Catastrophic Events Flashcards
Scientific method:
Observation, hypothesis, testing, theory, testing, law
Father of stratigraphy
Nicholas Steno
Uniformitarianism concept:
Understanding history of earth’s surface based on current processes (weathering, sediment transport by water/wind, production of layered sediments in lakes)
Recognized marine origins of fossils:
Nicholas Steno
Assumed all uneven features of Earth were caused by Noah’s flood:
Thomas Burnet
Determined that the beginning of earth was Oct 22 4004BC based on Biblical research:
Archbishop Ussher
Studied the sedimentary rocks forming the laters of the Paris Basin and interpreted findings as evidence of reported states of sudden flooding:
Baron Georges Curvier
Calculated earth’s history to be ~6000 years old based on work with sedimentary rocks:
Baron Georges Curvier
Catastrophists believe:
mountains, valleys, fossils, species
Earth began as molten ball; as it cooled it went through a series of intermittent global convulsions that threw rocks into mountain formations
Valleys were erosion from Noah’s flood
Fossils represented previous life forms that were killed off during catastrophic events
All species are independent.
The first person to RECOGNIZE the concept of uniformitarianism (gradualism):
Leonardo da Vinci
Father of modern geology:
James Hutton
First person to formulate and name the concept of gradualism:
James Hutton
Who was a deist?
James Hutton
What does it mean to be a deist?
Believe in a deity but not in divine intervention or the conformity of natural processes to scriptures
Why did James Hutton think that the earth was older than the Bible said?
Knew that it took a very long time for weathering, erosion, transportation, deposition elsewhere and solidification into rock
Who created the law of uniformitarianism:
Charles Lyell
Who championed Hutton’s views of uniformitarianism:
Charles Lyell
Law of Uniformitariansm:
the present is the key to the past
Age of earth:
4.54 billion years old
Who created the principle of superposition:
Nicholas Steno
Principle of superposition:
in any vertical sequence the oldest layers will occur the base and the youngest layers will be at the top
Who created the principle of original horizontality:
Nicholas Steno
Principle of original horizontality:
sedimentary strata would have lain flat when they were first deposited
Who created the principle of original lateral continuity:
Nicholas Steno
Principle of lateral continuity:
the flat lying sedimentary strata would have initially been extended in all directions
Who created the principle of cross cutting relationship:
James Hutton
Principle of cross cutting relationship:
the fault is younger than the rock it cuts
Angular unconformity:
the contact that serapes a younger, gently dipping rock from older underlying rocks that are tilted or deformed rock
Disconformity:
erosional contacts that are parallel to the bedding planes of the upper and lower rocks
Non-conformity:
the contact that serapes a younger sedimentary unit from an igneous intrusive rock or metamorphic rock
Who created the principle of faunal succession?
William Smith
Why did William Smith create the principle of faunal succession:
noticed that the individual layers in sedimentary strata he was working with each contained characteristic fossils that were distinct to those in the layers above and below
Principle of faunal succession:
the same layer in different parts of the country; based upon fossils - able to build composite stratigraphic column
Present era:
Cenozoic era
What era did dinosaurs go extinct?
Cenozoic era
What era did Pangaea break up?
Mesozoic
Who discovered radioactivity?
Henri Bequerel
Isotope:
atoms of the same element that differ in number of neutrons
What are the 3 ways isotopes decay?
proton will turn into a neutron (vice versa)
2 neutrons + 2 protons (=alpha particle) ejected from nucleus
mission of stray neutron hits a large nucleus and causes instability breaking in two
How many half lives occur before the amount of parent remaining in rock is too small to measure?
10
When to use carbon-14 dating?
In last 50 000 years
Layers of earth:
inner core, outer core, mesosphere, asthenosphere, lithosphere, hydrosphere, atmosphere
Composition and % of inner core:
solid, hot, nearly pure metal; 20%
Composition and % of outer core:
liquid, hot, nearly pure metal; 35%
Composition and % of mesosphere:
stiff plastic, very dense rock behaving like solid; 40%
Composition and % of asthenosphere:
soft plastic, liquid in some spots; 4%
Composition and % of lithosphere:
soild, cold, brittle; 1%
Radius of earth:
6371 km
What layer of earth was once known as ‘mantle’?
mesophere and asthenosphere
What layer of earth was once known as ‘crust’?
lithosphere
Differentiation:
heavy material moving towards the planets core forming layers of earth.
Internal energy of earth comes from:
radioactivity
Who formulated the theory of continental drift:
Alfred Wagner
Who first noticed ‘spreading centers’?
Henry Hess
Paleomagnetism:
the study of earth’s magnetic field through the analysis of rock magnetism
Dynamo model:
electric currents are generated by enormous dynamos driven by circulating hot currents in the liquid metal outer core, and magnetic fields surround those electric currents
inner core is rotating at faster than the rest of the planet.
Magnetite crystals form in what rock?
Basalt
Where will magnetite crystals point exactly vertical?
North/south poles
Where will magnetite crystals point exactly horizontal?
Equator
What did Vine and Matthews discover?
Magnetite crustals in the basalt were oriented according to the magnetic north/south; found a pattern of alternating strips of orientation was age related
Volcanic ridges mark…
spreading centres; subduction of 2 continents
Focus:
point where failure starts
Epicenter:
point on surface exactly vertically above focus
Characteristics of P wave:
fast, compressional wave; dependent on density; travel through anything
Characteristics of S wave:
slower; travel through solids
Body waves =
P wave + S wave
Surface wave characteristics:
destructive; slow
Types of surface waves:
love wave, rayleigh waves
Characteristics of love wave:
move forward across surface - side to side oscillation
Characteristics of rayleigh wave:
move forward across surface - up and down backward rotation oscillation
Who first developed the seismograph?
