What is an intrusive igneous rock?: A rock made by freezing of magma underground, after it has pushed its way into preexisting rock of the crust.
Extrusive igneous rock: Rock that forms by the freezing of lava above ground after it spills out or extrudes onto the surface of the earth, and comes in contact with the atmosphere or ocean.
What is Magma Made of?: Most magmas contain silicon and oxygen which bond together. Si 50-70%
the rest is: Aluminum, Calcium, Sodium, Potassium, Iron,
What happens to the elements Fe, Mg, Ca, Na, and k with increasing Si?: The go down,
the elements sodium and potassim increase
What is the chemical composition of Mafic Magmas?: Rich in Magnesium (mg) and Iron (fe)
What is the chemical Composition of Felsic Magmas or Silic: Rich in Si little Mg or Fe
The composition of Minerals is controlled by the composition of what?: Magmas
Mafic Minerals are what color?: Dark
Felsic Minerals are what color?: Light
Slow cooling creats what type of rock?: Phaneritic
Fast cooling creates what type of rock?: aphantic
Very fast cooling creates what type of rock?: Crystal or glassy rock
Slow & Fast cooling creates what type of Rock?: Porphorytic
What are the enviromental Controls of Cooling rates?: Below the surface slow, phaneritic
Above the surface fast, aphaneritic or glassy

Below then Above the surface
Porphorytic
slow then fast
What are the types of textures for the rates of cooling?: Slow=course grained
Fast=Fine Grained
What is Bowen's Reaction Series?: Bowen Found that different silicate minerals crystalized in a specific mafic melt do so in a specific sequence.
Olivine and Calcium Rich Plagioclase came first. Then pyroxene, amphibole, biotite cyrsallize, quartz, K-Feldspar, muscovite.

Discontinous reaction series includes oliveine pyroxene amphibole,biotite, K-feldspar/muscoviet quartz.
Continous yields Plagioglass.
What is the difference between Chemical and Mechanical Weathering?: Mechanical is the physical weathering at the earts surface, wheras chemical is the chemical weathering
Chemical weathering is the chemical reaction in which minerals are altered or destroyed when rock comes into contact with air or water sollutions.
Physical weathing is the proccses of intact rocks breaks into smaller grains.
What are the proccess in which Mechanical weathering can occur?: *Glacial Action
*Freeze Thaw(temp cycles above&below freezing point of water)
*Biological (Tree roots)
What are the procceses by which chemical weathering occurs?: Places minerals in a chemically unstable enviroment, from which they are used to, chemical reactions occur to produce stable and "new" minerals.
What are the types of Chemical Weathering reactions?: 1)Disolution
Complete dissolution of mineral in water, produces aions and cations
2)Hydrolysis
Acid water=produces clay
3)Oxidation
What controls the chemical weathering rate?: 1)temperature
2)acid
3)water
4)mineral content
High temperature Minterals at the earths surface are more unhappy and will weather faster, first on bowens reaction series.
Where is chemical weathering most efficient?: Hot wet warm vegetation rich
Less efficient in cold dry non vegetation regions
What is the formation of Sedimentary Rocks?: Weathering
Erosion (loosens seperates
Transportation
Deposition(when the medium can no longer carry the sediement.)
Lithification
Compaction (squeezes out water clast tightly together
Cementation sediement bound together after compaction.
Where do biomechanical sedimentary rocks come from?: shells and shell debris
Where do chemical sedimentary rocks come from?: Rock formed by the precipitation of minerals out of water sollutions at the surface of the earth.
What are Evaporites?: Salt deposites form from the product of evaporation
What is sorting?: Measure of the variation of particle size.
The range of clast sizes in a collection of sediment
the degree to which sediment has been seperated by flowing currents into different size fractions
What is compaction?: A type of litiphication in which sediment bonds together.
most common in very fine grain (mud)
Increases contact surface area
What is cementation?: ground water with disolved stuff
new minerals
increases contact surface area
med. grain size most common
What are the 3 fundamental groups in which sedimentary rocks are classified?: 1)Clastic or Detrital broken down rocks
litified clastic sediment.
inclues
mud, silt, sand, boulder,pebble, cobble
Splits easily into two sheets
Shale
Sandstone
Conglomerate

2) Chemical Direct precipitation from water
evaporation of h20
Limestone
Evaporite
Chert

3)bio chemical
Biochemical sedimentary rocks are mud up shells of organisms
secreted by organims
organisms converta aions and cations into hard parts
What is the difference between lithostatic differential pressure?: Lithostatic is pressure from all directions like a person in a swimming pool. Differential is directed pressure not uniform in all directions
What are the agents of Metamorphism?: Heat Pressure and fluids
What are the types of Metamorphism?: Contact-Heat due to intrusion of hot magma into cooler rock, no change in pressure, increase in temperature no fluids
Regional-Heat and pressure usually associated with plate convergence and mountain building, continental-continental collision
Metasomatic- Heat and fluids. Due to intrution of hot and wet magma into cooler dry rock.
Contact+fluids
increase in temperature
What are the 3 aspects of Metamorphisim: 1)Increase in Crystal/grain Size
2)Change in Mineral Content
3)Change in Texture texure, foliation
What is the Classification of Metamorphic Rocks?: Foliated
Non Foliated
What is the definition of an Elastic Solid?: Bends when Stress is applied
returns to its original shape when stress is removed
What is a plastic Solid?: Bends when stress is applied
DOES NOT return to its original shape
What is elastic Limit?: Point at which an elastic Solid Ruptures, returns to its original shape, releases energy
What are the body waves?: P and S waves
They travel through the earths interior
What is a p-wave: Primary waves are compressional
push and pull the rock
travels through liquids and solids
fastest body waves
What is a s-wave: secondary wave
move perpendicular to the direction of which the wave itself moves travel %60 the speed of p-waves
Travel at right angles
travels through solids not liquids
What are surface waves?: R and L waves
combined up and down; side to side motion
most earthquake damage is due to these waves
slower than s-waves
What is the anatomy of a stream?: Source,Gradient, Baselevel(local,ultimate) Mouth
What is the source of a stream?: Where the stream begins;initial collection point
What is the mouth?: Where an outlet is, or stream discharges its contents into another
What is the Gradient of a stream?: the slope of a stream steep, shallow
slope is greater near the source
lower near the mouth
What is the base-level of a stream?: Local- a lake
Ulitmate-Ocean
What is a Valley?: Region Occupied by the stream over a long period of time
What is the Channel: Region occupied by the stream at any given time
What is Stream Discharge?: The amount of water that passes by a point over a certain interval of time
increases closer to the mouth
*equal to cross section area of stream x stream velocity
What is stream load?: The total amount of sediment carried by the stream as sediment load.
What is stream capacity?: The total quantity of setiment it can carry
What are the characteristics of streams above base level?: *Abudant Erosion
*High Gradient
*No deposition
*Small discharge (load=capacity)
*High Velocity
*High sediment load
What are the characteristics of a stream near baselevel?: *Low gradient

*High Discharge
*Erosion is lateral
*result is floodplain
*transportation is minimal
*meandering
What are the characterisics of a stream at base level?: Gradient=zero
Velocity goes to zero
All transported material is deposited

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