Hugo Benioff
What did Hugo Benioff find with his seismograph on the ocean floor?
Earthquakes along trench surface sloping downward and away from ocean side ward the continental plate side
Who perfected the seismograph?
Charles Richter
Divergent boundaries mark…
Spreading centres
Spreading centres mark…
Divergent boundaries
Convergent boundaries mark…
Subduction zones
Subduction zones mark…
Convergent boundaries
Transform boundaries mark…
Strike slip faults
Strike slip faults mark…
transform boundaries
Proof of Hawaii chain formation theory:
Volcanic islands not of Hawaii are dead
Increased volcanic activity south of Hawaii
New sea mount forming on south coast
Hot spot entered beneath the big island (new new volcanic mound)
Where do mantle plumes originate:
core-mantle boundary
What earthquake scale was used before Richter scale?
Modified mercalli intensity scale
M1 =
Richter magnitude scale
The “standard” earthquake:
One hundred km from the source; 1 mm amplitude; magnitude 3
The 10x factor for earthquake magnitudes holds true until…
7
MW =
Moment Magnitude Scale
Total energy is calculated from _, _, _ to form MW reading:
Total measured area
Amount of offset
Strength of rocks
Paleoseismology:
Study of ancient earthquakes by reading the rock record
Liquefaction:
Intense shaking can cause water-saturated sediment to change rapidly form a solid to liquid
Earthquake characteristics at divergent boundaries:
Numerous, low magnitude; normal fault
Earthquake characteristics at convergent boundaries:
Largest earthquakes
Earthquake characteristics at transform boundaries:
Shallow; only bad on continents
Needed for earthquake prediction:
Location
Time
Magnitude
Foreshocks:
microfractures in weaker rocks
Seismic gap:
no motion on a section of the fault although motion does occur frequently on other sections of the fault boundary
Indications of fracturing:
Drop in P wave speed and electrical conductance; radon gas; drop in water levels
Earthquake capitol of the world:
Parkfield, California, US
Most devastating tsunami?
Sundra megathrust earthquake (Indian ocean)
Shoaling effect:
tsunami get higher as the water is shallower
Tide retreats before tsunami:
draw down
PTWC monitors earthquakes above…
6.5
Transform earthquakes occur in:
San Francisco
Biggest/worst earthquake occured in:
New Madrid, Missori; intraplate fault
Concept of transform faults by:
Turzo Wilson
On land, transform faults appear to connect…
convergent and/or divergent plate boundaries
Plutonic rocks:
Magma solidified below surface
Igneous rock:
All types of rock produced from magma (volcanic or plutonic)
The amount of exsolved water increases when..
Temperature decreases
Types of basalt:
aa basalt
pahoehoe basalt
Characteristics of aa basalt:
rubbly looking rock; les water
Characteristics of pahoehoe basalt:
smooth-surfaced, ropey looking rock; more water
Three types of magma (increasing order of modification):
Basalt, andesite, rhyolite
As magma modification increases, SIO2 content…
Increases
As magma modification increases, temperature…
decreases
As magma modification increases, viscosity…
Increases
As magma modification increases, dissolved water content…
Increases
As magma modification increases, explosiveness…
Increases
Basalt is more _ rich:
Ca
Andesite is more _ rich:
Na, Si, volatile
Rhyolite is more _ rich:
K, Si, volatile
Asthenosphere rock will melt by:
Increasing temperature, decreasing pressure
Magma produced at ocean spreading centres =
MORB: mid ocean ridge basalt
Type of rock that melts (asthosphere) in ocean spreading centres =
Peridotite
Assimilation:
Hot magma works its way into fractures of surrounding rock; loosens blocks of rock with gradually fall into the magma which melts
Fractional crystallization:
At cooler temperatures crystals begin to form in the melt; if they are crystals of minerals that are relatively heavier than the melt they will fall through the magma towards the base and may form a rock
Magma mixing:
two magma chambers join together
Nuee ardent:
pyroclastic flow that is red hot
3 main volatiles in magma:
water, CO2, SO2
Pyroclastic products:
fragmented rock, magma, ash
Lahar:
mudflow of pyroclastic material + water + anything else; turns to solid
Periods between volcanic eruptions:
repose
Short period earthquakes in volcanoes indicate that…
Magma chamber is fracturing
Long period earthquakes in volcanoes indicate that…
Magma has left the chamber and is ring toward the surface (imminent eruption)
Good eruption precursors:
tilt meters
CO2:SO2 ratio (high)
high frequency of earthquakes
Plinian eruptions:
vertical eruptions
Pelean eruptions:
horizontal eruptions
The eruption is only exposive if (3):
High visocity (high Si) High content of exsolved volatiles Cap of volcano suddenly ruptures
Volcano of ‘atlantis’:
Akrotiri of Santorini
Mount St Helens and Mt. Versuvius lie on a…
Subduction zone
History of Hawaii volcanoes:
~75 mya first island gradually build up from sea floor
Pacific plate drifed over mantle plume forming string of islands
~43 mya direction of shift changed
Magma erupting in Hawaii is called
alkali basalt
When mantle plumes/hotspots form under ocean plates they will…
Initiate spreading centre
Form Hawaii-like islands
When mangle plumes/hotspots form under continents they will…
form giant resurgent calderas
What is the cause of 2 species mass extinctions?
Flood basalts
Flood basalts form on top of …
Large igneous provinces
The only continental basalt plateaus that do not appear to be related to continental splitting are the…
Columbia river basalt and the siberian basalt
Techniques for radioactive dating rocks:
K Ar
40Ar - 39 Ar (more reliable)
Event for causing species extinction 251mya:
Siberian traps
Event for causing species extinction 65 mya:
Deccan basalts
